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Warm Mix Asphalt - Aapaq.org

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3E® warm mix: a cooLer way to protect the environmentWith manufacturing and application temperatures that are 40°C to 45 °C lower than conventional hot mixes,3E® Environmentally-friendly, Energy Efficient warm mixes help ensure energy savings and greenhouse gas reductionsof 15% to 25%. When 3E® is combined with a recycling technique to make 3E®+R, up to 50% reclaimed asphaltpavement [RAP] can be used. 3E® and 3E®+R mixes are designed to provide environmentally-friendly road surfacing,at the heart of the French Grenelle Environnement roundtable agreements. Their environmental performance pavesthe way for responsible roads.rhe road forward


Jean-louis MarchandPublication Manager• europeanroadsre v iewRevue generale des routeset des aerodromes SAS, editeur132 rue de Rivoli, 75001 ParisTel. 01 4073 SO 00 - Fax 01 49 52 01 SOTo subscribe4 ERR (Europeanroads review)125 € France, Switzerland, EU135 € other countries35 € per copyHonorary PresidentsFran~ois Bonis CharancleYves GhironPublication ManagerPresidentJean-Louis Marchandjlmarchand@editions-rgra.comManaging EditorMarie-Fran~oise Ossolamfossola@editions-rgra.comMaquetteRed LineTel. 0141 1401 SOAdvertisingEmmanuelle Hammaouiehammaoui@editions-rgra.comCommission paritaire n° 0111TS025SImprimerie Chi rat744, rue de Sainte-Colombe42540 Saint-Just-Ia-PendueTel. 04 77 63 25 44 - Fax 04 77 63 50 13Les articles figurant au sommaire de la RevueGenerale des routes sont publies sous I'entiereresponsabilite de leurs auteurs. Tousdroits de reproduction, adaptation, totale oupartielle, France ou etranger, sous quelqueforme que ce soi, sont expressement reserves(Copyright by RGRA). Ouvrage protege ;photocopie interdite, meme partielle (loi du11 mars 1957), qui constituerait contrefa~on(Code penal, article 425).Depot legal . Spring 2011 • W 201106.0325ISSN 1763-30S7In order to receive future editions, I inviteyou to fill the inserted subscription formand send it back to us as soon as possible;in this way you will not be deprivedof the information you are lookingand that ERR provides you with.Please email your requestat the following address:rgra@editions~rgra.(omgoPaving of a highway sectionin France using warmmix asphalts producedwith chemical additivesIIlnnovation and willingnessto change are needed llThis issue of europeanroads review focuses on the subject of warm mixes.Reviewing the past ten years and how warm mix technologyhas gradually developed is very interesting because it showshow difficult it is to change, and how simple it is to innovate,when you are willing to change the way you think (or the wayyou have always thought) .Still ten years ago mixes needed to be as hot as possible for a lot of reasons(delivery distance, handling ease, etc.); everything had to be done to avoidor eliminate water during production; energy was cheap, nobody spokeabout (0 2 , those were the old good days; it was the past century.Whoever was first to think of adding water in the production process to reducethe required temperature is unknown or may be controversial.But he (or she) opened a way that will have a very strong influencein the paving business throughout our century!The goals that have been ach ieved in the USA in 2010 (about 36 million tonsof warm mixes produced in the year!), the various techniques usedfor producing several types of mixes, reaching different levelsof temperature between 900( to 135°(, offering a range of solutionsfor clients depending on their needs and the price they are ready to pay,are exceptional. All of which is the result of joint efforts between asphaltproducers, manufacturers of equipment, paving companies, workersrepresentatives, laboratories and Public Administrations, working towardsreduced exposure to bitumen fumes, which only appears above 135°C.The europeanroads review is dedicated primarily to the exchangeof experiences or best practices in road construction between Europeancountries; but comparison with North American developments is alsovery useful, especially when it challenges us by asking why there is such a gapbetween the use of warm mixes in the USA and their use in Europewhich is generally estimated to be at a very" modest" level.Everyone sees and feels that things are changing worldwide very quickly.Mobility and infrastructure are increasingly needed, but the environmentalissues, the public expectations and the lack of money bring us in a pointwhere we have to rethink how we are used to working . Innovationand willingness to change are needed. The development of warm mixesin Europe will be a good indicator of our capability to meet the challengeswe are facing.


ED I TORIAL"Innovation and willingness to change are needed"Jean·louis MarchandWarm Mix AsphaltWarm Mix Asphalt in the U.S.In 2000. The National Asphalt Pavement Association (NAPA) became awareof efforts by contractors in Europe to reduce the production and placementtemperatures of asphalt mixtures. This was an intriguing developmentto the hot mix asphalt industry in the U.S. because of the inherent potentialfor environmental and operational advantages.David Newcomb"Achieving densityconsistently with more flexibilityis one of WMA'S advantages"74Development of a new Warm Mix Technologyoffering enhanced Asphalt Properties 21Today, environmental and safety concem~ not only economic factors are drivingnew developments in the road construction industry. One of these developmentsis warm mix - manufacturing and paving bituminous mixtures at lower temperatures.Akzo Nobel has introduced a new approach to warm mix and this article detailsthe research and testing carried out in independent and governmental laboratoriesand road trials in USA and Europe with the chemical additive Rediset WMX.Sundaram logaraj, Mark Smith, Alan James, Mats NorellSasobi~ wax additiveused in this study to producethe WMA mixtures))...JInterstates 55 and 57 in Missouri170,000 tons of Warm Mix 7170,000 of Foamed Aspha lt Mixes were placed between June 2009and October 2010 in the base and the shoulders of the I-55 11·57 Projectin southeastern Missouri; making it the largest Warm Mix road projectever completed to date.In addition to contract technical obligations, a thorough Performance,Constructabi lity and Environmental evaluation was completedby Colas' operations. eq uipment and laboratory person nel.Foamed Asphalt Mix production met all volumetric and density requirements.Jean·Paul Fort, Glen Graham, Shannon SinnWarm Mix Asphalts (WMAs) with chemical additives 14Warm mix asphalts (WMAs) are produced, laid and compactedat lower temperatures than those usually required for hot mix asphalts (HMAs).Several WMA techniques, based on different physical processesand additives, are already available on the market.Here it is described one specific technique, based on a chemical additive,to produce WMA (Ceca base RT~) . The use of this chemical additiveallows the reduction of about 40°C of the standard hot mix asphaltproduction temperature.Juan A. Gonzalez le6n, Sandrine ligier, lionel Grampr,e, Gilles BarretoAn evaluation of unusual Warm Mix Asphaltsproduced with wax additives 26There are several technologies to produce Warm Mix Asphalts (WMAs),namely by using water. surfactants, and organic or wax additives to affectthe temperature reduction. A particular wax additive (Sasobi~)was studied in this work. which reduces the viscosity of the binder above 100°C,while notably increases the stiffness at operating temperatures.Hugo M.R.D. Silva, Joel R.M. OliveiraTransport StrategiesThe European Commission White Paperon the Future of TransportThe point of view of the European UnionRoad Federation (ERF) 34On March 28, 2011 , the European Commission (EC) released its White Paperon Transport, establishing the future framework of the transport strategiesfor Europe in the future.In the principles the EC White Paper recognises the importance of mobilityand transport for the European economy and society.Christophe NicodemeADVERTISERS INDEXAIPCRBP33OBCCOLASEURASPHAlT & EUROBITUMEIFCIBCEUROPEAN UNION ROAD FEDERATIONERR' Subscription form page 7541


europeanroadsrev i e wSustainable DevelopmentValorcol: asphalt mix complying with environmentand sustainable development 56Depletion of natural resources and climate change are among the chiefcauses of the degradation and disruption of our ecosystems.The main culprits are: industries, agriculture, transport.Although not on this list, road construction companieshave already been demonstrating for several years their awarenessand concern regarding the preservation of our environmentand our natural resources.Jean-louis CuenoudPreventive maintenanceInnovation for Long-Life PavementsRegional Asset Management Effortsand a Performance-based Approach to Local Streetsand Roads Funding AllocationOften when allocating funds to local agencies for street maintenanceand rehabilitation, a metropolitan planning agency (MPO) will employa "fix-the-worst-street-first " approach or will allocate funds based solelyon which agency has the worst roads and thereby the greatest financial need.Theresa Romell, Sui G Tan37GB5®: Eco-Friendly Alternative to EME2for Long-Life & Cost-Effective Base CoursesAggregate packing concepts developed in the field of high-performancecement concretes, initially by A. Caquot (1937) then by contemporaryresearchers since the 1970's, were transposed to the fieldof asphalt concretes (ACs).Fran~ois Olard, Patrick Huon, Stephane Dupriet61Bitumen Emulsion ProductionBitumen Emulsion in 2010: a watershed yearThe International Bitumen Emulsion Federation (IBEF) is the unionof national associations representing the bitumen emulsion industryof 19 countries and more than 70% of world production.last October during its 5th congress, held along with the World of Emulsions(WOE 2010), some 250 delegates from 30 countries were brought together.Etienne Ie Bouteiller, Jean-Claude Roffe42Rugosoft Holbaek projectAirfield pavement regulationThe Airbus high tire pressure test (HTPT) 50When the International Civil Aviation Organisation (ICAO)initiated the Aircraft Classification Number/Pavement Classification Number(ACN/PCN) system in 1978, they included a simplified means for airports to categorizetheir pavement as either rigid (Portland cement concrete) or flexible(bituminous asphalt) pavement, an index of subgrade (natural soil) categoriesthat expresses the bearing strength of the soil on which the pavement rests,and an allowable tire pressure.Cyril Fabre, Jean-Maurice Balay, Dominique GuedonTrafic noise reductionNoise-reducing asphalt mixes: The Danish ExperienceThe roll-out phase of new special products always involvestrial sections on which performance levels are monitored over time.However, these sections are rarely analyzed in the medium-term.lars ladehoff, Xavier Carbonneau69


David NEWCOMBP.E., Ph.D.National AsphaltPavement Association (NAPA)(USA)- ---l Warm Mix AsphaltWarm Mix Asphalt in the u.s."Achieving density consistently with more flexibility is one of WMA'S advantages"JIn 2000, The National Asphalt Pavement Association(NAPA) became aware of efforts by contractorsin Europe to reduce the production and placementtemperatures of asphalt mixtures. This was anintriguing development to the hot mix asphaltindustry in the U.S. because of the inherent potentialfor environmental and operational advantages.NAPA then undertook a scanning tour of Europefor U.S. asphalt mix producers in 2002. The informationthey brought back began a virtual firestormof activity to investigate warm mix asphalt(WMA) technologies and their application in theU.S. market.How to manufacture WMAs ?In 2004, research into warm mix beganat the National Center for Asphalt Technologyat Auburn University, and the first U.S. field trialwas constructed at the World of Asphalttrade show in Nashville, Tennessee using a zeolitetechnology from Europe. The Federal HighwayAdministration (FHWA) and NAPA joined forcesto monitor the development of warm mix asphalt(WMA) and provide guidance on its use in 2005through the formation of the Warm Mix AsphaltTechnical Working Group (TWG).As more contractors and states beganto experiment with this new approach to asphaltmix production, more technologies for loweringtemperatures began to be developed.Currently, there are about 30 different processesand products to manufacture WMA in the U.S.These are roughly divided into three categories:• Chemical additives,• Plant foaming devices,• Material foaming processes.Chemical additivesChemical additives can be divided intotwo classes: organic (long-chain waxes)and surfactants.Long-chain waxes work by lowering the viscosityof the binder at working temperaturesand then hardening at service temperatures.Some of these materials have long been employedas compaction aids for hot mix asphalt (HMA),but are also effective at lower temperaturesallowing an energy savings in production.Surfactants act to lower the surface tensionof the liquid binder, improving its ability to coatand compact at lower temperatures.Production and placement temperaturesmay be lowered by as much as 30 to 40°C.Although they generally do not require capitalinvestments, the unit material costs are increasedwhen using chemical additives.Plant foaming devicesPlant foaming devices are systemsthat can be mounted on batch plantsand continuous plants that inject a small amountof water (1 to 3% by weight of bitumen)to the liquid before it is introducedto the aggregate. As the water comes into contactwith the hot bitumen in an expansion chamber,it vaporizes and expands to about 1,700 timesits liquid volume causing the binder to expandby five to ten percent. This increase in volumereduces the mass viscosity of the liquid binderand allows more thorough coatingEll eu "opeanroads review 1 B • Spring 2011 • RGRA


of the aggregate particles. Production temperaturesfor mechanical foaming systems range from 121°Cto 135°C, although contractors have foundbenefits to using foaming systemseven at higher temperatures. The financial benefitto plant foaming systems is that they area one-time capital cost to the plant owner.Material foaming processesMaterial foaming processes use either moist sandor zeolite (a water-bearing mineral) to foamthe bitumen as it is being mixed.These use the same principle of volume expansionthat plant foaming systems use.In one case, hot asphalt and coarse aggregateare combined and then the sand fractioncontaining a carefully controlled amountof moisture is added causing the expansionof the binder. A coating additive is also employedin the wet sand method. In the case of zeolite,the mineral itself contains a small amountof water in its crystalline structure that is releasedat high temperatures. For these technologies,temperature reductions are on the orderof 30 to 45°(,The wet sand method requires plant modificationsas well as the use of an additive.The zeolite requires modification of the plantto introduce the material as well as the costof the zeol ite.WMA's advantagesWhile all these approaches have some sort of costassociated with them, contractors and agencieshave both found a number of advantages in usingthem . These were identified [1] and they are:1. Compaction Aid,2. Cold-weather Paving,3. Longer Haul Distances,4. Use of Higher Percentages of Reclaimed AsphaltPavement (RAP),5. More Paving in Non-attainment (Air Pollution)Areas,6. Specific Plant Concerns,7. Specific Pavement Rehabilitations,8. Reduced Fuel Usage,9. Reduced Emissions,10. Improved Working Conditions.WMP:s workabilityThe first three issues are interrelatedand they are the result of the improved workabilityof the asphalt mix at lower temperatures.Contractors are reporting that they havean easier time achieving density with warm mixthan regular hot mix, and that they are able toachieve a more consistent density. Consistent densityis very important when statistically basedconstruction specifications are usedbecause the contractor is not only paidon the mean density but also the variability.Because the mix does not cool off as rapidly,the mix can be placed at colder temperaturesor transported over a longer distancebefore it is placed. In some cases, haul distancesof 96km have been reported with no problemsin placement or compaction. The ability to beflexible in selecting working conditionsor site locations provides contractorswith a competitive advantage.RAP's incorporationBeing able to incorporate higher percentagesof RAP allows the contractor to maintainbetter price stability when asphalt prices increase.The use of 10 percent RAP will reduce costsby about eight percent. According Prowelland his colleagues [1 L field trials in the U.S.have used between 20 and 50 percent RAPin warm mix asphalt. This is much higherthan the 10 to 30 percent normally used hot mixasphalt. Lower production temperatures allowthis increased RAP because the virgin binderis not aged as much and so it is better able tointeract with the RAP binder and soften it.On site experiencesIn the U.S., certain parts of the countryare designated as "non-attainment" areas,meaning that the level of certain pollutantsis above a standard set by the EnvironmentalProtection Agency. Such areas often haverestrictions placed on them to reduce pollutionduring peak hours of the day. By producing WMA,it is possible that contractors will be allowed tomanufacture mix during more hours of the day,simply because less energy is being consumedand less pollution is generated.Contractors and agencies often experienceproblems when a new layer of asphalt mixis placed over a pavement which has been treatedwith crack sealant. When the hot asphalt mix hitsthe crack sealant, it expands causing a bumpin the road. Experiences in the states of Missouri,Texas, and Wisconsin have all shownthat when the asphalt mix temperature is loweredto a temperature of around 115°(, the numberand severity of bumps is drastically lowered.Thus, warm mix is often specified for this typeof an overlay.The last three items are also very muchinterrelated. Reduced fuel usage is intuitivewhen one reduces production temperatures. »>europeanroads review 1 B • SprIng 201 1 • RGRA --


Warm Mix Asphalt in the u.s.Generally speaking, contractors report a savingsof anywhere from 15 to 77 percentwith an average energy savingsof about 23 percent. However, in order to takefull advantage of warm mix, it is best to make surethat aggregate moisture is reducedas much as possible prior to mixing.This is because each additional one percentof water in the aggregate will increasefuel consumption by about 10 percent.Also with reduced fuel consumption comesless air pollution, but it is important to ensurethat the plant burner is properly tunedso that unburned fuel does not inadvertentlycause the amount of volatile organic compoundsto increase. Reducing temperature at the paving sitewill lower the generation of emissionsbehind the paver and reduce the air temperaturearound the workers.ConclusionThese advantages explain why, in the brief spanof seven years, the production of warm mix asphaltis becoming the way the asphalt industryin the U.S. does business. According to a NAPAsurvey, a total of 16 million tons of warmmix was produced in the U.S.out of a total asphalt mix tonnage of 360 million.Within one year, that more than doubledto 36 million tons or about 10 percentof the total mix tonnage. Currently there aremore than 20 states which have specificationsthat allow the use of warm mix in the U.S.as shown in Figure 1.The Federal Highway Administrationhas made an organizational goalof having 40 states with permissive specificationsby next year.QFigure 1States that have (green) or will have (white) Permissive WMA Specifications•References[1] Prowell et al. in NAPA publication QI P 125, Warm Mix Asphalt:Best Practices, 2nd Edition, february 2011~ europeanroad s review 1 B • Spring 2011 • RGRA


lean-Paul FORTDirectorCOLAS Solutions Technical Center(USA)Glen GRAHAMRegional Manager MissouriDELTA Companies,(USA)L----------' Wa rm Mix Aspha ItInterstates 55 and 57 in Missouri170,000 tons of Warm MixPaving I-55 with Foamed Asphalt Warm MixShannon SINNQuality Control ManagerMissouriDELTA Companies,(USA)170,000 of Foamed Asphalt Mixes were placedbetween June 2009 and October 2010 in thebase and the shoulders of the 1-55/ I-57 Projectin southeastern Missouri; making it the largestWarm Mix road project ever completed to date.In addition to contract technical obligations, athorough Performance, Constructability andEnvironmental evaluation was completed byColas' operations, equipment and laboratorypersonnel. Foamed Asphalt Mix production metall volumetric and density requirements. Inaddition to reduce asphalt binder aging, lowerproduction temperatures have also beenshown to preserve polymer elastomericproperties; thus increasing pavement durability, resistance to rutting and lowtemperature cracking. Emissions at the plant were drastically reduced; energyconsumption was cut by 15%,BackgroundI-55 is the main north-south transportationartery in the Midwestern United States.This Interstate connects Chicagoto New-Orleans l,550km further south,moving through major cities such as St. Louisand Memphis along the Mississipi valley.I-57, another north-south artery between Chicagoand the South cuts short through the State of Illinoisand connects with I-55 at the north end of our project.Both highways are crucial to the freight trafficbetween the Chicago midcontinent huband the Gulf of Mexico.The project, located in Southeastern Missouri,includes the 1-55/1-57 junction and extendsto the south through New-Madrid County.The contract totalized 260,000 tons of bituminousmixes laid on 66 lane-miles (1 06km) from Juneto December 2009 and from Marchto October 2010. The structure placed overthe existing concrete slabs is composed of:• 5cm of base course, high traffic 19mmSuperpave Design using a polymer modified binder• 4cm of 12.5mm of Stone-Matrix-Asphaltsurface course,• 9.5cm of 19mm Marshall Mix for the shoulders.I-55 project was also one of the first four projectsin the nation to be awarded as partof The American Recovery and Reinvestment Act,enacted in 2009 by the Federal Administrationto stimulate the economy.The Missouri Department ofTransportation(MODOT) has taken a very proactive approachto new technologies that benefitthe environment. Delta Companies, Colas Inc.'ssubsidiary in the Midwest seizedthe opportunity to introduce one of the newestideas in the area of asphalt mix production,namely Warm Mix. Conversations were begunwith Missouri Department of Transportationofficials in the initial stages of the project.Delta Companies proposed the substitutionof 170,000 tons of base and shoulder"Hot Mix" with Warm Mix using foamedasphalt technology and committedfor those to meet all the hot mix production »>europeanroads review 1 B • Spring 2011 • RGRA ~


Interstates 55 and 57 in Missouri170,000 tons of Warm Mixcontractual requirements. As a resultof the intangible benefits that MODOTcould realize, the change orderwas quickly approved.The Colas Technical Center took advantageof the size of the project to perform a completecomparative performance evaluationof the Hot and Warm Mix productionsthrough the two paving seasons. This evaluationcovered mix performance, constructabilityand plant environmental controls.The main results are presented below.Warm and Hot mixcomparative performanceContractual mix requirements were thus closelymonitored and Warm Mix production volumetricsproperties were very consistent with Hot MixProductions ones. Similarly in the field compactionrequirements were achieved at a 30°C averagelower temperature (Table 1).During the course of the project a comprehensiveperformance testing on WMA and HMA productionswas carried out.However, the WMA noticeably higher dry initialstrength appears to account for someof the larger percentage loss value obtained.Resistance to permanent deformationIt is measured by two simulativerutting tests conducted on gyratoryasphalt mix specimens compacted tothe expected field void level (7%).Tests can also be performed on roadway cores.• The Asphalt Pavement Analyzer Test - APA(AASHTO T 340), six specimens preheatedat the regional high performancegrade temperature, 64°C, are submittedto 8,000 cycles applied by three loadedsteel wheels through 1 OOpsi I 689.5kPainflated hoses (Photo 1).I-55 - I-57HMA WMAAverage Production TO 175°C 145°CCompaction TO range160-110°C 135-100°CAverage final compaction, % Gmm 94% 94%Table 1Hot and Warm Mixes Average Temperatures and Final CompactionMoisture sensitivityThe potential for moisture damageis estimated by comparing the tensile strengthsof a dry subset and a conditioned subsetof specimens compacted at the expectedfield void level (7%). ASTM conditioningmethod D4867 was used with the freeze-thawand wet cycles. The data obtained showedthat the WMA had 81 % retainedstrength compared to 94% for the HMA (Figure 1).0Photo 1Asphalt Pavement Analyser Test• The Hamburg Loaded Wheel Test - HLWT(AASHTO T 324) measures the combined effectsof rutting, attrition and moisture damageby rolling two 72kg steel wheels directlyacross the surface of four specimens immersedin 50°C water (Photo 2).100% 1,3001,20095%1,100 'i~o 90%1,000 .r::0,""VI'"c:..... 85% 900~VI80080%700Figure 1600Tensile strength• HMA Dry Set • WMA Condo Settest data ~HMA Cond o Set • WMA Dry Set ;3ASTM D4867Photo 2Hamburg loaded Wheel TestBoth APA and HLWT tests (Figures 2, 3)evidence a significant improvement in ruttingresistance when foam warm mix technologyis used; this improvement is particularlyEll europeanroads review 1 B • SprIng 2011 • RGRA


significant with the Hamburg Loaded Wheel test.which denotes higher resistance to ruttingas well as to moisture damage.Delta I-55 SP190 PG 76-22 MAXAM TrialAPA. 45.4kg. 689.5kpa, 64°C.Number of CyclesMaster curve representations show (Figure 4)an average 10% overall decrease in E* valuesfrom the HMA to WMA production mixes.The effect that this change will haveon the pavement life calculationshas not been evaluated in MEDPGbut is anticipated to be fairly small.I:l0.0I:ll:ll:l I:ll:ll:l I:ll:ll:l I:ll:ll:l I:ll:ll:l I:ll:ll:l I:ll:ll:l I:ll:ll:l'\. ,.. .". fl.. .,. \). '\. '0.-0.5E -1.0E. -1 .5.sCo0 '"~-2.0:>or:: -2 .5-3.0-3.5-4.0-4.5Figure 2Asphalt Pavement Analyzer Rutting Chart0.0-0.5E -1.0E..s-1 .5Co0 '" -2.0~:>or::-2.5-3.0.,HlWT DElTA I-55 MAXAM WMA Trial SectionNumber of Wheel Passes- SP 190 HMA Control- SP190WMA10,000:< 1,000..4 ':X....... ,;~~Photo 3Dynamic ModulusTest~.~ ~~~ ~...pt' • HMAI-SS ~/'""~ WMAI-SS-3.5-4.0-4.5Figure 3Hamburg loaded Wheel Test Rutting ChartThe Dynamic Modulus Test (AASHTO TP 79)It measures the viscoelastic responseof the asphalt material to compressive sinusoidalstress (Photo 3). The test is performedover a range of temperatures/frequenciesthat simulates road service conditions.It characterizes asphalt material's structuralcontribution to the road structureand is the main entry in the new AASHTOMechanistic-Empirical Pavement DesignMethod (MEDPG).1001.0E-0.51.0E-0.3 1.0E-0.1 1.0E+0.1Reduced Frequencies (Hz)Figure 4HMA & WMA E* Mastercurves I-55 at 20°C reference temperatureLow temperature cracking resistanceIt was measured with the Disc-Shaped CompactTension test DC (T) (ASTM 07313)at the Advanced Transportation Researchand Engineering Laboratory in Rantoul, Illinois.The Disc-Shaped Compact Tension test. or DC (T).is a practical method for the determinationof the low-temperature fracture propertiesof 6-in cylindrical asphalt concrete specimensor road cores. The test consists in measuring »>1.0E+0.3~"0ueuropeanroads review 18 • Spring 2011 • RGRA ~


Interstates 55 and 57 in Missouri170,000 tons of Warm Mixthe Crack Mouth Opening Displacement (CMOD)of a saw-cut notch under tensile loading(Photos 4, 5). The fracture energy requiredto generate a unit cracked surface areais related to mixture's resistance to thermalcracking and is deducted from the areaunder the load-CMOD curve. Test temperatureis 10°C greater than the regional low temperatureperformance grade of the asphalt binder,i.e. -12°C here. The DC (T) specimensare easily produced from both gyratoryor road cores; this allows testing freshlyproduced mix or roadway material.This prediction is based upon fieldcracking data correlated to CMOD fractureenergy by Buttlar et al. (2010) [1]displayed in Figures 5 and 6. These resultssuggest that the warm asphalt mixturewill be more resistant to thermaland reflective cracking over its service life,than the hot mix control.600500N! ,.,E'400


Site informationOriginal PG binderRecovered from HMARecovered from WMASuperpave Performance Grade (PG)test resultsThe PG grade evaluations of the originaland recovered binders based on Dynamic ShearRheometer (DSR) and Bending Beam Rheometer(BBR) tests evidence that difference in the failtemperatures ranges is relatively small (Table 2).I-55 I-57PG 76-22 PG 76-22(80.14-23.88) (76.38-23.23)PG 82-16 PG 76-22(82.75-21.68) (77.84-24.23)PG 76-16 PG 76-22(80.55-21.33) (78.83-23.68)Table 2Performance grading information (AASHTO M320 Table 1) and continuous gradeMulti-stress creep and recovery test (MSCR)Binder Dynamic Shear testing is conductedat low levels of stress and the G * I Sin(6)criterion does not correlate well with mixturerutting when polymer modified binders are used.Recent research (D'Angelo, 2007) [2]has demonstrated the need to evaluate bindersat higher strain levels to fully capturetheir response outside the linear viscoelasticdomain, and better predict bituminousmixtures rutting. The new criteriaare the non-recoverable compliance (Jm)and percent recovery, based on binder creepand recovery testing at several stress levels.The Jm and elastic recovery were measuredat 64°( , the high regional performancegrade temperature. Results presented in Figures 7,evidence that the recovered foamed polymermodified binder has a higher elastic responsethan its "hot" counterpart, suggestingthat the "warm" binder has a betterelastomeric polymer network.~'0vGel permeation chromatographyIn order to relate the better elastomericproperties of the "warm" recoveredbinder to the condition of the SBS-Polymernetwork a comparative Gel Permeation(hromatography (GPC) was performedat the COLAS' Technical and Scientific Campusin Paris, France on(1) the original PG 76-22 binder;(2) the binder recovered from the Warm Mixproduced at 152°( ;(3) the binder recovered from the Hot Mixproduced at 182°( and(4) the binder recovered from an over-heatedHot Mix sample at 193°C.GP( allows separating molecules according totheir molecular weight; chromatogramsanalysis provides information on the averagemolecular weight of binders' componentsas well as on their size distribution.The GP( chromatograms (Figure 8) exhibittwo distinct peaks, one for the polymerand one for the bitumen. A closer lookat the polymer peak shows that from 152°(to 182° and 193°(, the polymer peaksare less pronounced and wider revealingthat with increasing temperature(1) the polymer average molecular weightdecreases and that (2) the polymer molecularweight range increases, due to degradation.These observations are consistent withthe progressive degradation of t he polymernetwork with temperature.Construction controlProvided that improved workabilityand compaction are one of the expected benefitsof warm asphalt processes, density evolution vs.compaction energy and mat temperaturewere monitored (Figure 9, Photos 6, 7). »>~~'"'" u..0.180.160.14:E 0.12vc 0.10.!l!a.e 0.080uc. 0.06..U 0.04.E; 0.020.00Tank PG76·22Rec.WMAPGRec. HMAPG;:zu '"100%90%~ 80%70%III:=E60%~.. 50%>0Ii:40%'"30%#.20%10%0%Tank PG Rec. WMA Rec. HMA76-22 PG PGFigures 7Jnr and percent recovery from MSCR test for binder used on I-55 projecteuropeanroads review 1 B • Spring 2011 • RGRA liD


Interstates 55 and 57 in Missouri170,000 tons of Warm MixFigure 8GPCChromatogramsof the binders -Polymer Peak Detail6.004.002.000.00>.. -2.00·4.00-6.00·8.00Decreasing molecular weight Ileft peak: polymerMrxa119JOCMueat 1ar cMlx at lSr cOrigIna l binder30Right peak: bitumen0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00oMat Density vs. Surface Temperature & Roller Passes94.0 ~ 5 vibratory passes2 BrNk Down rollfl'Sclose 10 each other92.0is} 90.02 Break Down rollers, gin tandem behindpaver 6 passesvibratory + 1 statkISWater is greenerSince 2005, Colas Inc. has been evaluating technically,environmentally and economically all warm mixtechnologies available: organic waxes, chemical surfactantsand the different foam technologies. Colas SolutionsTechnical Center coordinated this methodical laboratoryand field research jointly with operations, equipment,environmental and laboratory personnel.This factual evaluation evidenced that Warm Mixtechnologies have benefits in terms of mix performance,energy savings and emissions reduction; however foamedasphalt technologies stood out in terms of practicality,cost-effectiveness and low carbon footprint:no additive is greener than water. This led Colas companiesto strategically invest in foam technologies, resultingin an exponential growth of warm mix tonnage:last year 18.5% of Colas US bituminous mixeswere foamed produced; in 2011 the share is projectedto be 27.9% (see Figure 10).Figure 9Mat Densityvs. Temperature& Rollers Passes~ 88.086.084.0160 140 120AverageTemperature (0C)• HMA B 1/82 Vibr. t:=.. WMA Tandem 81182 Vib. 1:::100 8030.0% 27.9%25.0%20.0% 18.5%15.0%10.0%5.5%5.0% 3.6%0.0% 0.4".0.1%0.0%2007 2008 2009 2010 2011PWUSA • CANADAFigure 10Evolution of EcoMat (COLAS Inc. WMA trade Mark) in share of totalCOLAS US production~;3Photo 8Temperature Check(279°F - 137°C)behind the ScreedPhoto 9Density controlduring compactionThis was particularly criticalbecause these 19mm high traffic designs(PG76-22, 125 gyrations) placed in 2-inare usually not the easiest to compact.Pavers & Rollers Type: Cedar Rapids Paverwith Material Transfer Vehicle; 2 CAT CB634vibratory rollers; DD IR Finish Roller.Foamed asphalt mix refers to a bituminous mixturein which 1 % to 2% of water injected into the hot bitumen,results in spontaneous foaming and temporaryalteration of the physical properties of the binder;when foam dissipates the original properties of bitumenare regained.By foaming the bitumen temporarily:1. Expands its volume, facilitating the coatingof the cooler aggregates,2. Increases mixture workability at lower temperaturethanks to Foam's Shear Thinning qualities.Shear thinning means that viscosity decreases as shear rateincreases; it occurs in substances such as shaving creamand is crucial to its use: the cream stays put in your handbut glides smoothly on your skin under the bladeof the razor. Similarly foamed asphalt Shear Thinningproperties help maintaining a thick film of binderwithout risks of draindown when stored in the siloor when hauled in a truck, but increase its workabilityunder the shear of the screed and the compactive effortof the rollers.lIB europea"roads revIew 1 B • Spring 2011 • RGRA


Average Warm Mix density behind the screedmatched HMA's at 85% MTDbut at about 20 0 ( lower temperature(137-1400( vs. 156°(). The two breakdownrollers were moved up in tandem closerto the paver and after the fourth pass,WMA mat density matched HMA.Target 94% MTD density was achievedat an average 20°C lower temperaturewith the same compaction energy thanksto the enhanced Foam Mix workability.Plant controlsAll mixes were produced from Delta'smobile Cedar Rapids 400 tlh parallelflow plant equipped with a 70 tons surgebin (photo 8). The plant is equipped MaxamAquablack foam device (photo 9)Plant controls included temperatures checks;Oxygen O 2; emissions of (arbon Monoxide (0,and Nitrogen Oxides NO x ; as well as energyconsumption. Main results are summarizedbelow (Table 3 & Table 4).Conclusions1-55/1-57 project, the largest Warm Mixroad project ever completed to date,successfully met all contract technicalspecifications and confirmed severalof Warm Mixes' benefits: lower emissions,reduced energy consumption and enhancedconstructability. In addition the performanceevaluation conducted pointed out that not onlyWarm Mix Technologies allow reducingasphalt binders aging, but they also permitto preserve the elastomeric propertiesof the polymer-modified binders.PerformanceMix Rutting tests and binder MS(R testinghave evidenced the better resistanceof the polymer modified Warm Mix productionto large nonlinear plastic deformations.As opposed to testing in the linear viscoelasticdomain where mix and binder showed slightlylower dynamic and shear moduli, respectively.Th is differentiated response is attributed tothe lower production temperatures which(1) preserved the elastomeric propertiesof the polymer (better resistance to plasticdeformations);(2) reduced the aging of the viscoelastic asphaltbinder (lower moduli). This reduced agingalso translates into higher resistanceto low temperature cracking.June throughDecember 2009Mix Tons Av. Mix TO Av. Agg. Moist (%) Av. KBTUs(1)/tonHMA 85,467 175°C 1.8 241WMA 70,644 149°C 1.7 205156,11 1 -26°C -15%II) A BTU (British thermal unit) is the amount of heat required to raise1 pound (454g) of water. 1 degree Fahrenheit (O.55' C)Table 3Energy Consumption on 2009 I-55 ProductionAv. HMA Av.WMA I':..Mix chute TO 177°C 153"CCO ppm 1308.0 465.2Table 4HMA, WMA productions comparative CO emissionsConstructabilityThanks to foamed asphalt increased workabilitydensity goals were met at 20 0 ( lower temperaturewith the same compaction energy as hot mixes.Emissions & EnergyMeasures on I-55 production showedthat an average 30 0 ( temperature drop resultedin a 64% Carbon-Monoxide ((0) reductionand 15% Energy Savings . •111 Bunlal. W.G .• Ahmed. S .• Dave. E. V. and Blaham, A. f. (2010)."Complehensive Database of Asphalt Concrete fracture Energy and Links tofield Performance," Paper presented at the 89th Annual Meeting of theTransportation Research Boa rd, Washington, D.C., January 20 10[2[ D'Angelo, J., Klunz, Robert Q, Dongre, Raj, and Stephens Keith ., "Revisionof the Superpave High Temperature Binder Specification: The Multiple StressCreep Recovery Test," Journal of The Association of Asphalt PavingTechnologists, Vol. 76, pp. 123, 2007Photo 8-24°C-64%0Delta CedarRapid Mobile Plantwith Water TankPhoto 9Maxam AquablackFoam Device0european r o a d s review 1 B • Spring 2011 • RGRA &I


Juan A. GONZALEZ LE6NR&D EngineerCECAIARKEMA(France)Sandrine lIGIERR&D Technician(France)lionel GRAMPR~R&D TechnicianCECAIARKEMA(France)Paving of a WMA mixture produced with Ceca base RT~ additivesGilles BARRETOSurfactant R&D ManagerCECAIARKEMA(France)- --I Warm Mix ASpha@Warm Mix Asphalts (WMAs)with chemical additivesWarm mix asphalts (WMAs) are produced, laidand compacted at lower temperatures thanthose usually required for hot mix asphalts(HMAs). Several WMA techniques, based ondifferent physical processes and additives, arealready available on the market.Here it is described one specific technique, basedon a chemical additive, to produce WMA(Cecabase RT®). The use of this chemical additiveallows the reduction of about 40°C of the standardhot mix asphalt production temperature.They are liquid additives that are simply addedinto the bitumen at concentrations from 0.2 to0.5 wt% with respect of bitumen. Observationssuggest that these additives act at the mineral aggregate/bitumen interphase, in ananalogous way to a surfactant that, as shown in this article, does not change thebitumen rheological properties.Through laboratory tests and actual field jobs the ability of this additive to produceWMA is demonstrated over a wide range of binders, mineral formulas and productionand compaction conditions. The several advantages ofWMA, and more particularly ofthis additive, from the industrial, and environmental point of view are also discussed.IntroductionDuring the past years, there has been an increasinginterest on the area of WMA. WMA are producedat temperatures below the regular temperaturesused in hot mix asphalts (HMAs).There are already several techniqueson the market that allow producing WMA [1-3].The existing WMA technologies may be separatedinto 3 different groups:• A first group where given quantity of wateris added into the mixture, by means ofwet aggregates, mineral additivesor direct injection, to be vaporizedwhen in contact with hot bitumen to form a foam.This foam, of lower viscosity than the bitumen,allows the covering of the aggregatesat reduced temperatures.• The second group of technologies are based onthe addition of solid additives to the bitumenin order to reduce its viscosity. These additivesare mainly wax based materials with fusiontemperatures around 1 aaoc that makethe bitumen and the mix more workable,allowing compaction at lower temperatures.• Finally, the third group of technologies is based onliquid chemical additives, which do not generatea bitumen foam or change the viscosityof the bitumen, but provides enough workabilityto produce and compact warm mix asphalts.The additives studied here belong tothe third category. This kind of additivesare capable of reducing the mix productiontemperature without any water addedor reduction of the bitumen viscosity.~ europeanroads revIew 1 B • SprIng 201 1 • RGRA


They are usually used at lower dosagesthan wax-based additives (about 0.5% in weightrelative to the bitumen). They can be liquid at roomtemperature, which simplify their use.They may be added to the bitumenbefore or during the asphalt mixing processwithout any significant productionplant modification.In this article, the effect of the liquid chemicalsadditives commercialised by CECA, under the nameof Ceca base RT®, to the bitumen and the asphaltmix is presented. The related propertiesand advantages of their use for the productionof WMAs is discussed.Additive effectsEffects on BitumenBituminous compositions comprising O.3g and O.5gof the additive in 100g of a 35/50 [1/1 OmmJpenetration bitumen at 160°C were preparedunder low shear mixing for 10 minutes.As can be observed, the bitumen viscosityremains practically unchangedthrough the whole range of temperaturestested, 160-80°C. These additives,in contrast to paraffin based additives,do not depend on a bitumenviscosity decrease at high temperaturesto provide workabilityto the final asphalt mixture [3.4J .Standard penetration and Ring & Ballmeasurements were also carried outon different bitumens, includinga polymer modified bitumen (PM B),with and without the chemical additivefor WMA production. In each case,0.5% of the additive relative tothe mass of bitumen was addedto the bitumen using the same procedureas described above. The additivedoes not change the grade of the originalbitumen, resulting in similar valuesfor penetration and R&B temperatureas can be seen on Table 1.50/70 50/70 BitumenBitumen +0.5% additive30/45Bitumen30/45 Bitumen SBS modified+0.5% additive BitumenSBS modifiedBitumen+0.5% additivePenetration(1/10mm)51 50Ring & Ball 51 .2 50.8(0C)3354.237 5253.6 57.85657.2«:.:OJTable 1Penetrationand Ring & Ball valuesof different bitumenswith and withoutchemical additive'"~~' ';;0OJ:> '"10010A dynamic shear rheometer with temperaturecontrolling capabilities was used to measurethe viscosity of bitumens with and withoutthe before mentioned chemical additive.Figure 1 shows the rotational viscosityas a function of temperature at a constant shearrate of 100s" for pure bitumenand the two bitumens with additive.- Pure 35/50 1I10mm bitumen• + 0.3% additive• + 0.5% additiveEffects on asphalt mixtureThe laboratory Baustofflabor Hamburgin Germany carried out a series of testson asphalt mixtures to comparethe workability of an asphalt mixtureprepared with and without the before mentionedadditives at regular HMA and WMA conditions.The HMA and the WMA mixtureswere prepared following the same formulaas described in Table 2.»>Weight percentage (%)5/8 aggregates 312/5 aggregates 350.180100 120 140 160Temperature (. C)Figure 1Viscosity of 35/50 [1I10mml bitumen with and without chemical additiveCrushed sand 0/2 graywacke 29Filler (limestone) 550/70 Bitumen 5.9 ~OJTable 2Mineral formula used for laboratory studieseuropeanroads review 1 B • Spring 2011 • RGRA IIi:D


Warm Mix ASPha ~Warm Mix Asphalts (WMAs)with chemical additivesE ...z-; 280.,.:>.2 260The asphalt mix containing the additivewas prepared by adding 0.5 weight %of the additive to the bitumen,which was stirred for about 15 minutesbefore mixing it with the previouslyheated aggregates.The workability measurements were carried outusing a method developed in Gemanywith the collaboration of BaustofflaborHamburg (5). The test is based onmeasuring the torque of a rotational deviceintroduced into the asphalt mixture,simulating the movement of the mixthrough the paver during spreadingand laying of the mix at a given temperature.Figure 2 shows the results of torquefor the different asphalt mixtures,with and without additive, at 120 0 (and 160°C. The mix without additive goesthrough a large increase in torquewhen the temperature was decrease by 40°(,going from 292Ncm to 318Ncm.The mix with the additive already startswith a lower torque, higher workability,at 160 0 ( and reaches a torque of 290Ncm,which is quite similar to that measuredby the non-additivated mix at 120°C.These measurements showed that the testedadditives do have a positive impacton the workability of an asphalt mixture.This effect is not only attained at reducedtemperatures, as use to produce and pavewarm mix applications, but is also obtainedat higher temperatures. As it will be discussedbelow, this can result in other practicalapplications for this kind of additives,such as increasing the hauling timeof an asphalt mixture or simply enhancingthe workability of a difficult HMAwhen needed.320 ,---------------------~==~----------~300 +-----------------------Further tests were carried outon these asphalt mixtures to completethe study. Rutting tests on plaquesof asphalt mixture with and without additiveproduced at 140 0 ( were carried outon a Hamburg wheel test.The asphalt mix plaques were submergedin water at 60 0 ( during the 20,000 cycles tested.The results showed that the values of ruttingbetween the two samples were very close.The mixture that didn't contain the additiverut 4.4mm and the one containingthe additive rut 3.8mm. These results indicatethat the enhancing effect of the additiveson the mix workability at higher temperatures,do not degrade the final properties of the mix,as has been shown in previous publications (6).Given the low dosages of additive used,compared to the mass of bitumen,it is likely to believe that these additiveswork only at the interfaces between the bitumenand the mineral aggregate at the momentthey are placed in contact during production.This assumption seems reasonablegiven the surfactant nature of the chemical additivesused. The presence of these chemical additivesat the interface must play an important rolein the covering process of the mineral aggregateby the bitumen during the production process.By decreasing the surface tensionbetween the bitumen and the aggregate,the additives could compensate for the higherbitumen viscosity at lower temperatures,allowing a complete coverage.However, this is not enough to providethe workability observed by the useof these additives. The presence of the additivesat the bitumen and mineral aggregateinterface should play an important roleon the frictional forces between the elementsof the asphalt mix and how the applied forcesare distributed during compaction.In addition, the presenceof these additives at the interfacemay also help with the overall adhesionof the bitumen to the mineral aggregates,as was observed in water resistance tests [6, 71.where the cohesion of the conditioned samplewas significantly improved.240Referenceasphalt mix160·(Asphalt mixwith 0.5%additiveReferenceasphalt mix120·(Asphalt mixwith 0.5%additiveFigure 2Workability of asphalt mixtures with and without the chemical additiveat the indicated temperatures~ europeanroads review 1 B • Spring 2011 • RGRA


Example Field JobsA few examples of WMA field jobsthat had been carried out by using the additivesdescribed above are presented here.A field test was carried out in Francefor a rolling surface. 500 tons of BBSG 0/10 mix,(beton bitumineux semi-grenu) were producedfor a two lane road on an industrial area.The asphalt mix formula used contained10% of recycled asphalt pavement (RAP)and 5.4% of bitumen with a penetration gradeof 35/50 [1/1 Ommj . Only 3kg of additive per tonof bitumen was used (about 160g of additiveper ton of asphalt mix). The asphalt mixwas produced at a temperatureof about 135°( and was placedand compacted, after a hauling time of 40min,at a temperature of 125°( in the same wayas a standard HMA. Density measurementstaken during the pavement operation(40 measurements taken bygamma densimetry) showed that an averagedensity of 2.367t1m 3 was achieved.This value is well between the requireddensity limits for this kind of pavement(2.406t1m 3 > density > 2.312 tlm 3 ).Roughness measurements also showeda correct value. This job was in factcarried out next to a previous WMA test jobwhere a similar BBSG asphalt mix formula,without the recycled asphalt pavement.After two years of use, the previous sections,a WMA and comparison HMA,are in perfect conditions.A road construction job of 3,600 tonswas for a heavy traffic two lane roadof an asphalt mixture denominatedEME in France (enrobe a module eleve)was produced at lower temperatureswith the used of the before mentionedliquid chemical additives.This asphalt mixture formula is usedas a base layer capable of withstandingheavy traffic. The EME is characterized due tothe lower penetration grade of its bitumen,10/20 [1/10mmj. For this joba 10cm thickness layer was paved.The chemical additive was addedduring the bitumen-storing tank fillingat 0.4 wt%. The asphalt mixturewas produced at a temperature of 130°( ,where regularly is done at 170°(,The laying down and compaction operationstook place at temperatures below 130 0 (without any problems. Density measurements(approximately 25 measurement per laneshowed that an average valueof void percentage of 4.3% was obtained,with a 100% of measurements below 8%.The required maximum average void percentagewas 6%, with 95% of the measurementsbelow 8%. Laboratory studies also showedthat the Duriez test for this formula(water damage resistance test),at the warm mix asphalt conditions usedin the field job, gives a ratiobetween the conditioned and dry specimensof 0.78 (where a value higher than 0.7 is required).A 8km section of rolling surface for a Frenchhighway was also carried out at warm asphaltconditions by using the discussed chemical additives.In this case, an asphalt mix formula coinedBBTM (beton bitumineux tres mince)was used. This kind of surface is placedfor heavy traffic on a very thin layer,about 2 to 3cm in thickness.The BBTM contains a polymer-modifiedbitumen (PM B). The mix was producedat 130 0 ( and placed at 120°(,while compaction took placeat about 11 OO( (given the small thicknessof the layer, cooling kinetics are faster).This kind of mix is usually doneat a temperature of about 170 0 ((because of the polymer modified bitumen).No problems were encounteredduring the production of paving. Laboratorystudies done before starting the jobdemonstrated that the asphalt mix carriedat the lower temperatures complied withthe requirements (void % and rutting) .A Duriez test showed a ratioof the conditioned sample to dry sample of 0.92.Photos 1 and 2 show the job during paving. »>Photos 1 and 2Paving of a highway section in France using warm mix asphaltsproduced with chemical additiveseuropeanroads review 1 B • Spring 2011 • RGRA IIIIiD


Warm Mix Asphalts (WMAs)with chemical additivesMany other successful jobs usingthe same additives had been done in Europeand over the world, for example in Argentine,Australia, Japan, US and Canada.They have been carried out on different asphaltmix formulas under different pavingconditions, demonstrating the versatilityand robustness of the liquid chemical additivetechnique for MWA.Observed Propertiesand AdvantagesThere are several advantagesof reducing the production temperatureof asphalt, which have beenalready discussed in previous publicationsand conferences [1 -3] .Here, some of these advantagesthat have been observed (and quantified)when using the kind of additives describeabove are presented.Energy savingsOn a field test carried out in Polandthe actual energy consumptionsof a HMA and a WMA were measured.The comparison was doneon a 0/20 base layer with 4.7% of bitumen.About 200 tons of asphalt mixturewere produced at standard conditions (150°C)and 160 tons at warm mix conditions (125°C)with 0.5 wt% of additive.The gas consumption during the wholeproduction was measured in both cases.For the HMA 6Am 3 of gas per ton of mixwere consumed, while for the WMAthe consumption was decreaseto 5.1 m 3 of gas per ton of mix.This is a reduction of 20% for only 25°Creduction in the asphalt productiontemperature, a higher energy savingwould be expected when the temperatureis reduced by 40°C as in some of the fieldjobs described above.Higher production ratesOne straightforward way to reducethe temperature at which aggregatesare heated to produce a WMA is to reducethe drying drum burner setting.A large reduction in the burnersetting can lead to instabilities of the burningwith a negative impact on the emittedpollutant [8] . However, if the rateof production is increased,thus forcing the aggregates to staya shorter time in the drying drum,it will also contribute to reducethe temperature. WMA productioncan result in an increase of asphalt mixproduction capacity since the aggregatesgo through the drum in less time. In a job,where a WMA BBTM was being produced,the plant worked at a rate of 280 tons/h,while for the regular HMAit was of 210 tons/h, thus an increasein productivity of 30%.Lower pollution emissionsMeasurements of the emissions at the exitof the chimney of the production plantwere carried during a BBTM production,in regular HMA and WMA conditions,following standardized proceduresin France. The results, expressed in the massof pollutant per ton of mix producedare shown in Table 3.Significant differences were observedbetween the measurements,with reductions between 14 and 36%of the different pollutants. A reductionof about one third of the CO producedwas obtained with the reduction of 40°Cin production. Important reductionswere also observed for other pollutants,such as N0 2, the volatile organiccomponents (VOC) and the dustparticles emitted.Fumes DustCO CO 2 VOC N0 2T (0C) (gITon mix) (gITon mix) (kgITon mix) (gITon mix) (gITon mix)WMA (125°C) 97 5.4 69.8 13.4 8.5 21 .4HMA (170 o q 125 7.4 109.6 15.6 10.7 31 .2% Difference -22% -27% -36% -14% -21% -31% ~uTable 3Gas emissions comparisonIia europeanroads review 1 S • Spring 2011 • RGRA


170160E 150.. 140~ 130! 120~ 11010090..Q."Longer hauling timesThe parameter that dictates the timeallowed for the transportationof the produced asphalt mixtureis the temperature at which the asphaltcan still be laid and compacted.The mix will cool down during transportand should be used before the mixhas become too hard to be laidand compacted. The cooling rateof an asphalt mix during transport(or during a waiting time), meaningthe amount of heat lost as a functionof time, is directly proportionalto the difference between the mixtemperature, T mix' and the surroundingstemperature T amb. Even from this very simplifiedrelationship, it can be seen that,at equal ambient temperature,the higher the asphalt mixturetemperature, the faster it will cool down(larger amount of heat lost per unit of time) .A simple experiment was carried outin the laboratory to demonstrateand quantify this difference. Samplesof a BBSG 0/10 (which is a friction course)with a 35/50 111 Omm bitumenwere produced at 165°( and 115°(to follow their cooling kinetics.A thermocouple was placed at the middleof the asphalt mix on a coveredcontainer that was isolatedon the bottom and on the sides to slowthe cooling kinetics. The measuredtemperatures as a function of timeduring the cooling of the mixesare shown in Figure 3.It can be seen that the initialcooling slopes of the two curves,the one that starts at 165°(named HMA and the other that startsat 115°(, WMA, are different.The WMA resembles, as expected,to the final section of the HMA curve.80o 50 100 150 200Time (min)Figure 3Cooling kinetics of a laboratory asphalt mixture..... WMA-............~ HMA-.......... . c::;-f' "-.,..,- --~ ---...~ ~A linear regression was calculatedfor the initial part of each curveand the slopes were calculated.The HMA has a slope of - 0.49°(/min(between point A and B) while the WMAhas a slope of - 0.29°C/min(between point ( and D),showing clearly the differencein cooling kinetics.Assuming that for this type of mixa typical laying temperature limitfor a HMA is around 135°(,it can be considered that a HMAhas about 60 min (point B)to be transported, laid and compacted(under this laboratory kinetic studyconditions) . A WMA, fabricated at 115°(with the kind of chemical additivesdescribed in this work, with a limitof compaction of about 95°((point D) would have 75min to be transportedand compacted. This 25% increasein hauling, although considerable,is not the maximum that can be obtainedby using chemical additives. If an asphalt mixtureis produced with a bitumen containingchemical additives for WMAbut produced at HMA conditions,for example in this case 165°(,it could be transported up to the samecompaction limit for a WMA, 95°C.This would largely increase the hauling timeof an asphalt mixture, for the givenlaboratory example, it will be of 170mininstead of 60 minutes.Another advantage related tothe slower cooling kinetics of a WMA,is to pave at lower ambient temperatures.Similarly to the longer hauling time,the presence of a chemical additivethat improves the workability of the mixat lower temperatures would compensatefor the faster cooling kinetics of a cold day.One field example of the ability of WMAto be paved under cold weather conditionstook place in the city of Volzhsky, Russia.The project took placeduring November of 2008,where approximately 2,000 tons of WMAwere placed during 15 days.The 0/20 asphalt mix contained 6.5%of a 60/90 111 Omm bitumencontaining 0.3% of a (ecabase RT additive.The asphalt was producedat an average temperature of 135°(and paved at 120 0 ( on average.The weather conditionsduring the whole project were cold,with an average temperature of 6.5°(, »>europeanroads review 1 B • Spring 2011 • RGRA &I


Warm Mix Asphalts (WMAs)with chemical additiveswith a couple of dayswhere the temperature descended down to 2°(,In addition, there was between 25 to40 minutes of transportationfrom the production plant to the job site.During these cold days the asphalt mixwas placed at 110°C without any problems.The laboratory results from samplestaken during the job werewell within the specifications requiredfor this type of mix.An air void percentage of 3.3%was obtained, where the specificationrequires a value between 2.5 and 5.The Indirect Tensile Strength (ITS) ratioswere also measured, beingalso above the specifications(3.6 MPa on average for 2.2 MPa required) .Water resistance tests were also carried outand a ratio between the water-conditionedand the dry samples of 0.92 was observed,being also higher than the requiredvalue of 0.8.It is to be noted that the ability to produceasphalt mixtures at HMA conditionsfor their use after a longer time, as a WMA,may not viable with all the presenttechnologies. The techniques based onwater evaporation for foaming normallywork around the evaporation temperatureof water, 100°C (212 °F), and may haveissues with the foam formationand water evaporation at higher, standard,hot mix asphalt temperatures.longer mix hauling timesand cool weather paving.As the warm mix asphalt techniqueis gaining acceptance and peoplehave a broader experience of it,more research work should be carried outto further optimize the additives.For instance, a new generationof additives for warm mix asphaltproduction has been launched this yearby CECA, with improved storage stabilityan environmental profile(considerable less odour of the mix compared tosimilar surfactant-based products availableon the market, biodegradableand not classified harmfulfor the environment) . •ConclusionsIt has been shown that the use of the additivesstudied here, at the concentrationsrequired for the production of WMAs,is simple and does not changethe grade characteristics of the bitumen.Through laboratory tests and fieldprojects it was observed that this kindof additives does have an important effecton the workability of an asphaltmixture. It is suggested that giventhe surfactant nature of this additivesand the low concentrations requiredto achieve the effect, they interactat the interphase level between the bitumenand the mineral aggregate.Industrial scale tests and actual constructionprojects were cited as examplesto demonstrate the advantages of usingthe Ceca base RT additive for warm mixproduction, such as: production energysavings, reduction of polluting emissions,increase in mix production rates,111 D'Angelo J. et a/. Warm·Mix Asphalt: European Practice. ReportFHWA·PL·08·007 February 2008121 Presentations shown at the International Conference on Warm-MixAsphalts, Nashville TN, November 2008131 Prowell, 8.0., Hurley, G.C "Warm mix Asphalt: 8est Practices"QIP-125. NAPA, 2007141 Hurley, G.C and Prowell 8.0. "Evaluation of Sasobit® for use in warm mixasphalt". NCAT Report 05-06; National Center for Asphalt Technology.Auburn University, Auburn. AL. June 2005151 The method is explained on the official guidelines for Warm Mix AsphaltMix. published by FGSV. Road and Transport Research Association,Germany 2006161 Grampre, L, Gonzalez-Le6n, J,A. and Barreto, G. « Enrobes tiedespar additivation chimique •. Revue generale des routes et des aerodromes(RGRA), nO 866. avril-rnai 2008, pp 44-50171 Gonzalez-Leon. J, A., Grampre. L., Barreto. G. "Warm mix asphaltswith low dosage chemical additives" CD-ROM. Transportation ResearchBoard of the National Academies Washington, D.C 2009181 Paranhos, R., Jullien, A., de la Roche, C. Moneran, P .• Sautet, K.and Lombardi. B. (2008) "Multi-scale approach of emissions produced ina drum mixer hot mix asphalt plant". 4th Eurasphalt and EurobitumeCongress proceedings, 500-053, 2008E:I european roads revIew 1 B • Spring 201 1 • RGRA


Sundaram lOGARAJBusiness Development ManagerAkzoNobel Surface Chemistry(Americas)Mark SMITHHot Mix SpecialistAkzoNobel Surface Chemistry(EMEA)Alan JAMESResearch ManagerAkzoNobel Surface Chemistry(Americas)Mats NOREllBusiness DevelopmentManagerAkzoNobel SurfaceChemistry(EMEA)L-----I Warm Mix AsphaltDevelopment of a newWarm Mix Technology offeringenhanced Asphalt PropertiesToday, environmental and safety concerns, not only economic factors are driving newdevelopments in the road construction industry. One of these developments is warm mix- manufacturing and paving bituminous mixtures at lower temperatures.Akzo Nobel has introduced a new approach to warm mix and this article details theresearch and testing carried out in independent and governmental laboratories and roadtrials in USA and Europe with the chemical additive Rediset WMX. The concepts behindthe product are described.The studies have shown that the Rediset WMX additive can provide multiple effects.Mixing and compaction temperatures can be lowered by 20-30°(, which leads to areduction in fumes at the mix and paving sites, and also reduces energy consumption andthe associated carbon dioxide emissions. The original binder rheological properties asmeasured by the Performance Grade (PG) are maintained. Mixtures prepared from treatedbitumen showed improved moisture resistance and improved resistance to rutting inlaboratory tests. These results predict longer-lasting pavements and associated benefitsin whole life costing.In the winter and spring of 2009, an extended production with the product confirms thegood performance in cold weather paving over a three month period.IntroductionA reduction in the temperatureof production of asphalt mixes providesenergy savings, reduces asphalt oxidationand will also reduce emissions at the mix plants.Reduction in paving temperatures extendsthe paving season, reduces exposureof workers to harmful fumes and expandsthe geographical area that each hot mix plantcan serve.A variety of techniques have been recentlydeveloped and the processeshave collectively become known as "warm mix" .There are perhaps 15 different warm mixsystems in the market and the techniquescan be divided into four groups:Modifications to the Mixing Plantand Process; Foam Mix Systems;Modification of bitumen by i.e. waxes;and Chemical Additivesof a Surface Active nature [1-3).The ability to produce and pave mixesat reduced temperatures has been clearlydemonstrated and hundreds of thousandsof tons of warm mix have been produced,but nevertheless there remainsome outstanding issues. Because of lower mixtemperatures, especially in continuousdrum-drier mix plants, warm mix systemsmay have to cope with insufficientlydried aggregates and in particular those systemswhich rely on the foaming of asphaltby the introduction of water need to showthat the water in the system, absent in hot mix,does not cause damage either by strippingor through a detrimental effecton the cohesion of the asphalt mastic.As little as 0.3-0.9% water in the mixturecan have an adverse effect on mixstabil ity [4,6) and water resistanceis adversely affected [4, 5, 6) so the presenceof residual water in some warm mix systemsis a matter of concern. »>europeanroads review 1 B • Spring 2011 • RGRA BII


Development of a new Warm Mix Technologyoffering enhanced Asphalt PropertiesLower mix temperatures result in reducedoxidation of the bitumen in the mix process itself.On the other hand some wax-based additivesmay maintain or even enhance the stiffnessof the asphalt mix at normal pavementtemperatures [7] but with potentiallynegative effects on the low temperatureproperties of the treated bitumen [7, 8].However field and laboratory studieson warm mix themselves, as opposed tothe bitumen alone, has not demonstratedproblems in the low temperature propertiesof warm mixes based on waxy additives [9] .The Rediset WMX conceptIn 2007 AkzoNobel introduced a new warm mixsystem called Rediset WMX in an effortto mitigate the perceived deficienciesof then current warm mix technologies.In particular the system was designedto solve potential problems with the effectsof water on warm mixes; the reduced stiffnessin warm mixes compared to hot mix;and with the uncertain low temperatureproperties. The article describessome of the first results from morethan ten trials as well as commercial useof the product.Rediset WMX falls in the groupof so-called "chemical" asphalt modifierswhich do not involve the addition of waterto the system. Rediset WMX comprisesa dry chemical additive in solid pastillatedform which is added to the bitumenbefore or during the mixing process. The aminetechnology of the productprovides active adhesion promotingproperties (the ability to displace waterfrom the surface of damp aggregate)and anti-oxidant effect, while the physical formof the product provides some viscosityreduction at mix temperatures but stiffeningat pavement temperatures. The "warm mix effect"is thought to result primarily from the surfaceactivity of the amine surfactant,either from a lubrication effect on the aggregatesurface or a dispersant effecton the asphalt mastic.The Rediset product is blended into the bitumenbefore mixing or can be addedjust as the bitumen enters the mixer.The treated bitumen can be stored for 2 weeksbefore use. No changes in the mixeritself are required . One advantage claimedfor the Rediset product which sets it apartfrom other "dry" chemical modifiers,is that it improves adhesion - eliminatingthe need for separate additions of adhesionpromoter or lime.The Warm Mix EffectThe warm mix effect is the lowering of mixproduction, paving and compactiontemperatures compared to mixesmade with untreated bitumen.Compaction tests performed by NCAT(National Center for Asphalt Technology)at Auburn University laboratoryusing a vibratory plate compactor (Figure 1)show higher densities are obtainedcompared to untreated asphalts...,7.06.5'"~~5.5


Mix temperature, °CCore density Relative compaction % Relative compaction %ASTM 02726 Hveem density Rice Density116 2.327 96.0 92.2132 2.339 96.6 92.7149 (no Rediset) 2.286 94.0 90.6Table 1Field Densities from Chico. CA. PG 64-1 0 asphalt with and without 2% RedisetWMX (bais bitumen) in V, inch medium mixto Caltrans specifications (Densities are average values from 4-6 field cores)0Figure 2Field Densities, Lufkin, TexasOnly Rediset WMX treated asphaltreached compacted densities comparable tothe untreated control at normal temperatures(Figure 2).Warm Mix: 225-240°FOther Warm Mix TechnologiesFuel savingsRedisetDuring a November 2008 trial at Skanskain Sweden, in conjunction withthe Swedish Road Authority, SRA,fuel consumption at the hot mix plantwas monitored and showed clearlya 2.5 liter/ton of mix saving (about 30%total fuel saving at this plant) as well asthe consequent reduction in CO 2 emissions.This reduction in fuel consumptionis a consequence of the lower mixtemperatures and is similar to that seenwith those other warm mix systems providingsimilar reductions in mix temperature.Effect of Rediset WMXon binder rheologyBitumen in North America are specifiedin terms of Performance Grade (PG).oThe system defines upper and lower pavementtemperature boundaries on the basisof rheological tests on standardand aged bitumen binder.The high temperature boundary is related tothe resistance of the bitumen to permanentdeformation, whereas the lower temperatureis related to the ability of the bitumento resist thermal cracking.Table 2 shows some typical results.In general Rediset treated bitumenshowed little change in PG compared tountreated bitumen. In some casesthere were small increasesin the upper PG and/or reductionsin the low temperature grades representinga reduction in the temperature susceptibilityof the bitumen.One mechanism proposed for the warmmix effect, especially with waxes,is that the additive lowers the viscosityof the bitumen at the mix and compactiontemperature (Figure 3) [9J . This minor changein viscosity does not explain the abilityto lower the mixing and compactiontemperature > 30°C.Traditional binder tests show small effectsfrom addition of Rediset WMX. Typicallypenetration is slightly reduced (Figure 4),and softening point slightly increased.The Rediset WMX product is not volatileand properties like the flash pointof treated bitumen have not been affected.Hamburger Wheel Tracking TestWarm mix containing Rediset gave improveda water resistance to the mixtureand it is also seen that the use of Redisetdoes not have a negative effecton the unconditioned mix strengths.This is confirmed by Wheel Tracking testsaccording to EN 12697 performedon dense binder course samples preparedfrom the plant mixes.»>europeanroads review 18 • Spring 2011 • RGRA DI


Development of a new Warm Mix Technologyoffering enhanced Asphalt PropertiesPG 76-22PG 76-22PG 64-22PG 64-22+ 2% Rediset + 2% RedisetOriginal binderG*/sin () at 10rads/s kPa at 76°( or 64°(1.17 1.03 1.05 1.43Phase angle degrees at 76°( or 64°(73.8 72.0 88.3 84.8RTFOT ResidueG*/sin () (kPa) at 10 rad/sec,kPa at 76°( or 64°(2.49 2.25 2.51 2.88PAV ResidueBBR s, 60s, MPa at -12°(185 140 200 122Table 2PG grading of Redisettreated binders.2,0% treatment level.Selected Itemsfrom PG testingBBR m, 60s at -12°(PG grade determined0.316 0.344 0.337 0.36376-22 76-22 64-22 64-220.;~;;;~If.10,0001,00010010........ No Rediset- ... 1% Redi.e'-*- 2% Redi.e'0.1 l---______ -_-~-~-_-_-_Iso 60 70 80 90 100 110 120 130 140Temperature 'cFigure 3Viscosity of Polymer Modified Bitumen (PmB) treated with RedisetoThe results in Figure 5 show data for Texas Type Dsurface course with 5.2% PG 70-28 bitumen .Mixes containing Rediset additivegave results comparable to hydrated limemeaning that lime need not be includedas adhesion promoter in mixtures containingRediset WMX treated bitumen.On the other hand, trials in Texas and Swedenhave demonstrated that Rediset WMXis fully compatible with lime or cementand will allow lower mix and compactiontemperatures when these adhesion promotersare used.u858075:c 70cof 65605550-.....-..~o--------Figure 4Penetration of Bitumen Treated with Rediset• 701100 peno 501100·75 (4.5% SBS)----- ----% Rediset WMX23o12E 10Ec-0.~..E.ec864I2% lime basis mixI2% Redisetbasis bitumenIn the Hamburg Wheel Track Test,compacted specimens are subjected to repeatedloaded wheel passes while submergedin a warm water bath (50°C). The test evaluatesthe resistance of the mixtureto deformation (rutting) in wet conditions.2o +-.L-__Figure 5Hamburg Wheel Tracking Test at 50' CoBI european roads review 1 B • SprIng 2011 • RGRA


Texas Type D surface course with 5.2%PG 70-28 bitumen. Figure 5 shows deformationafter 20,000 cycles.Stone Mastic Asphalt (SMA) is a tough mixwith plenty of stone to stone contactwhich gives good resistance against deformationbut sometimes makes it difficult to compact.In a October 2008 trial at Beaumont, Texas, SMAsections using Rediset WMX alloweda reduction of 80-1Q0°F in mixing and 55-75°Fin paving temperature while reaching designdensity, which meant bonus paymentsfor the contractor.ConclusionsThe various trials and commercialapplication of the Rediset WMX systemover the last two years have confirmedthat the product offers warm mix effectwith additional benefits in improved waterresistance of the mixtures. It adds a ruttingresistance effect. Binder propertieswere maintained or improved. Viscositymeasurements on the binderalone do not fully predict the lowertemperatures of mixing pavingand compaction achieved in the field . •References11] Brian Prowell, Warm Mix in Europe. Hot Mix Asphalt Technology.September/October 2007121 Egbert Beuving. The Use of Warm Mix Asphalt in Europe. 20th PAPASeminar "New Technologies of Road Infrastructure" 22·24 of April 2009131 M.Acon, Warm Mix in the USA· State of the Practice, Eurobitume 2008,paper 500·05814] Joelle De Visscher et ai, Asphalt Production at Reduced Temperatures andthe Effect on Performance, ISAp, 2008151 Andrea Kvasnak, Randy West, Jason Moore, Pamela Turner, Jason Nelson,Nam Tran, Case Study of Warm Mix Asphalt Moisture Susceptibility inBirmingham, 2009 Annual Meeting of the Transportation Research Board16] feipeng Xiao, Jayson Jordan, and Serji N. Amirkhanian, laboratoryInvestigation of Moisture Damage in Warm Mix Asphalt Containing MoistAggregate, 2009 Annual Meeting of the Transportation Research Board17] Viva Edwards, Influence of Waxes on Polymer Modified Mastic AsphaltPerformance, Eurobitume 2008, paper 401·014181 Professor Walaa S. Mcgawer P.E., and Alexander J. Austerman,laboratory and field Evaluation of Warm Mix Asphalt Technology, ISAP 2008,173·184191 Viva Edwards, Influence of Waxes on Bitumen and Asphalt ConcreteMixture Performance, Eurobitume 2008, paper 401·013europeanroads revew 1 B • SprIng 2011 • RGRA ED


Hugo M.R.D. SILVAPhD, Assistant Professor, C-lACUniversity of Minho(Portugal)Joel R.M. OLIVEIRAPhD, Assistant Professor, C-lACUniversity of Minho(Portugal)- ---{ Warm Mix AsphaltAn evaluation of unusualWarm Mix Asphalts producedwith wax additivesPhoto 2Sasobit® wax additive used in this study to produce the WMA mixturesThere are several technologies to produce WarmMix Asphalts (WMAs), namely by using water,surfactants, and organic or wax additives toaffect the temperature reduction. A particularwax additive (Sasobit®) was studied in this work,which reduces the viscosity of the binder above100°(, while notably increases the stiffness atoperating temperatures. The main objectiveof this study was to assess whether it would bepossible to produce both high modulus (HMBM)and high flexibility (HFBM) bituminous mixturesby adding a wax to base bitumens softer thanthose normally applied in suchmixtures(i.e. 35/50 wax modified bitumen vs. 10/20 penbitumen - HMBM, and 160/220 wax modified bitumen vs. 50170 pen bitumen -HFBM). The optimum additive content and the reduction of temperature wereselected based on the properties of the binders. Finally, performance tests werecarried out on the studied mixtures, being possible to conclude that the use of waxesreduced the production temperature of both WMA mixtures by 30-40 0 (, maintainingor even improving some properties of those mixtures.IntroductionGeneral Hot Mix Asphalt (HMA) is producedat temperatures between 140 and 160°(,and even higher mixing temperaturesare used to produce HMBM (180°C)due to the use of a harder bitumen type.These temperatures ensure that the aggregateis dry, the asphalt binder adequately coatsthe aggregate, and the mixturehas a suitable workability (so that it can bestored in silos, transported, spread,and compacted) . WMA technologyis now available to decrease the productiontemperatures of the bituminous mixtures,by reducing the shear resistance of the mixtureat construction temperatureswhile reportedly maintaining or improvingpavement performance.In the present study, the potentialof one WMA technique is analysed,comprising the modification of the binderwith a wax additive. The objective of this studywas to assess whether it would be possibleto use this additive in order to produceboth HMBM and HFBM mixtures by usingbase bitumens softer than those normally appliedin such mixtures, i.e. 35/50 wax modifiedbinder vs. 10/20 pen bitumen (HMBM),and 160/220 wax modified bindervs. 50170 pen bitumen (HFBM).The results obtained in the bindercharacterization tests allowed selecting~ european roads review 18 • Spring 201 1 • RGRA


the optimum additive contentand the WMA temperature reduction.Then, performance tests (water sensitivity,wheel tracking tests, stiffness and fatigue tests)were carried out on the conventional and waxmodified WMA mixtures, thus beingpossible to obtain the main conclusionsabout the use of these new WMA mixtures.Literature reviewon WMA mixturesA number of new processes and productsare available to reduce the temperatureat which the bituminous mixtures are mixedand compacted, apparently without compromisingthe performance of the pavement.These include the useof various physical-chemical means,e.g. waxes and surfactants [1 , 2].two phase bitumen introductionin the mixtures [3]. foamed bitumens [4Jor emulsions [5J . These technologiesare usually classified as WMA mixtureswhen produced slightly above 100 0 (and as half-WMA when mixtures are producedslightly below that temperature [6J.These new products can reduce productiontemperatures by as much as 40 percent [7J.Reducing the production and applicationtemperatures will provide several benefits,including reduced emissions, fumes (Photo 1),and odours, a cooler work environment,and evident energy savings [8J .However, it is essential that the overallperformance ofWMA is truly as good as HMA.On a life-cycle basis, if a WMA does not performas well as a HMA, there will not belong term environmental benefitsor energy savings. Thus, several authorshave been studying WMA additives,binders and mixtures [8, 9, 10].in order to improve their performance.The WMA technology used in this studywas the addition of a specific wax additive,Sasobit® (Photo 2) to the asphalt binder.Sasobit® is a Fischer-Tropsch (F-T) or synthetic waxthat is created during the coal gasification processand that has been used as a compaction aidand a temperature reducer. The Sasobit®process incorporates a low melting pointorganic additive that chemically changesthe temperature-viscosity curve of the binder [9J.This additive melts at approximately 100 0 (and significantly reduces the viscosityof the base bitumen. It increases the asphaltresistance to deformation throughoutthe operating temperature range without affectingthe low temperature properties of the mixture,which are determined by the characteristicsof the base bitumen [11 J. Sasobit® is completelysoluble in bitumen at temperatures above 115°C.It forms a homogeneous solution with the basebitumen on stirring reducing remarkablyits viscosity. This also enables mixingand reducing by 10-30 0 ( the handlingtemperatures of the asphalt [11 J.The influence of Sasobit® in the DSR rheologicalproperties of a 50/70 pen bitumen (Figure 1)was assessed in a previous study [10J. »>b)Photo 1Fumes observedat the dischargeof the HMA (a)andWMA(b)mixturesfor the trucks.I.:>lE+04- ... 850/70 + 4% Sasobi~Figure 1Influence ofthe Sasobit®content inthe DSR rheologicalpropertiesof a 50/70 penbinder 1101~::J~"to0:.>


An evaluation of unusual Warm Mix Asphaltsproduced with wax additivesIt was observed that Sasobit® isessentially an elastic material below its meltingpoint (102°C), and it increases the complex modulusat operating temperatures (25 to 80°C),in direct proportion to the amountof additive used. The reductionof the complex modulus at applicationtemperatures (above 120°C) is a central objectiveof this type of WMA additives, but only a minordecrease is obtained by comparing bitumensbefore and after wax modification.Thus, higher quantities of Sasobit® should be usedin order to ensure a major decreaseof the complex modulus, maximizing the decreaseof WMA application temperatures [10J .According to [12]. Sasobit® has shownto improve the compactability of mixturesin both the shear gyratory compactorand vibratory compactor. Statistics indicatedan overall reduction in air voids.Improved compaction was notedat temperatures as low as 88°e.This additive does not increasethe rutting potential of asphalt mixtures.Properties of the pure bitumensand wax modified bindersGeneral propertiesIn order to classify the binders used in this study,a basic characterisation was performedin accordance with the EN 12591 standard.This included penetration tests at 25°C(following the EN 1426 standard) and softeningpoint tests (also known as R&B temperature,according to the EN 1427 standard).These tests were also used to comparethe basic characteristics of the pure bitumens(HMBM - 10/20; HFBM - 50nO)with those of the wax modified bindersin order to select the optimum additive content.The samples of modified binders were obtained bymixing the bitumen (HMBM - 35/50;HFBM -160/220) with the additive for a periodof five minutes at a temperature of 130°e.These samples comprised the additionof three percentages of paraffin wax additives(2, 4 and 6%) to each base bitumen usedin both studies. The basic properties obtainedfor the paving grade bitumensand for those obtained by the additionof a certain amount of wax are summarized in Table 1.It was observed that the higher the quantityof wax additive used to modify the bitumen 35/50,the closer its penetration grade becomes to the oneof binder 10/20. However, it was not possibleto obtain the same penetration of bitumen 10/20,even when using the highest additive contentof 6% with bitumen 35/50. Concerningthe softening point temperature, the additionof the wax wields a significant change in the binder,thus being possible to obtain the same R&Btemperature of binder 10/20 by modifyingthe bitumen 35/50 with only 2% of additive.Considering both results, the optimum additivecontent considered as "ideal" to continuethis study was 6%.The most significant changeswere observed in the HFBM case study,in which the paraffin wax extremely hardensthe very soft base bitumen 160/220.Case studyBitumenAmountof additivePen(dmm)~Pen ~Pen R&B ~R&B(dmm) (%) (OC) (0C)~R&B(%)10/20 0% 16.40% 37.9HMBM35/502% 25.74% 23.56% 21 .850/70 0% 53.50% 153.7HFBM160/2202% 96.04% 79.66% 70.20.0 0% 70 00.0 0% 52 012.2 32% 73 2114.4 38% 89 3716.1 42% 94 420.0 0% 50 00.0 0% 39 057.7 38% 52 1374.1 48% 80 4183.5 54% 92 530%0%40%71 %81 %0%0%33%105%136% 0Table 1Results obtained for the penetration at 25°C and softening point of the studied binders~ europeanroads review 1 B • Spring 2011 • RGRA


Thus, it was observed a great reductionof the penetration and a huge increaseof the R&B temperature just by using 2%of additive. However, it was necessaryto use the highest additive content (6%)in order to obtain a penetration grade nearerthe one of binder 50170, and so this is the optimumadditive content selected to continue this study.This additive content was also selectedsince it increased the softening point temperatureof the base bitumen by 53°C.Dynamic viscosityIn order to evaluate the propertiesof the several binders at higher temperatures(100 to 180°C) in which the bituminous mixturesare mixed and applied, their dynamic viscositywas accessed using a rotating spindle apparatus(according to the EN 13302 standard).The method used to evaluate the dynamic viscosityof the binders at different temperaturesis described in detail in [1 OJ. The evolutionof the viscosity of the studied bitumens(10/20 and 50170) and wax modified binders(35/50 and 160/220 with 6% of additive)with the temperature, can be observed in Figure 2.10Performance of the conventionaland wax modified HMBMand HFBM mixturesGeneral propertiesTwo different mixtures were used in this study,namely a high modulus bituminous mixtureAC 20 Base (HMBM), which should be usedin a base course, and a high flexibility bituminousmixture AC 14 Surf (HFBM) that should be usedin a surface course, both complying with the gradingrequirements for those types of mixtures.The mix design of the mixtures was carried outaccording to the Marshall Method, and the samebinder content (HMBM = 5.3%; HFBM = 5.0%),aggregate type (granite) and gradationwas used for both HMA and WMA mixes.After determining the amount of additiveand the mixing temperatures for the WMA mixtures,and based on the mix design carried outfor the HMA mixtures, the engineering propertiesof the final WMA mixtures were assessedthrough laboratorial testing in order to determinerelative measures of performance in comparisonwith the corresponding HMA mixtures.- 50/70--- 160/220 + 6% additive- 10/2035150 + 6% additive- Equal viscosity 0.3 Pa.sFigure 2Dynamic viscosityof the studied binders120130 140 150 160 170Temperature (0C)180oIt was observed that the addition of waxesto softer base bitumen (in comparison tothe harder pure bitumen used in the HMA mixtures)is obviously the best solution to reducethe dynamic viscosity and the mixing temperatureof the WMA binders. The reductionof the WMA production temperaturewas assessed by comparing the temperaturesat the equal-viscosity value of 0.3 Pa.s:• the addition of 6% of wax additiveto the bitumen 160/200 (T = 120°C)allows reducing nearly 30°C in comparison withthe pure bitumen 50170 (T = 150°C);• the highest reduction of temperature(nearly 40°C) was obtainedwith the modified binder 35/50 with 6% wax(T = 140°C), if compared withthe pure bitumen 10/20 (T = 180°C).Water sensitivityThe mixtures were tested for water sensitivityaccording to the EN 12697-12 standard.This test comprises the assessmentof the indirect tensile strength (ITS),carried out according to EN 12697-23,of two identical groups of specimens conditionedin different environments (dry and wetwith the application of vacuum).The test procedure includes also the evaluationof the indirect tensile strength ratio (lTSR)between the average results of both groupsof specimens, in order to assess the watersensitivity of the mixture (Figure 3).»>europeanroads review 1 B • SpPlng 2011 • RGRA Ell


An evaluation of unusual Warm Mix Asphaltsproduced with wax additivesthe mean proportional rut depth (PRD AIR )and the mean rut depth (RD A1R ), in air.which are shown in Table 2.MixtureHFBM HMA HFBMWMA50/70 160/220 + 6% waxHMBM HMA10120HMBMWMA35/50+ 6% waxWTS A1R0.24 0.25(mm/10 3 cycles)0.060.07PRD A1R (%) 13.55 15.606.165.13RDAIR (mm) 5.70 6.592.602.160Table 2Permanent deformation parameters obtained by using the wheel-tracking test4,500 100%4,000 95%3,50090%~ 3,00085%:!!.2,500 ..VIVIt:::80% t:::2,0001,50075%1,000 70%500 65%0 60%HFBM HFBM HMBM HMBMHMA WMA HMA WMA 0Figure 3Water sensitivity results of the studied mixturesIt was observed that the use of the wax additivewith softer base bitumen slightly increasedthe ITSR of both mixtures (85 to 92%in the HMBM; 69 to 72 % in the HFBM),while the ITS has decreased 30 to 40%due to the use of the softer binder.Although the difference is not significant,it confirms that the influence of the basebitumen penetration in the water sensitivityis higher than that of the wax additive.Permanent deformation resistanceThe determination of the resistanceto permanent deformation was carried outusing the Wheel-Tracking Test, WTT(according to EN 12697-22 standard).The susceptibility of the WMA and HMA mixturesto deform was assessed by measuringthe rut depth formed by repeated wheel loadapplications at a temperature of 50°C.The average results of the WTT requiredon EN 12697-22 standard to rankthe performance of the studied mixturesare the mean wheel-tracking slope (WTS AIR ),One of the main advantages of the introductionof wax additives in bituminous mixturesis the reduction of their permanent deformationsusceptibility. This is clear in Table 2,where the performance of mixture HMBM WMAis similar or even better than that of mixtureHMBM HMA. As for HFBM HMA and HFBM WMAmixtures, the results are very close to each othereven though the base bitumen used in HFBMWMA mixture (160/220) is sign ificantly softerthan the one of HFBM HMA mixture (50170),which confirms the role of the wax additive.StiffnessThe stiffness modulus and phase anglewere obtained for the WMA and HMA mixturesby using the four-point bending beam test,with a repetitive sinusoidal loading configuration,as stated in the EN 12697-26 standard.The frequency sweep (0.1 to 10Hz) testswere carried out at 10, 20 and 30°(,thus being possible to draw the master curvesof the stiffness modulus, phase angle,storage and loss modulus of the studied mixtures,presented in Figure 4.It can be concluded that the wax additivehas a stiffening effect on the mixtures.However, since softer bindersare used, the effect of the additiveis not so significant, and thus the stiffnessmoduli of both WMAs were lower thanthose of the corresponding HMAs.Nevertheless, it can be observedthat the mixtures incorporatingthe wax additive have showna less viscous behaviour (lower loss modulus),and that the phase angle of such mixturesis less susceptible to the test frequencies,showing lower values for the lower frequenciesthan those of the HMAs.EJ:I europeanroads review 1 B • Spring 2011 • RGRA


14,000 --HF8M (HMA 50/70)---HF8M (WMA 160/220+wax)--HM8M (HMA10/20)- - - - HM8M (WMA 35/50+wax)Iii" 12,000....~ 10,000III..,'';::;--VI---01.E-03 1.E-01 1.E+01 1.E+03Frequency (Hz)"E:QIC.cQI '"III~.... '"70.060.050.040.030.0 --- .....,20.0, ..........,10.00.01.E-03 1.E-01 1.E+01 1.E+03Frequency (Hz)III 8,000:::J/..,""3 ,-6,000 ,-0,-E,-'-4,000----QIen /~ ..,"2,000.9VI01.E-03 1.E-01 1.E+01 1.E+03""-14,000Iii"~ 12,000::- 10,000w:::J"38,000,-./0 6,000,-'-E /IIIIII 4,000QI,,/'c:e 2,000--/Iii"....~NW..,III:::J"33,0002,5002,0001,5001,0000EIII 500III0.....01.E-03 1.E-01 1.E+01 1.E+03Frequency (Hz)Figure 4Master curves (stiffness modulus and phase angle) of the studied mixturesFrequency (Hz)oFatigue cracking resistanceThe fatigue cracking resistance of the mixtureswas obtained through four-point bendingtests (EN 12697-24 standard), carried outon strain control and with a repetitive sinusoidalloading configuration. Nine specimenswere tested at 20°(, for a frequency of 10Hzand at three different tensile strain levels.The number of cycles that correspondto a 50% reduction of the initial stiffness(failure criterion) was registeredas being the fatigue life of the specimen.Thus, it was possible to determine the fatigue linesof the different WMA and HMA mixturesunder study, which are presented in Figure 5.The fatigue cracking resistanceof HFBM HMA mixture is visibly lower(10 times inferior) than that of the other mixtures.The main reasons to justify these resultsare the use of a very soft bitumen (160/220)to produce the HFBM WMA mixtureand the specific mix design of both HMBMmixtures, which have a higher binder content.500- HFIM(HMASOI70)--- HFaM (WMA 1601220 + 6'111 additive)- HMBM (HMA10120)- - HMBM (WMAlSISO + 6% Mlditi'le)1.0E+041.0E+05Number of cyclesHfBMWMAy . 2969.8x "·R 0.91251.0E+06kMBMttMAy _ 15724, ·'$4II I. OMSlFigure 5Four point bendingfatigue test resultsof the studiedmixturesHMIMWMAUSI5.It 096111.0E+07o»>europeanroads re v iew 1 B • Spring 2011 • RGRA ED


An evaluation of unusual Warm Mix Asphaltsproduced with wax additivesThe fatigue resistance of both H M BM mixturesis similar, even if a slight decreasein the fatigue resistance of the HMBM WMAwas noticed. The HFBM WMA mixturewas clearly less susceptible to fatigue crackingthan the HFBM HMA mixture, namely due tothe use of a very soft base bitumenand the lower effect of aging in the WMA mixture,produced at lower temperatures.ConclusionsBased on the results presentedin this article and on their analysis,the following conclusions can be drawnfrom th is study:• the use of wax additivesin softer base bitumen isa very good solution to maximisethe reduction of the production temperaturesof WMA mixtures, allowing a reductionof 40 0 ( in the HMBM and 30 0 ( in the HFBM;• this particular additive significantly increasesthe permanent deformation resistanceof WMA mixtures, but barely changestheir water sensitivity;• the stiffening effect of the wax additives,between 10 and 30°(, is lower thanthe softening effect of the low penetrationbitumen used on the WMAs,and thus the stiffness moduli of both WMAswere lower than thoseof the corresponding HMAs;• the use of a very soft wax modified binderclearly increased the fatigue resistanceof the HFBM WMA, while the behaviourof both HMBMs (WMA and HMA) was similar . •111 Silva, H.M.R.D., J.R.M. Oliveira, UG. ferreira, P.A.A. Pereira 12010):Assessment of the Performance of Warm Mix Asphalts in Road Pavements.Int. Journal of Pavement Research and Technology, Vol. 3 (3), pp. 119-127121 Oliveira, J.R.M, Silva, H.M.R.D., Pereira, P.A.A., Matos, D.M. (2011):Combined Action of Waxes and Surfactants in WMA Mixtures, Proc. 5th Int.International Conference Bituminous Mixtures and Pavements, Thessaloniki,Greece131 EAPA (2005): Developments in Low Temperature Asphalt - EAPA PositionPaper, Brussels14] Jenkins, K.J. (2000): Mix Design Considerations for Cold and Half-WarmBituminous Mixes with Emphasis on foamed Bitumen, PhD Thesis, Universityof Stellenbosch, South AfricaIS] Prowell, B.D., Hurley, G.c., Crews, E. (2007): field Performance ofWarm Mix Asphalt at the NCATTest Track, TRR 1998, TRB, Washington, D.C.,pp 96·10216] Olard, f., Noan, C. (200B): Low Energy Asphalts, Routes Roads,n' 336/337, PIARC, pp 131-145171 Hurley, G.c., Prowell, B.D. (2006): Evaluation of Potential Processesfor Use in Warm Mix Asphalt, Journal of the AAPT. Vol. 75, pp 41-90181 D'Angelo, J., Harm, E., Bartoszek, J., Baumgardner, G., Corrigan,M., Cowsert, J., Harman, T., Jamshidi, M., Jones, w., Newcomb, D., Prowell,B., Sines, R., Yeaton, B. (2008): Warm-Mix Asphalt: European Practice,fHWA, AASHTO, NCHRp, Report fHWA PL-OB-007, Alexandria191 Button, J.w., Estakhri, c., Wimsatt, A. (2007): A Synthesis of Warm-MixAsphalt, Report 0-5597-1, Texas Transportation Institute, Texas110] Silva, H.M.D., Oliveira, J.R.M., ferreira, UG., Peralta, E.J. (2009):Evaluation of the rheological behaviour of warm mix asphalt (WMA)modified binders, Proc. 7th Int. RILEM Symp. ATCBM09, Rhodes, Greece1111 Sasol Wax GmbH (2004): The Bitumen Additive for Highly Stable EasilyCompactible Asphalts, Sasobit® Product Information 124, Sasol Wax GmbH,Hamburg1121 Hurley, G.c., Prowell, B.D. (2005): Evaluation of Sasobit® for usein Warm Mix Asphalt, National Center for Asphalt Technology, AuburnUniversity, Report 05-06, AuburnEB europeanroads review 1 B • Spring 20 1 1 • RGR A


AIPCRComite franc;ais~~ ......... ,.....,French CommitteePIARCcf-aipcr@ifsttar.frwww.cf-aipcr.orgWORLD ROADXXIV World Road CongressMexico, 26-30 September 2011Visit Pavilion FranceThe World Road Association (PIARC) brings together with international road community every 4 years.The 24th edition will be held at the Banamex Centre in Mexico on 26-30 September 2011.A congress and exhibit where are expected to attend:• More than 5, 000 decision-makers from 100 countries• 270 exhibitors at individual stands and national pavilions over an area of 12,000m2The French Committee of PIARC, www.cf-aipcr.org. seeks to bring together agents in the road and transport sectoron the 180m 2 of Pavilion France.Today, the following organisations have confirmed their attendance:ASCQUERASFACISMAColasConcept Travaux PublicsEgisFayatIDRRIMMEDDTLMichelinNorematRGRAUSIRFVectraSee you soon at Pavilion France!Contact and information:For CF-AIPCR, Evenements Pluriel - Marie-Helene Brunei - Ph. 09 65254809 / 060772 28 20HYPERLINK "mailto:pavillon-france_aipcr-mexico@orange.fr"pavilion-france aipcr-mexico@orangeJrThis statement has been given Ubifrance certification


Christophe NICOOEMEDirector GeneralEuropean Union Road Federation(ERF)------i Transport StrategiesThe European Commission WhitePaper on the Future of TransportThe point of view of the European Union RoadFederation (ERF)The road to the futureOn March 28, 2011, the European Commission(EC) released its White Paper on Transport, establishingthe future framework of the transport strategiesfor Europe in the future.In the principles the EC White Paper recognises theimportance of mobility and transport forthe European economy and society. It also underlinesthe requirement for sustainable transport inthe context of transport's oil dependence and thenecessity to drastically reduce the greenhousegas emissions (up to 60% by 2050 with respectto 1990).The White Paper acknowledges the role of newtechnologies for vehicle and traffic management as a key factor for lowering thetransport emissions in the European Union. In order to tackle these challenges, thetransport infrastructure needs to be improved for providing economic growth whileminimising the impact on the environment.Co-modalityThe White Paper also insists on the optimisationof the performance of multi modallogistic chains and the most efficientcombination of transport modes.It promotes the use of better modal choiceswhich will result from greater integrationof the modal networks: improved linkingbetween different modes of transportthrough multimodal connections should alsoenhance mobility.However, while preaching for co-modality,the EC's White Paper seeks to substantiallypromote rail and other modes of transportagainst road. According to its stated objectives,by 2050, it would like to see a 50% shiftin freight transport from road to railfor distances over 300 km and the majorityof medium-distance passenger transporttravelling rail. Moreover, and clearlywithout considering the severe economicimpact that it would haveon public finances, the Commissionwould like to triple high speed rail linesby 2050, while maintaining an overalldense rail network.Modern infrastructure.smart pricing and fundingThe ERF welcomes the Commission'sacknowledgment that infrastructure shapesmobility. It also supports the needfor sustainable financing methodsand, in this respect, agrees with the ideaof putting in place road pricing mechanisms,based on the user pays and polluterspay principle. However, it insiststhat such a pricing mechanism should berevenue neutral.ED europeanroads review 1 B • Spring 201 1 • RGRA


In land waterway 3.6".Rail 10.8%AJr O.1".Road 45.9%Air and Sea: only domestic and intra-EU-27 transport; provisional estimatesRoad: national and international haulage by vehicles registered in the Eu-27ffi7,000 -'-1--,--,---,--,---,--,--~-,--~-,--.,---,---6,000 -+!-+--I--+--t--t--+--+-+5,000 I I I ! ! , ! ! ! ! ! ! I:::: I I I I I I I I 11 I I 12,000 I I I I I I I I I I I I I1,000 I I I I I I I I I I I I I...00 1 1 1 1 1 1 1 1 1 1 1 1 1No o o o'"~ '"oNoN'" g-- co, emission· from transport in EU·27 (million tonnes)- Freight Transport in EU·27 (billion tkm)Passenger Transport in EU·27 (billion pkm)N..oN'"oN


Transport StrategiesThe European Commission White Paperon the Future of TransportFair and equal competition?The EC considers that road pricingand the removal of distortions in taxationcan assist in encouraging the use of publictransport. However, when we considerthe current situation, the road sectoralready provides a huge financialcontribution to the community (taxes, tolls ... )compared to other transport modes,while the public investments for the roadinfrastructure are continuously decreasing.The ERF again would like to pressfor an equal treatment with respect totransport pricing for all modes.The White Paper states that 'the costsof transport should be reflectedin its price in an undistorted way'.It also pleads for 'the eliminationof tax distortions and unjustified subsidies',and for a 'free and undistorted competition ...to align market choices with sustainability needs'.This principle, however, does not seemto apply to the generous public subsidiescurrently enjoyed by the rail sector,which is the biggest impediment to establishinga level-playing field between modes.The role of Intelligent TransportSystem (ITS)The ERF supports the White Paper'sacknowledgment of the importanceof deploying ITS as a means of ensuringa safer and more secure road transport systemand wishes to underline the needfor EU-wide interoperable systems for,amongst others, the following applications:road pricing, dangerous goods management,intelligent traffic management, secure parkingand road safety.Road SafetyThe ERF welcomes the White Paper's focuson vulnerable road users and ageing populationin line with the guidelines establishedby the 4th European Road Safety ActionProgramme, highlighting the roleof infrastructure as one the main pillarsto improve the safety record of road transport.It also acknowledges the highlighton a comprehensive strategyof action on road injuries and emergencyservices, including 'common definitionsand standard classifications of injuriesand fatalities, in view of adoptingan injuries reduction target'.ConclusionIn summary, the ERF welcomesmost of the principles behind the White Paperfor Transport, but also expresses its disappointmentabout many of its future objectives,especially regarding the unbalanced approachof the road transport compared withother transport modes, rail in particular,and pleads for a fair and equal treatmentof all transport modes.The ERF will continue monitoringthe future progresses and developmentsof the EC strategy in terms of transportand mobility . •Modern InfrastructureReference• ERf's Position Paper on White Paper: http://www.erf.be/• White Paper and 4th Road Safety Action Programme :http://eurlex.europa.eu/. http://ec.europa.eultransportlroad_safety/ED europeanroads review 18 • Spring 2011 • R GRA


Theresa ROMEllSenior Transportation PlannerMetropolitan TransportationCommission (MTC)(USA)Sui G TANProgram ManagerStreet Saver pavementmanagement softwareMetropolitan TransportationCommission (MTC)(USA)- --/ Preventive maintenanceRegional Asset Management Effortsand a Performance-based Approach toLocal Streets and Roads Funding AllocationGolden Gate BridgeOften when allocating funds to local agencies forstreet maintenance and rehabilitation, a metropolitanplanning agency (MPO) will employ a"fix-the-worst-street-first" approach or will allocatefunds based solely on which agency has theworst roads and thereby the greatest financialneed. If alternatively, an asset managementapproach can be adopted, the cost savings forthe region can be substantial. The objective ofthis article is to describe how the MetropolitanTransportation Commission (MTC) - the regionalplanning, programming and finance agencyfor the nine-county San Francisco Bay Area -successfully uses asset management at the regional level and includes preventivemaintenance practices as a performance measure for allocating federal funds tolocal agencies.Defining the ProblemMTC, recognizing the need to better documentthe regional, longer term needs of the local streetand road network, developed a network levelpavement management system in the mid-1980s.Its primary purpose was to documentthe aggregate need for local streetsand roads repairs, match this needagainst estimated revenues, and determinefunding shortfalls and their impacts.All 109 San Francisco Bay Arealocal jurisdictions plus 250+ jurisdictionsoutside of the region utilize MTC's pavementmanagement software, StreetSaver®.StreetSaver® uses a pavement conditionindex (PCi) that ranks pavement conditionson a 0 - 100 scale. The software allowsjurisdictions to inventory their street network,determine the maintenance needsof that network, and devise maintenanceprograms based on available revenuesand recommendations made by the software.Jurisdictions are required to submita copy of their StreetSaver® software databaseto MTC on a bi-ennial basis in order tobe certified to receive federal funding.This information allows MTC to documentboth the conditions and maintenance needsfor the entire region.Decades of neglect have led to the significantdeterioration of the San Francisco Bay Area 'sroadways. Insufficient maintenance fundingat all levels of government, has createdlarge shortfalls in a majority of jurisdictionswhere the cost of needed maintenancefar exceeds available funds.A comprehensive maintenance needs analysiscompleted in 2007 determined that the amountof funding requ ired to bring the region'slocal street and road networkup to an acceptable condition and maintain itthat way is approximately $34 billionover the next 25 years. The revenues that areprojected to be available to meet that need areonly $16 billion, leaving a funding shortfall »>europeanrosds review 1 B • Spring 2011 • RGRA ED


Regional Asset Management Effortsand a Performance-based Approachto local Streets and Roads Funding AllocationS25.0$20.0~~ S15.0iiie.E S10.0i:5.!!!IIIS5.0S-2007of approximately $18 billion.Further, these funding shortfalls, if not met,will increase by billions more as a resultof the cost of deferring needed maintenance.Figure 1 illustrates how pavementconditions in the Bay Area are projectedto decline over time and how the maintenancebacklog is expected to increaseunder the existing (current course) fundingscenarios. Just to maintain existing conditionsover the next 25 years (status quo),spending on street and road maintenancewill need to increase by nearly 70 percent.To improve conditions to a reasonable targetand reduce the maintenance backlog,a maintenance investmentof more than double the existing spendingwill be required.Figure 1Regional Pavement Maintenance Backlog and PCI over Time& Under Different Annual Funding Scenarios (In Constant 2006 Dollars)sm2012 2017 2022 2027 2032YearCurrent C"""" Status Quo Goal(52~Million.lYoar) (5343 MillionlYea


The basic method for measuring preventivemaintenance performance is to determinethe ratio between the percent of totalmaintenance budget a jurisdictionactually spends on preventive maintenanceversus how much is recommendedthey spend according to their pavementmanagement software.Because the recommended percentof budget comes directly from eachjurisdiction's pavement managementdatabase, it will vary depending onindividual network characteristics. Jurisdictionswith very a high network PCI will havea higher percent of budget recommendationfor preventive maintenanceand those with a very low PCI will havea lower percent of budget recommendation.Since the recommended amount of preventivemaintenance is expressed as a percentage,jurisdictions are not rewarded or penalizedbased on the size of their jurisdictions,the current condition of their pavementsor the size of their maintenance budgets.PotholeAs shown in Table 1, the recommended percentof budget for preventive maintenancefigure is generated by each jurisdiction'spavement management systemonce an "unconstrained budget needs"(needs are not constrained to available funds)model is run .»>Calculating Performance ScoresMTC has always defined preventive maintenanceas any maintenance treatment appliedto a street that has a PCI of 70 or above.Research has shown that the life extension valueof lower cost maintenance treatmentsis greatest while the pavement isstill in good condition. While it can begenerally said that any pavement with a PCIof 70 or above is in "good" conditionand will respond well to preventive maintenance,there is a gray area for some roadwayswithin the 60 to 70 PCI range,as to whether or not they can also garnerthe same life extension from lower costtreatments as those that are above 70.This is especially true in the caseof residential streets and low traffic rural roadwaysthat suffer mainly from" non-load"related distresses. For this reason, jurisdictionswere allowed preventive maintenance "credit"for treatments applied to arterialand collector roadways with a PCI of 70or above, and residential/local roadwayswith a PCI of 60 and above.Needs - Projected PCI/Cost SummaryYearPCITreatedPCIUntreated2009 85 742010 85 722011 86 712012 85 692013 85 682014 86 662015 85 642016 87 632017 86 61Cost$4,277,053$1,209,706$1,012,909$539,588$666,291$940,687$447,497$1,011 ,878$277,5852018 85 59$183,698PM Cost $2,744,440 Total Cost $10,566,893e M2~MTC StreetSaver®Table 110-Year Needs Analysis with Preventive Maintenance Recommendation0europeanroads review 1 B • Spring 2011 • RGRA ED


Regional Asset Management Effortsand a Performance-based Approachto Local Streets and Roads Funding AllocationData on actual preventivemaintenance applied is extracteddirectly from each jurisdiction's pavementmanagement database. From the databases,typically the most recent two years' worthof maintenance history can be examinedto determine what percentageof total maintenanceexpense was for maintenance on streetswith qualifying PCls (arterialsand collectors with a PCI of 70+and residential/local streets with PCls of 60+).Table 2 illustrates the summaryperformance score calculationsfor three Bay Area jurisdictions.ConclusionAs long as MPOs recognize maintenanceof the existing street and road networkas a regional priority, they should striveto ensure that existing resourcesare utilized in the most effective manner,and work to provide sufficient fundingto maintain the public's investment.M POs should ensure that the existingtransportation infrastructure -specifically the local street and road network -is managed to meet both currentand future demands and that expendituresof existing resources or optimized.JurisdictionRecommended percent PM 16%County of NapaAmerican Canyon43% 20%CalistogaActual PM Arterials & Collector $71,304 $486,373 $187,729Actual PM Residential - $1,010,649 $98,813Actual Total PM $71 ,304 $1,497,022 $286,542Actual Total Maintenance $14,657,343 $4,953,711 $1 ,776,620Actual percent PM 0%-Performance Score 3%Table 2Sample of Individual Jurisdiction Performance ScoresThe performance score,together with other factors such as jurisdictionpopulation, mileage and funding need,are combined in a formula that servesas the basis for the allocationof regional funding. Jurisdictions' performancescores are weighted based onthe jurisdictions's size, and affects 25%of their total funding.30% 16%o- f-'-----70% 81%Asset management principles can be appliedto achieve more effective decision-makingat all levels of government.The MPO role in a successful assetmanagement program includes supportingdata collection, condition and fundingneeds analyses, and integrating performancemeasures into funding policiesin order to make progresstowards regional targets . •um:I europeanroads review 1 B • Spring 2011 • RGRA


**.• ** *The Voice of the European Road


Etienne Ie BOUTElllERExecutive DirectorInternational BitumenEmulsion Federation (lBEF)Jean-Claude ROFF~PresidentSection des fabricantsd'emulsion routiere de bitume (SFERB) -­(USIRF Routes de France)'----l Bitumen Emulsion ProductionBitumen Emulsion in 2010:a watershed yearIn-place cold recycling RD 119 Ariege Department (France)The International Bitumen Emulsion Federation(lBEF) is the union of national associationsrepresenting the bitumen emulsion industryof 19 countries and more than 70% of worldproduction.Last October during its 5th congress, held alongwith the World of Emulsions (WOE 2010), some250 delegates from 30 countries were broughttogether, This event focused on the advancesand outlook for industrial firms and their clients.It also served as a reminder that the preservationof our road heritage is a collective commitment.Communication, education and trainingare also challenges that the industry must meet.As regards production, the industry is doing quite well with its output of8 million metric tons per year, stable over the last 4 years despite the crisis, withan additional potential of 3 million metric tons in Australasia. Furthermore, thepresent context is marked by two breaks whose conjunction is favourable forbitumen emulsions: the economic crisis and the resulting reduction in maintenancebudgets as well as increasing environmental requirements, These weightylong-term trends will contribute to the growth of applications for bitumenemulsion processes.The industry as well as all the parties concerned are well aware of the significantstakes involved and have forged many initiatives, This is attested to by the FirstInternational Conference on Pavement Preservation (Los Angeles 2010), theEmulsion Task Force in the United States, as well as the organisation of the InternationalSymposium on Asphalt Emulsion Technology (Washington October 2012).Transparent and validated tools are moreover available in order to quantify thespecific advantages of solutions provided by bitumen emulsions, in particularrelative to the reduction of greenhouse gas emissions (GGEs) and energy saving.liD europeanroads review 1 S • Spring 2011 • RGRA


IBEF: raising global awarenessand recognitionSince it was founded in 1995, the InternationalBitumen Emulsion Federation has ceaselesslyendeavored to serve its members. In addition tothe six original founding-father associations,IBEF now boasts members from 19 countries(1),who together represent more than 70%of the total emulsion production in the world.This as-yet-incomplete performance reflectstwo issues: first, the need to combine the energyand efforts of each association on a global scale,and second, the recognition of IBEF's roleas the representative of an industrythat is aware of the major role it will have toplay in the years to come.IBEF continues to act on an international levelto reinforce its existing network and expandits role, notably with new big playerssuch as Brazil, China and Russia.Life at IBEF revolves around meetings, symposiums,and conventions that it organizes or supports,in particular events on a national scalesuch as Asphaltica in Italy and the Mexican AsphaltCongress and an international scalesuch as the International Symposiumon Asphalt Emulsion Technology, ISAET(2).The World of Emulsions, one of IBEF's flagshipevents that gathers bitumen emulsion industrialists,is organized every four years hand in handwith the SFERB. The 5th WOE was held in Lyon,France, just prior to the 5th World Congresson Emulsion.WOE 2010: a communityof common interests• Global statistics• The future of bitumen• The future of emulsifiers• Sustainable development• Emulsion-basedasphalt concrete• Special techniques• Education and training• Standards• MarketingJohn KeayesNasreen TaskerChristian DepreeuwAzeem RemtullaMaria del Mar ColasVictoriaKobus LouwMark Mac ColloughBernard EckmannJorge Cardenas GarciaThese presentations are of course now availableto the industrial community, and beyond(3).To conclude this event, the President of the IBEFreminded attendees that pavement preservationon our streets and our roads is each person'sresponsibility, and bitumen emulsionshave a major role to play in this field.In addition, education and training were targetedas high priority issues. IBEF, in terms ofcommunication, is determined to work in houseand externally, to benefit all stakeholders.Global marketsTo perform well in a constantly changing environment,the industry must never stop evaluating its marketsand assessing what impacts them the most,both in the short and medium-term. Since 2008,the world has been going through an intenseeconomic crisis that has affected every sectorof business, a hostile environment that makesit crucial to know one's market inside out.REAL (UK)ARGUS (U.S.A)APAG (Europe)AAPA (Australia)ATEB (Spain)SABITA(South Africa)AEMA (U.S.A.)SFERB (France)AMAAC (Mexico)250 delegates from 30 countries and 5 continentsattended this event, which covered themesthat focused on users and customerswith a view on developing uses for bitumenemulsion. The one-day meeting was scheduledto allow for time for exchangesbetween the specialists in attendance,as a useful addition to informationprovided during the presentation.The presentations were deliveredby representatives of IBEF membersin national associations.Two scientific and prospective speechesfocusing on emulsifiers and bitumenwere given by renowned specialists.(Ii Australia, Bulgaria, Canada, France, Germany, India, Italy,Japan, Korea, Mexico, Morocco, Netherlands, Norway,South Africa, Spain, Thailand, Turkey, United Kingdom, U.S.A(2i ISAET - Oct. 9-12, 2012 - Hyatt Crystal City- Crystal City.VirginiaTo do so, at the end of 2009, IBEF launcheda global survey on the production of road bitumenemulsions amongst its membersand all related industries (emulsion producers,oil companies, emulsifier manufacturers).The survey's findings include datafrom over 100 countries around the world. » >(3i www.ibef.neteuropeanroads review 1 B • Spring 2011 • RGRA liB


Bitumen EmulsionProductionBitumen Emulsion in 2010: a watershed yearThe quality of the information provided bythe surveys highlights a gap in the knowledgewe have of certain markets. They can be mature,developing, or even practically non-existent.However, the development potential for bitumenemulsions is high, as we will see hereunder.As far as road bitumen emulsions are concerned,we must first note that volumes were stablefrom 2005 to 2009, with annual production figurestotal ing roughly 8 million tons (Figure 1).The same is true for road bitumen,with annual production of some 90 million tons.As was the case in 2005, the world's three leadingemulsion producers are the United States,France and Mexico. In 2009, BRIC countries(Brazil, Russia, India, China) arenow part of the top ten global producers.When one compares emulsion volumesand bitumen volumes, the figure 2 shows a ratioof 9.1 %. In greater detail, the ratio ishigher than 10% in Europe and in America,while it stagnates at around 5% in Asia.Of course, the apparent stability of these figuresis just an illusion. From 2005 to 2009,we observe a shift of bitumen volumesfrom industrialized countries and Latin Americato emerging countries, in particular in Asia(Figures 3, 4). For emulsions (Figures 5, 6),the shift is slighter, proof that the industryhas remained dynamic and that the qualityof emulsion-based techniqueshas helped boost the market in difficult times.224,000 192,000Emuslion vis Bitumen14.0%..,--------------.... ""'-Figure 1Emulsions:10 leadingproducers• USA• France• MexicoBrazil• China• Russia• SpainCanadaIndia• Japan~!!!12.0%10.0%8.0%6.0%4.0%2.0%0.0%Europe AfricaFigure 2Emulsion/bitumen ratioAsia OceaniaAmerica. 2005. 2009Europe•Africa•Asia Oceania• EuropeAfrica• Asia OceaniaFigure 3Bitumen 2005Figure 5Emulsions 2005• America• EuropeAfrica• Asia Oceania• Americaw!!!• AmericaCD Bitumen 2009il; Figure 4• EuropeAfrica• Asia Oceania• Americaw Figure 6.. Emulsions 2009liD european roads review 1 B • Spring 2011 • RGRA


The damage observed on some roads, includinghighways, helped raise awareness amongst usersas to the importance of preventive maintenance,thus reaching an audience above and beyondindustry professionals and network managers.Sustainable development:a new orderSustainable development can be definedin many different ways. Above and beyondthe most well-known environmental issues,it covers three different fields: Environment,Economics, and Society as Mr. Rt Hon PhilipHammond, Secretary of State for Transport,said during a speech he deliveredin September 2010(4) : "f. .. J the Coalition Governmentis committed to the sustainability agendain everything it does, including transport. [ ... Jwe are all too conscious of the fact thatsustainability means so much more than simply"carbon reducing". Sustainable solutions have,of course, first and foremost to be environmentallysustainable. But they must also be fiscallyand economically sustainable - affordable tothe taxpayer in the long-term and compatible withan economic growth agenda. And they must besocially sustainable as well - promoting socialmobility and recognizing the aspirationsof the least-advantaged in our societyand of the billions of people trying to improvetheir quality of life in the less-developednations of the world".The concept of sustainable developmentmust be understood in light of economic,environmental and social issues, with an obligationof global - thus unavoidable - coherence.EconomicsThe most accessible issue is of coursethe economic factor, but this must be understoodwith the long-term in mind. As far as roadinfrastructure is concerned, the idea is to preservethe network because it is an asset that belongs toeveryone. In Europe, the harsh winterof 2009-2010 revealed a numberof discrepancies in road maintenance policies.(4) IBM START Conference: Business Summit 10 September 2010In the United States, the land of pragmatism,the Federal Highway Administration (FHWA),in the wake of strict budget cuts, launcheda genuine "think & action tank" called the EmulsionTask Force (ETF), designed to draft outperformance-based specifications for bitumen emulsion.Some twenty years after Strategic Highway ResearchProgramm (SHRP), which led to the Superpavesystem for hot mixes, the ETF has set the sametargets for bitumen emulsion. In addition, the ETF'soriginality, notoriety and validity lie in the factthat it pools the means and the actions of DOTs(Department of Transport), industry, research(in particular universities) and standards bodies(American Association of State Highwayand Transportation Officials, AASHTOand American Society for Testing and Materials, ASTM).The idea that road preservation is an absolute necessitywas also covered in a dedicated event,the 1 st International Conference on PavementPreservation, that was held in California in April 2010(5).In terms of development, a number of practicalaccomplishments can be put to the creditof emulsion-based techniques, e.g., a studyby the Ohio Department Of Transportationwhose findings showed that surface dressings couldhelp lengthen service life by 7 years depending onthe initial condition of the pavement(6). »>100tPCRPCR increasedue to treatment ......--... r-_-


Bitumen Emulsion in 2010: a watershed yearProductionIn Europe, road maintenance budgetshave also been hit hard by the economic crisisand ensuing budget restrictions, forcing networkmanagers to optimize the techniquesthey use. Europe has joined Americain its quest for" more for less" .This is also true in Italy, where the emulsion industryis back in the forefront, able to providethe best solutions to their customers.EnvironmentIn Ireland and the UK, where budget cutshave been even more drastic, emulsionindustrialists were quick to focus backon conventional markets, which, ironically,are reaping benefit from these tough times.In short, their extremely thorough workon improving the quality of surface dressingshas paid off. These efforts, which will be detailedlater on in this article, include a driveto promote modified binders, which allowsfor use on more heavily-trafficked sections.Maintenance (km)120,--------------------------------------------100 +-------------------------------80+-----604020o2008 2009 2010 2011 2012 2013• hot mix overlay • surface dressing and midro-surfacingFigure 8Yvelines department (France): part planned for very thin wearing course worksFrance is also rediscovering the virtues of surface dressingsand micro surfacing, whenever their use can help optimize maintenancebudgets (Figure 8). This is the case in the Yvelines departementwhere the choice was made to increase pavement maintenancewithout increasing the budget, thanks to emulsion-based techniques [1).Environmental issues are always at the heartof industry concerns, if only because of increasingregulatory pressure. As such, this is not a constraint,nor is it an opportunity - environmental protectionis simply a "must "."Environmental issues are becoming increasinglyhard to ignore these days. For many companies,it has become a license to operate.Those who don't consider the environmentalimpact of their operations will find themselvesat a disadvantage, not just becausetheir competitors are doing it,but also because the public demands it(7) ".The situation in the Yvelines departement mentionedabove is very interesting case as it isone of some 20 French departements to haverolled out a "Convention d'engagement volontaire,CEV" (8), or voluntary commitment agreement.Redeploying surface maintenance techniques foreconomic reasons is first and foremost a reflectionof the agreement between the Assembleedes Departements de France (ADF) with its partners.In the case in point, the use of bitumen emulsionshas helped reduce greenhouse gas emissions(GGEs),as well as fossil fuel consumption.Customers and industrialists are all workingto respond to the same sustainabledevelopment criteria by boostingthe share of emulsion-based techniquesin surface dressings as a substitutefor cut-back and fluxed bitumen.(7) Sustainable strategies: when it pays to be green.Renato Orsato. INSEAD 2009(8) Convention d'engagement volontaire signee Ie 25 mars 2009par Ie ministere de I'Ecologie, de l'Energie, du Developpementdurable et de l'Amenagement du Territoire, l'Assembleedes departements de France, la Federation nationaledes Travaux publics, Ie Syndicat professionnel des terrassiersde France, I'Union des syndicats de I'industrie routiere fran~aiseet Syntec-Ingenierieria europeanroads review 1 B • Spring 2011 • R G R A


70%60%50%40%30%20%10%0%90%In Ireland and the United Kingdom,where these techniques are widely used,surface dressings are all emulsion-based.Germany has seen the same progress, as is shownin the following diagrams (Figures 9,10).80%+------70% ,------.1i'1'60%+-----50%40%+-----30% t-=-c:---20%10%0%emulsionSurface dressings in Germanynon modifiedemulsion cutback cutbackSurface dressings in United Kingdomemulsion• 2001. 2010_________ . 2001_________ . 2010cutbackFigures 9 and 10Surface dressing techniques in Germany and the United Kingdomfrom 2001 t o 2010New software designed by the USIRFcalled SEVE


Bitumen Emulsion in 2010: a watershed yearProduction __ .JAt the 5th World Congress on Emulsion, an oilcompany which plays a major role in the emulsionindustry illustrated this issue with humor:• 1959: "Rock & Roll is dead"• 1991: "mobile phones are not for everyone"• 1996: "The internet is a fad; it will pass"• 2010: "Cold mix asphalt is just for lightlytrafficked roads"SocietyThe road industry has specific duties in terms ofhealth and safety, given that it performsmost of its work on jobsites in proximity tothe general public. This is a very important issueand must be taken into consideration.Changing regulations will naturally lead the industryto focus on solutions with the lowest impact,be it in terms of environment or safety.This is without a doubt one of biggest consequencesof REACH [4]. which requires several exposure scenariosto be evaluated, making manufacturers moreresponsible and helping users stay as safe as possible.Progress made in economic and environmental termsoften goes hand in hand with improved safety,as is the case for cut-backs and fluxed bitumen,which are progressively being replaced by emulsion,notably in surface dressings. The following advantagesare worthy of note(10) :• Reduced risk of burns,• No more corrosive additives on site,• No more potentially hazardous vapor (explosive),• No more exposure to vapors and fumes(also hazardous for environment).A recent fatality has raised the attentionon the risks associated with cutback bitumenand there is a slow acceptance of bitumenemulsion as the way to move forward".ConclusionsBitumen emulsion techniques are not new.Much progress has been made since these processesfirst saw the light of day in the 1920s and 1930s.Today, bitumen emulsion is enjoying growtharound the globe. Every major country is now usingbitumen emulsion on their road networks.However, there is still much room for progress,given the technical advantages that emulsiontechniques can provide.This being the case, the year 2010 was witnessto unprecedented mobilization within the bitumenemulsion industry, illustrated by its extensiveparticipation in the WOE 2010 despite a particularlyharsh environment of budget restrictions.The industry is aware of the specific issuesthat could clip its wings, but also knowsfull well what can favor its growth.Ironically, the economic crisis is what has sparkedgrowth for emulsion techniques, a combinationof factors that have inevitably led to growth.Today, financial constraints, environmental concernsand social issues all make up the exceptionalbackdrop against which emulsion is growing.This is why 2010 is a watershed year. The Americanswere right when they formed the Emulsion TaskForce. In Europe, it is standard EN 13808 [5]and ensuing factory production controlsthat have helped build up decision-makers' confidencein this long-proven but ever evolving technique.In terms of volume, it is important to notethat the construction of new infrastructurein emerging countries, notably China and India,will mechanically lead to maintenance needsin the future, in which emulsion-techniqueswill have a major role to play.Should the Asia - Australia zone simply alignwith the rest of the world's emulsion/bitumen ratios(12.4%), this will create additional needsfor 2.8 million tons . •Unfortunately, we sometimes only become aware ofdanger when it is too late, e.g., when a seriousaccident has occurred during the use of hazardoussolvents or flux, even in plants. A fatalitywas reported in New Zealand in 2009:"In New Zealand, cutback bitumenstill dominates the chip sealing market.(10) Peter Thompson & Dante Cremasco: Resealingwith bituminious emulsions in the A.C T. 2nd InternationalSprayed Sealing Conference - Sustaining sprayed sealingpractice, Melbourne, Australia 2010Bibliography11] M. Borraccino. D. Meheut. Entretien et gestion des voiries departementales.Les innovations du departement des Yvelines. Revue genera Iedes routes et des aerodromes (RGRA). n° 888. oelobre 2010. pp. 11-1612] Norme NF EN 15322 Bitumes et liants bitumineux - Cadrede specifications pour les liants bitumineux fluidifies et fluxes, mai 2010131 c. Leroy, H. Molieron, V. Grosshenny, S. Quint, D. Fallone, S. Krafft,M. Jakubowski, E. Brosselier, F. Verhee, P. Venambre, SEVE, Ie nouvel outil desentreprises routieres, Revue genera Ie des routes et des aerodromes (RGRA),n° 883, mars 2010, pp. 28-3314) Dossier La profession et la regie mentation REACH, Revue generaledes routes et des aerodromes (RGRA), n° 873, fevrier 200915) Norme EN 13808 Bitumes et liants bitumineux - Cadre de speCificationpour les emulsions cationiques de liants bitumineux, septembre 2005&I europeanroads review 1 B • Spring 2011 • RGRA


15 years after, the new editionof the SFERB "Livre Bordeaux"is on saleThe English version will be publishedon the occasion of the 4th InternationalSymposium on Asphalt Emulsion TechnologyWashington DC, September 2008.Written by experts from SFERB and publishedby RGRA, this new version incorporatesthe newest developments having occurredduring this IS-year period in the fieldsof physicochemical research, standards,HSE, manufacturing and applicationsof bitumen emulsions, including equipmentand on-site spraying, laying and mixing techniques.---------------------------------------ORDER FORMPayment requested upon receipt of the invoice.PLEASE .. .... copy/copiesof "Bitumen Emulsions"FRANCEUnit price (excl. VAT): €95+ 5,5% VAT+ carriageTOTAL € .= .. =="-'OTHER COUNTRIESUnit price :€95+ carriageTo be invoiced to:Full nameCompany .TitleAddressZIP codeCountryE-mail ...CityIDATE:I SIGNATURE--1


Cyril FABREHead of Airfield Pavement,Airport OperationsAIRBUS S.A.5, (France)ICAO-AOSWG-PSG ICCAIA(1)Representative(1) In1erna1ional Civil Avia1ionOrganization-Airport Operation& Services WorkingGroup-Pavement SubgroupInternational Coordina1ing Councilof Aerospace Industries AssociationsThe heavy-Weight Simulator, " The Turtle"Jean-Maurice BALAYSenior Research EngineerInstitutfran~aisdesscienceset technologies des transports,de I'amenagementet des reseaux(lFSTIAR)(France)Dominique GUEDONMetrology/DataacquisitionManagerLaboratoire regionaldes Ponts et chaussees (LRPC)(France)---; Airfield pavement regulationThe Airbus high tire pressuretest (HTPT)When the International Civil Aviation Organisation(lCAO) initiated the Aircraft ClassificationNumber/Pavement Classification Number (ACN/­PCN) system in 1978, they included a simplifiedmeans for airports to categorize their pavementas either rigid (Portland cement concrete) orflexible (bituminous asphalt) pavement, an indexof subgrade (natural soil) categories thatexpresses the bearing strength of the soil onwhich the pavement rests, and an allowable tirepressure.From the advent of this system, the tire pressureelement was only loosely defined, having noprescribed methodology. The dilemma that arefacing both airports and aircraft manufacturers is that commercial aircraft tire pres-sures (on the A340, 8747 and 777 families of aircraft, and the upcoming A350 and8787 families as well) have gradually increased across the categories referred to as"x" (maximum allowable tire pressure 1.5 MPa) and "Y"(1.0 MPa) in the currentcoding, and yet few, if any, pavement failures have been identified as having beencaused by higher tire pressures. This article describes a full-scale test programmecalled" High Tire Pressure Test (HTPT)" which was performed in the frame of theICAO-AOSW-PSG task for supporting a change of the current tire pressure limits code.IntroductionIn 1978, ICAO initiated the adoptionof a single means for airports to expressthe load bearing capacity of airfield pavement,and at the same time, created a meansby which the aircraft manufacturerscould indicate the pavement loading intensityof their aircraft. The method is now used worldwide,and is referred to as the ACN/PCN System.There are five attributes to the ACN/PCN system:pavement type, subgrade code,allowable tire pressure, the descriptionof the method by which the pavement ratingwas developed and numerical PCN(and ACN) value [1].BackgroundWith the continuous increase in air trafficover the past three decades, combined withdemand for higher aircraft payload and rangecapabilities, and at the same time recognizingthe need to develop eco-efficient aircraft,the aircraft manufacturers have had to designtheir new aircraft to comply with these additionalchallenges. As a direct consequence, aircraft sizeand weight have gradually increased.Among many aspects, the landing gearis one of the most fundamental aspects of aircraftdesign. This system and its integration processencompass mUlti-engineering disciplines,including cost and weight considerations.EI:I europeanroads review 1 B • Spring 2011 • RGRA


• • ~;, "~.Photo 1HTPT SimulatorConfigurationIt can represent between 6 and 12% of the aircraftempty weight. Aircraft manufacturersmust comply with and anticipate the payload-rangeincreases and, at the same time, reduce cruise fuelconsumption, CO 2, NOx and other gases emissionson the ground, and meet required noise regulations.Aircraft pavement loading is the resultof an optimization process, essentiallydriven by aircraft weight (itself driven by range),landing gear concepts and aircraft geometrywhich leads to higher wheel loads (hence ACNs)and tire inflation pressures at maximum rampweight for the required maximum range.The only other way to significantly improvepavement loading without increasing tire pressureis to distribute aircraft weight over additionalwheels, which could have a major impact on payloadcapability and block fuel.However, four additional wheels to a typical aircraftequipped with a 4-wheel main landing gear(by either replacing a 4-wheel solution by a 6-wheelor adding a belly gear) would have detrimentalimpacts at several levels: the noise impactwould increase in range from +0.2 to +0.4 EPN (dB)(Effective Perceived Noise -EPN),depending on gear geometry, and the dragduring approach would also be increased.With the most optimistic hypothesisand using aircraft manufacturer design standards,the 4-wheel solution is 800kg to 1,000kg lighterthan an equivalent 6-wheel design,which is equivalent to 10 passengers with bags.Ground manceuvring is improved with the 4-wheelsolution as well, requiring less pavement widthfor U-turns and the ability to manceuvreinto tight gates or narrow taxi-lanes.Lastly, the overall direct value(the actual operating cost to the airline - factoringin the cost of the operational interruptions)is about USD 1 million per aircraft life(100,000 flight hours).High Tire Pressure Test (HTPT)Test facilityThe experimental runwayA variety of seven typical flexible pavement testsections were designed in Toulouse-Blagnac airport(Figure 1) with the intent of exhibitingwhether the new proposed tire pressurelimit code letter X of 1.75MPa wasa reasonable upper limit for typical pavements,as replacement to the present value of 1.5MPa. »>SIruCtu .. A Sb'ucturaB Slructure C17 m)35 m17m)35m17m)I3.5 m10mstructureD SbVctureE s .......... F s""",,, G(7 m)35 m(7 m) 3.5m~ ~~ "#,,,y/YA '/7-'"y"y"y"y§'. '//, ,//"yf "yA ,#,,,y#'ff. ,#,,,y, '#' "y "y§'. '/7- 9' "y"y, ~ '/7- ,&,,,y,,y,,y,,y,17m)3.5m17m),//"yA'/7- '////U-; ~~~ ~0; ~: --;0/;:/ //~/;~ 0~~/; :///~~~ :/;0://// %~0;: :;':~l~;:r~)I:. )I:. I'i.J::i J>.Strudure A Structure B s""",,, C structureD SlruCIure E Struclure F s""", .. GO.06m SAC 1 O.06m SAC 1 O. 12m SAC 1 O.oem SAC 2 O.oem SAC 1 O.08mSAC 1 Qf. O.08rn SAC 3Figure 1Pavement test Item, longitudinal viewjq1:5I~


'Airfield pavementregulationThe Airbus high tire pressure test (HTPT)As tire pressure effect is expectedto be concentrated on top layers(namely surface and base courses),experimental pavements were designedby selecting a subbase layer with a high bearingcapacity in order to limit structural damagewhich could occur in the deepest layersunder high traffic level and heavy wheel loads.Parameters that varied from one sectionto another were thickness of asphalt concretesurface layer (from 6, 8 and 12cm),its performance towards rutting (mix composition)and surface treatment (grooving).Test sections were instrumented to follow upboth permanent and resilient deformationat different pavement depths (Figures 2).Vehicle simulator at Toulouse-Slagnac Airport facility(a)Figures 2(a) Typical instrumentation layout(b) longitudinal and transversal gauges in Sase asphalt concrete (SAC)The heavy traffic simulatorThe landing-gear used for the testshad been developed by Airbus for the previousPavement Experimental Programs (PEP) [2].The simulator was equipped withfour dual wheel modules (Figure 3).The distance between the two wheelsof a given module, and the distancebetween two different modules,was chosen as large as possible so thatthe wheels and gears interactionare minimized in the deepest layerof the pavement. This was done to studythe influence of each module and each wheelon the pavement independently.Figure 3Vehicle simulator, the "Turtle"The High Tire Pressure Test (HTPT) explored currentand forecasted aircraft wheel loads and correspondingtire pressure from low to high temperature conditions.Four loading cases were selected to compare wheel load(28.7 and 33.2t) and tire pressure effect (15 and17.5 bar) by combining both parameters (Table 1).B3 e ~ropean roBds rev ew 18 • Spring 2011 • RGRA


Table 1Vehicle simulatorloading casesModulePnz Load per wheel Deflection Gross contact areaBar PSI Tons Lbs mm cm 2Ml 17.5 254 28.7M2 15.0 218 33.2M3 17.5 254 33.2M4 15.0 218 28.763,270 99 1,60873,200 125 2,17173,200 112 1,86963,270 112 1,869~II!vTest CampaignThe test campaign consisted of runningthe loading simulator on the experimentalpavement at a low speed (Skm/h) which wasintended to be representative of the most damagingcase and was performed during a full yearin order to be representative of year-roundtemperatures, starting at low temperatures(in mid-September 2009) and finishingwith high temperatures (at the completionof the tests high surface temperaturesof approximately 60°C were recorded) .A specific lateral wandering was applied to avoidthe creation of gutters. Wander path was about1.6m and space between two adjacent trajectorieswas 400mm, corresponding to the tirecontact area width. Up to 11 ,000 passagesof the simulator were applied from October 2009to August 2010 (Figure 4).Results and analysisEach rutting survey consisted of 84 transversalprofiles measurements, distributedover the 7 structures and 4 twin-wheel modules(3 transversal profiles P1, P2 and P3for each of the 28 structure-module sets).Figures Sand 6 show two examplesof such transversal rutting profiles.IS10-25-10-35 +--_-___ ~-_--_-_--~-_-_--~o.s 1.5 2 2.5 3 '-' 4.5Transversal position (m)- 1,000 pas. - 2,000 pas. - 5,240 pas. - 7,000 pas. - 8,000 pas.- 9,000 pas. - 10,000 pas. - 10,500 pas. - 11 ,000 pas.25-C20· (15-(10· (s'cO'c~ ~ ~~ ~ ~0 0 0 0 0~ ~~~ ::> " ~CUfT\Utati'n traffic - AC mean tflnPerature12,00010,000• • 000•• 0004.0002.000i-!~~!~-;Figure 5Transversal rutting profiles measured on section B, profile P2, module M320,-------------------------,10Figure 4Evolution of the cumulative traffic and the temperature in AC-~~------~---------~------~0.51.5 2.5Transversal position (m)3.54.5- 1,000 pas.- 8.DOOpas.- 2,000 pas.9,000 pas.- 5.240 pas.- 10,000 pas.- 7.000 pas.- 10,500 pas.Figure 6Transversal rutting profiles measured on section G, profile P2. module M3Vehicle simulator - Rear viewFor all sections (A to G). rutting depthat 7,000 passes (mid April 2010)remains very low, due to the very moderateAsphalt Concrete (AC) temperatureuntil this date. Then the evolution curvesclearly exhibit a change in the slope,as a more and more significant percentageof the traffic is applied at AC temperaturesgreater than 30°e. »>europeanroads revIew 1 B • Spring 201 1 • RGRA I!EI


Airfield pavementregulationThe Airbus high tire pressure test (HTPT)Table 2 summarizes the maximum rut depthmeasurement at test completion . The wheel-loadeffect on rutting is assessed by comparing modulesM1 (28.7t) to M3 (33 .2t) both inflated at 1.75MPa.and modules M2 (33.2t) to M4 (28.7t)both inflated at 1.5MPa.Similarly. the tire pressure effect on rutting isassessed by comparing modules M1 (1 .75MPa)to M4 (1.5MPa) both loaded at 28.7t per wheel.and modules M2 (1 .5MPa) to M3 (1 .75MPa)both loaded at 33.2t per wheel.Tyre pressure effect must be consideredwith an associated wheel-load. both parametersbeing closely and intrinsically linked and cannot bedescribed as isolated parameters but contributionof each parameter to rut depth developmentcan be evaluated separately.Effect of surface AC thicknessDespite the three different thicknesses(6cm. 8cm. and 12cm) of the same standard surfaceAC used in structures A. B. C and E. their ruttingbehaviour is quite similar. This may be due to surfacerutting being caused by permanent deformationnot only of the surface AC but also the AC basecourse. which is identical in sections A. B. C and E.Rutting mechanismDevelopment of permanent deformations increased withhigh AC temperatures. The tests confirmed thatthe speed of the rutting evolution significantly increasedas the AC temperature exceeds the range 30-35°C.irrespective of the load and tyre pressure configuration .SectionModule M1 Module M2 Module M3(mm) (mm) (mm)Pressure effectModule M4 M3 vs M2 M1 vs M4 M3 vs M1(mm)@33.2t @28.7t @1.15MPa(~in mm) (~in mm) (~in mm)Wheel-load effectM2 vs M4@1 .5MPa(~in mm)A 24.9 22.9 27.921.8 5.0 3.1 3.01.1B - E 22.9 22.4 27.520.7 5.1 2.2 4.61.7C 24.2 22.6 25.421.8 2.8 2.4 1.20.8D 20.9 20.2 21.917.5 1.7 3.5 1.02.7F 19.7 21. 1 22.617.8 1.5 1.9 2.93.3G at10.000 passes23. 2 22.0 26.920.9 4.9 2.3 3.71.1G at10.500 passes34.1 33.5 44.732.5 11 .2 1.6 10.61.00Table 2Synthesis of the rutting depths reached at the end of the testsCombined results from the rutting measurementand core sampling led to the following observation:Effect of AC rutting performanceFor section D (high rutting performance AC).material behaviour with regard to ruttingis noticeably better than the other sectionsbehaviour. and tends to reduce wheel-loadand tire pressure effects. As expected.rut depth on section G (low rutting performancesurface AC) is higher than on other test sections.and visco-plastic creeping at constant volumestrain-path is more significant.Effect of surface treatmentSurprisingly. grooving (section F) appears toimprove the rutting behaviour compared to Band E (which have the same structure) to a similarextent as section D using high rutting performance.In addition. core samples show that the permanentdeformation not only affects the surface AC layeras anticipated. but also the whole thicknessof the surface and base AC. This permanentdeformation of the bituminous base layerand the unbounded materials is more representativeof parking area loaded by quasi-static loads.It is mainly considered as the consequenceof the very low moving speed of the simulatorduring the HTPT test.Wheel-load effectAt 1.75MPa inflation pressure. the weight increasefrom 28.7t to 33.2t leads to a growth in ruttingbetween + 1 mm (section D) and +4.6mm(section B-E) according to the pavement section.At 1.5MPa inflation pressure. the weight increasefrom 28.7t to 33.2t leads to a growth in ruttingbetween +O.8mm (section C) and +3.3mm(section F).BI europeanroads review 1 B • Spring 2011 • RGRA


As a result, the impact of wheel-load on ruttingdepth remains relatively moderate.This contradicts the approach for the ruttingevaluation derived from soil and bituminousmaterial damage laws including stressraised to positive power, which would givemuch greater differences in rutting.Tyre pressure effectAt a wheel-load of 33.2t, the tyre pressureincrease from 1.5 to 1.75MPa leads to a growthin rutting between + 1.5mm (section F)and +5.1 mm (section B-E).At a wheel-load of 28.7t, the tyre pressureincrease from 1.5 to 1.75MPa leads to a growthin rutting between + 1.9mm (section F)and +3.5mm (section D).Similarly to weight effect, the impactof tyre pressure on rutting can be considered asmarginal and considerably less importantthan it is often suspected to be.It should be observed that these major findingsof the HTPT are in good concordance withthe results of the similar tests performed bythe Federal Aviation Administration (FAA)and the Boeing Company at the Atlanctic Cityfacility [4] .ConclusionsThe primary objective of this full-scale testcampaign was to evaluate whetherthe new proposed tyre pressure upper limitof 1.75MPa for Code X of the ACN/PCNis reasonable for typical flexible pavement.This objective was successfully achieved,and led to the main conclusion that this proposalfor change is fully compliant with the test results.The experiment allowed additional lessonswhich could be of interest for further investigationon this topic.in the ACN calculation and the pavement thicknessdesign method as well.Rutting mechanismRutting initiation is more related tomean AC temperature than traffic levelor load parameters. Indeed, the ruttingappeared at the same time for all consideredwheel-loads or tyre pressures, and rut depthvariation increased simultaneouslywith temperature independentlyof tyre pressure. The prevailing ruttingmechanism is the post-compactionof the pavement material by trafficon both surface and base AC.The visco-thermoplastic creepingof AC material is secondary to the postcompaction except for the low ruttingperformance AC material which combinesequally both failure modes. The core drillingperformed after test completionshowed that approximately half of the totalrut depth is found on the unbounded materials.This unbounded material rutting ismore sensitive to the higher wheel-loadsconfirming the prevailing wheel-load effecton the deepest layers and thereforethe relative low tyre pressure effecton AC material.In light of the High Tyre Pressure Test campaign,it has been established and substantiatedthat an increase of tyre pressurefrom the current X category limit of 1.5MPato an upper limit of 1.75MPa will not adverselyaffect either surface and base AC materialsor the structural capacityof typical airfield pavement (i.e. pavementlife duration will not be decreasedas a consequence of increasing tyre pressure) . •Wheel-load and tyre pressure effectFor a given wheel-load applied onpavement at a very low speed,the full-scale test campaign showed that rutdepth differences under the different loadingcases ranged from 1.5mm to 5.1 mm,showing that the contribution of the tyre pressure(i.e. isolated from wheel-load effect)to rutting can be considered as marginaland acceptable for the majorityof pavement dedicated to heavy aircraft.Wheel-load effect affects both the surfaceand base AC, but more confined in unboundedmaterial, therefore more related tothe structural behaviour of airfield pavementwhich is already known and consideredReferences------[1 [ ICAO. 2004. Aerodromes. Volume I. Aerodrome Design and operations:The ACN/PCN method[2J C. Fabre, l.-M. Balay, A. Mazars, D. Guedon. ' Les programmesexperimentaux sur pistes Airbus A380 " Revue generale des routes et desaerodromes (RGRA) n0840, juin 2005. pp. 33-5313[ BOEING I FAA (NAPTF), Report on high tire pressure tests. Atlantic City.Nl, USA, 2006[4J FAA (NAPTF), Full-Scale High nre Pressure Tests on Heated Pavement.FAA Airport Technology Research and Development, William 1. HughesTechnical Center Atlantic Cityeuropeanroads 'evlew 1 B • Spr'lng 2011 • RGRA ED


Jean-Louis CU~NOUDTechnical ManagerCOLAS Suisse(Switzerland)VALORCOL: asphalt mixcomplying with environmentand sustainable developmentA day rarely goes by today without hearingabout global warming. Wasn't the 2006-2007winter the warmest ever recorded? And whatabout the weather enjoyed in Switzerlandbetween mid-January and mid-February?And yet, it was in 1992 at the United NationsConference on Environment and Developmentin Rio, almost 20 years ago, that universalawareness of the risks of degradation run bythe planet was already getting under way.Depletion of natural resources and climatechange are among the chief causes of thedegradation and disruption of our ecosystems.The main culprits are: industries, agriculture, transport.Although not on this list, road construction companies have already beendemonstrating for several years their awareness and concern regarding thepreservation of our environment and our natural resources.The Switzerland particularitiesTo these global problems must also be addedsuch national particularities as, in Switzerland,the possible lack of quality aggregatesin the medium term and the presenceon the market of very large amountsof recycled asphaltWhile the data on this subject are very difficultto obtain, we estimate that 2.5 million tonsof asphalt millings are used in the constructionmarket in Switzerland each year.This is a sizeable value, consideringthat it represents about 50% of the annualproduction of new asphalt mixes (Figure 1 l.It is explained mainly by the fact thatthe Swiss road network has been almost thoroughlycompleted and that the great majorityof roadworks are maintenance operationsinvolving either total or partial pavementdeconstruction in keeping with a directiveon the gainful use of wastefrom mineral worksites [1] which callsfor the sorting and reuse of asphalt mixes.Landfilland other uses800.000tpyFigure 1Asphalt circuit in Switzerland - 2005 data (Source: Ammann)~ europeanraads revew 1 B • Spring 201 1 • RGRA


In Switzerland, standard asphalt mixesare manufactured at temperatures of the orderof 150°C and the recycled asphalt aggregate (RA)content is limited according to the valuesappearing in Table 1 [2] .Figures 2 and 3 represent respectively for differenttypes of asphalt mixes, including Valorco/:• energy consumption per tonne of materials placed,• greenhouse gas emissions (GGEs)per tonne of materials placed. »>Asphalt mixes, permissible asphalt aggregate quantities depending on courses,sorts and types of asphalt mixesSorts and types of asphalt mix for coursesWearing coursesAsphalt mixes for wearing courses AC S, AC Hand AC MRAsphalt mixes for wearing courses AC Nand AC lBinding courses and high-modulus asphalt mixesAsphalt mixes for binding courses AC B,high-modulus asphalt mixes AC EMEAsphalt aggregate contentIncorporated cold Incorporated hot[Mass %JI0 0:5:15 :5:30:5:15 :5:30~Table 1Permissible %of asphaltaggregatesin asphalt mixmanufactureBase and waterproofrng courses for railway tracksAsphalt mixes for base cources AC T.asphalt mixes for waterproofing coursesf or railway tracks AC RailSubbasesAsphalt mixes for subbases AC FFrom this table, it is clearly understoodthat the simple use of hot-mix asphaltdoes not make it possible to consumethe RA available on the Swiss market.Valoreol solutionTo deal with the different issues mentioned above,Colas Suisse has developed cold-mix asphaltusing 100% asphalt aggregates: Valorcol.Manufacture at ambient temperature (Photo 1)allows the saving of energy and a significantreduction in greenhouse gas emissions (GGEs)while limiting risks to workers (burns).850800750700650E" ~~g~ 500>. 450e' 400.. 350~ ~~g20015015050o:5: 25 :5:60:5: 30 :5:70 ~«Energy consumption per tonne of materials placedConventional asphalt Conventional asphalt VALORCOLfor wearing course for base course• Placement _ Transport • Manufacture _ Aggregates _ BindersFigure 2Energy consumption in MJ per tonne of asphalt placed60555045~ 40~c 35030.~.E: 25.. 20~IS~10Greenhouse gas emission per tonne of materials placedConventional asphalt Conventional asphaltfor wearing course for base courseVALORCOLD Placement .Transport D Manufacture _ Aggregates • BindersPhoto 1Manufacture and placement of Valoreol at ambient temperatureFigure 3Greenhouse gas emission in kg per tonne of asphalt placedeuropeanroads review 1 B • Spring 2011 • RGRA E&


VAlORCOl: asphalt mix complying withenvironment and sustainable developmentIn both cases, the values appearing in these figuresinclude all the following operations:• manufacture of raw materials (aggregates,bitumen, etc.);• transport of raw materials from their respectiveproduction site to the production siteof the final mix (mixing plant);• manufacture of final mix (asphalt = BB);• transport of asphalt mix from mixing plantto worksite;• and finally, placement of asphalt mix (BB).Manufacture and placementCompared to standard (hot-mix) asphalt,the manufacture of Valoreol requiresa specific production unit suited toemulsion techniques (Photo 4).On the other hand, placement is carried outwith conventional equipment,such as a grader or paver-finisher (Photo 5).Compacting is handled mainly by heavyand pneumatic-tyred compactors (Photo 6).The exclusive use of asphalt aggregates,sorted and correctly prepared (Photos 2 and 3)while also contributing to energy savingand to the reduction of GGEs, in particularby requiring half as much binderthan a new asphalt mix, contributesmainly to the preservation of natural resources(aggregates and bitumen) and landfills,the latter being rare in Switzerland.Moreover, as there are more worksitesthan there are aggregate production sitesand landfills, the use of recycled asphaltalso contributes to the reduction of materialtransport requirements.Photo 5Application of Valoreol with conventional equipmentPhoto 2Recycled asphalt used in manufacture of Valoreol, raw, without prior treatmentPhoto 6Compacting of Valoreol with heavy pneumatic-tyred compactorsPhoto 3Recycled asphalt used in manufacture of Valoreol, after treatment(asphalt aggregates)Application thickness depends on the gradationof the RA used, but is generally between 4 and 10cm.Larger thicknesses are possible but there is a greatrisk of insufficient evenness after compactingowing to the degree of bulking of cold asphalt.~ europeanroads review 18 • Spring 2011 • RGRA


Swiss referencesTo date, over 30,000 tonnes of Valoreol have been applied in Switzerland since 2006.The main Valoreol projects are the following:• 2006 A 16, section 2, lot 2.055, worksite road of Bure Sud - base course as replacementfor a hot-mix asphalt ACT (Photo 7);• 2008 Exterior improvements for national highway maintenance centre of Bursins (A 1) -base course as replacement for hot-mix asphalt ACT (Photo 8);• 2008 A 16, section 2, lot 2.260, subbase of motorway section Sud Combe Nord - Neu Bois,as replacement for hot-mix asphalt ACF (Photo 9);• 2009 A 16, section 2, lot 2.270, subbase course of tunnel section of Neu Bois - Combe Baidire,as replacement for hot-mix asphalt ACF;• 2009 Works on cantonal road No. 1572 Soulcy-Lajoux (Jura) - base course as a variantfor subbase stabilisation (Photo 10);• 2009 Route du Valanvron at Chaux-de-Fonds - wearing course for existing pavementwithout preparatory works (Photo 11);.2010 RC 64 route de Lully (Geneva) - base course as replacement for hot-mix asphalt ACT.Photo 7Application of Valorcol in base course on work site roadof A16 Transjurane motorway, section 2, lot 2.250 - 2006Photo 8Use of Valorcol in base course for exterior worksfor national highway maintenance centre of Bursins(A 1 Lausanne - Geneva) - 2008Photo 9Application of Valorcol in subbase on routeof A 16 Transjurane motorway, section 2, lot 2.260 - 2008Photo 10Application of Valorcol in base course on RC 1572Saulcy-Lajoux in the Jura - 2009Photo 11Application of Valorcol in wearingcourse on Valanvron communalroad at Chaux·de·Fonds - 2009»>europeanroads review 1 B • Spring 2011 • RGRA ~


DevelopmentVALORCOL: asphalt mix complying withenvironment and sustainable developmentMechanical performanceAs laboratory tests are not the same, it isdifficult to draw a parallel between the performancelevels of hot-mix asphalt (bitumen)and those of cold-mix asphaltof the Valorcol type (emulsion).It may nevertheless be stated that:• Valorcal is not sensitive to rutting,because of its high residual void content(- 15 to 20%);• Valorcal is an excellent anti-cracking product(use of a 160/220 bitumen emulsion)On the other hand, considering phenomenarelated to the curing time of bitumenemulsion asphalt, Valorcol exhibitsearly-age resistance to low shearing forcesand to punching.Laydown period and fields of applicationThe curing of emulsion asphalt mixes(time required for complete breaking of emulsion)depends on weather conditions and in particularthe ambient temperature and traffic levels.The higher the ambient temperatureand the heavier the traffic,the shorter will be the asphalt curing time.As long as the curing of the asphalthas not been completed, the mix remainssensitive to punching and to tangential forces.Hence, the laydown period of Valorcalis limited to the mild season,generally from May to October. Depending onlocations (high altitude, for example),it may be advisable not to lay downsuch an asphalt after the monthof September, or even earlier.Given all these considerations, the main fieldsof application of Valorcal are the following:• Subbase courses of all types of pavements;• Base courses of pavementsfor light and medium traffic.Use of Valorcal as a base coursefor pavements handling heavy trafficis possible after an in-depth study;• Temporary wearing courses (worksite road, e.g.);• Wearing course of light traffic pavement.Use as a final wearing course without protection(for example with chippings or slurry surfacing)remains delicate and must becarefully studied beforehand.It is also to be noted that, unlike hot-mix asphalt,it is possible to apply Valorcal on degradedsubstrates (cracks, potholes, deformations)without prior works. A preliminary studyis however still obligatory.In closing, let us also mention that the Valorcalmix received awards twice in Switzerland,in 2006 receiving a certificate of excellencein connection with the eco-awareness awardsorganised jointly by the township of Lausanneand Beau-Rivage Palace (Photo 12)and in 2008 receiving the Geneva Statesustainable development award (Photo 13)....u:z...c::;en:zQuu=...= Do.Qlie_.._-~--------CERTIFICAO'EXCELLENCED€CERNE ACOLAS SUISSE SAA LAUSANNEau A SCUAIS UN DOSSIER PRt",:SENTANTl.fl PROJET INNOVANT, R£AusTE ET DE GRANOEET AYAHT ~ REl'EMJ l'ATTENTKJNru,Uf( lORS DE l"ATTR8JTlON OIJ ~ 2006Photo 12Certificate of excellence awarded in 2006to Valorcol asphalt mix by the township of lausannePrix cantonaldu developpement durable_.~-Photo 13Sustainable development prize awarded in 2008to the Valorcol asphalt mix by the State of GenevaRe e .nee[11 Directive for gainful use of mineral worksi1e waste - Swiss federal officefor the environment, OFEV[21 Standard SN 640431-1 b NA (Swiss national annex of EN 13108-1)• M. Rotat, Y. Morlot, A. Tamisier, M. Bailie, « Valoreol ESU, valorisationdes enduits superficiels des chaussees a faible trafic • - Revue generaledes routes et des aerodromes (RGRA) n'867, juin 2008, pp. 64-69•lIB europeanroads review 1 B • Spring 2011 • RGRA


Fran~oi s OLARDPatrick HUONStephane DUPRIETResearch CentreEiffage Travaux Publics(France)-----1Innovationfor Long-Life PavementsGB5®: Eco-Friendly Alternativeto EME2 for long-life& Cost-Effective Base CoursesAggregate packing concepts developed in thefield of high-performance cement concretes,initially by A. (aquot (1937) then by contem ­porary researchers since the 1970's, weretransposed to the field of asphalt concretes(A(s). These concepts, associated with the useof the gyratory compactor on aggregates only,enabled the development of a new laboratorydesign procedure of dense high -modulusasphalt concretes. These mixes are characterizedby great coarse aggregate interlock andno need for low penetration grade bitumens toobtain the EME2 specifications requirements,in particular the 14,000MPa stiffness modulus value at 15°C.Besides, the use of approximately 4% of Styrene-Butadiene-Styrene (SBS)co-polymer modified bitumen combined with such an optimized aggregatepacking leads to the design of the so-called GB5® material, showing excellentcompactability, very high stiffness modulus and above all high fatigue resistancein a single formulation, allowing for reduced pavement thickness and greaterlongevity.Laboratory assessment of such materials consisted in the evaluation of compactability,moisture resistance, rutting resistance at 60°(, complex stiffnessmodulus at 15°( and fatigue resistance at 10°C. Apart from these results, thearticle also addresses the successful application of th is new material on differentjob sites, located mainly on French high traffic highways.The article illustrates that the proposed innovative material may be potentiallyconsidered from now on as a relevant solution for sustainable long lifepavements that do not deteriorate structurally, needing only timely surfacemaintenance. »>europeanroads rev,ew 1 B • Spring 2011 • RGRA DII


~------~------------~Innovationfor long-Life PavementsGB5®: Eco-Friendly Alternative to EME2for long-Life & Cost-Effective Base CoursesIntroductionControlling the volumetrics of asphalt mixesis the first step of any mix design procedure.Apart from binder-related considerations,as the aggregate component representsabout 95% of the weight of an asphalt mix,predicting and controlling packing propertiesof aggregates is of prime importance.Aggregate packing is mainly influencedby five parameters [1 , 2, 3, 6, 7J:• Gradation (continuously-graded, gap-graded, etc.);• Shape (flat & elongated, cubical, round);• Surface micro-texture (smooth, rough);• Type & amount of compaction effort(static pressure, impact or shearing);• Layer thickness [8J.This so-called GB5® project mainly focusedon the first parameter (gradation) by optimizingthe combination of fine and coarse fractions,reSUlting in an interactive network of coarseparticles in the asphalt mix, providing indirectlythe strongest mix resistance [9, 10Jand in particular the highest mix modulus.In order to reduce interactions of intermediateparticles on the coarsest ones in the mix,it is crucial to limit both their size and amountand fill air voids by a higher fraction of fines instead.On top of it, it appears that if the ratiobetween successive sizes in a skip gradationis chosen so as to give the most drastic reductionin voids, that reduction would be equal to,or possibly greater than, the most drasticreduction in voids for a continuous gradation.(a)Apart from the previous gradation-relatedconsiderations, the ability of SBS polymerto reduce fatigue cracking and agingis well recognized [11, 12J but the high modulusrequired for perpetual pavement base structuresusually calls for hard binders(and thus slightly higher binder contentto preserve fatigue resistance), having viscosityand compatibility issues with conventional SBS.Therefore, at Eiffage Travaux Publicswe set out to combine both optimal aggregateinterlock and the use of SBS polymers,in order to obtain both very stiff and fatigueresistant polymer modified base or binder coursematerial in a single formulation.8065Density (%)Increase in spherediameter ratioTheoretical backgroundon aggregate packingBasic notions associated withbinary gradingsThe first essential step, before studiesof multi-component systems may be undertaken,is to understand the factors involved inthe relationship between aggregate proportionsand porosity in 2-component systems.Figure 1 illustrates the evolution in the densityof a binary blend of coarse and fine spheresfor various sphere diameter ratios [13J.This figure reveals that as the ratioof average fine aggregate dimension-to-averagecoarse aggregate dimension rises, interaction effectsbecome more significant as well.(b)o0.25Volumic proportion of fine spheresFigure 1a) Apollonian aggregate structureb) Evolution in the density of a binary blend of coarse and fine spheresfor various sphere diameter ratios [13]Ideal case of a mix of an extremely fineaggregate with a coarse aggregateFor a situation in which one aggregateis very fine in comparison with the other(dFINEAoARSE - 0.008), Baron [2Jproposed to describe the void index variationof a mix by means of three straight lines (Figure 2).ED eUr"'opeanroada revIew 1 B • Spring 2011 • RGRA


DDDMix with highfines contentP < PxMix with mediumfines contentPX < P < P TMix with lowfines contentBaron defined two thresholds, Px and PI'which indicate the critical concentrationsthat allow eliminating interference effects.Within a binary mix with coarseand fine particles, threshold Px corresponds tothe maximum coarse aggregate concentrationthat can be combined with fine aggregatewithout altering the fine aggregatearrangement, whereas thresholdPT is equal to the maximum fine aggregateconcentration (1 -PT) for combination with coarseaggregate so as not to interferewith the coarse particle layout.Depending on whether the granular mixhas a high (p < px)' medium (Px < p < PT)or low (p > PT) content of fines,void index variation can be definedaccording to three distinct laws:• High content of fines in the mix, p < Px:I e = F (1 - p) + Dp I [1]where,- F is the void index of fines, and- D is a parameter of the wall effect (Figure 2).• Low content of fines in the mix, p > PT:e = (C + 1) P - 1 [2]where,- C is the void index of coarse particles (Figure 2).• Medium content of fines in the mix, Px < p < PT:e = Ep [2]where,- E is a coefficient determined graphically (Figure 2).P > PT...-...... .......0 •••••••o... ~~.~Figure 2Void index variation (e) in the case of a two-aggregate mixture,one of which is very fine compared to the other (according to [2])Px....PToObjective of the present studyBaron 's approach for optimal aggregate packing,first developed in the field of high-performancecement concrete in 1982 [2]. was transposedto the field of asphalt concreteat the Eiffage research centre in France.The main goal was to evaluatethe relevancy of such an approachin the asphalt field with typical French materials.The underlying question was: can we develophigh-performance dense asphaltby means of optimized gap grading?And, likewise, can we use more specificguidelines for aggregate structure selection?After publication of the first encouraging resultsobtained [14 to 16]. a very large experimentalprogram has been launched at the Eiffage researchcentre, including the evaluation of compactability,moisture resistance, rutting resistance, stiffnessmodulus and fatigue resistance as well [17].MaterialsTwo pure paraffinic bitumens comingfrom the same crude and refinerywere investigated: 35/50 and 35/45B("B" stands for "semi-blown") Pen Grade bitumens.Two PMB's made from these two pure bitumenswith 2.5% SBS (proprietary crosslinking process)were also investigated.Eventually, the analysis of recovered aged binderfrom reclaimed asphalt pavement (RAP) aggregateswas also carried out. Table 1 presents the resultsof conventional tests (Penetration at 25°Cand Ring & Ball Softening Point) performedon these different binders.BinderPen 25°C (mm/l0) 50ftening Point RiB (oqNF EN 1426 [18]35/50 3835/458 3735/50Hrosslinked2.5%5B535/45B+crosslinked2.5%5B53833aged RAP binder 10Table 1Conventional results on the studied BindersOnly one typical French aggregate naturewas considered: diorite crushed aggregatefractions (0/2, 014 and 10/14 mm) coming fromthe La Noubleau quarry. Limestone fillercoming from Saint-Hilaire quarry in FranceNF EN 1427 [19]53.56262.27171. 2»>european roads review 1 B • Spring 2011 • RGRA ~


L-____ -., GB5®: Eco-Friendly Alternative to EME2for long-Life & Cost-Effective Base CoursesInnovationfor Long-Life PavementsSieve (mm)161412.51086.34210.50.250.08was also considered. Moreover, some RAPaggregates coming from Touraine Enrobesasphalt plant (Eiffage TP Centre) were used.Table 2 gives gradation curves of each granularfraction . Average dimension of fillerwas determined by means of a Coulter®particle size analyzer.FillerPassing (%)La Noubleauaggregates0/2 0/4 10/14RAP Toul'S100 10093 9777 8922 725 63100 1.7 55100 96 0.4 4597 54 0.3 3268 37 0.2 2345 25 0.2 17100 31 18 0.2 1083 17 10 0.2 9• Fatigue resistance at 1Q°C -25Hz(NF EN 12697-24 standard, [24]) usingstrain -controlled test on trapezoidal specimens.Classical fatigue criterion, referencedas N f50, was used. According to it,fatigue life corresponds to the number of cyclesfor which stiffness modulus decreasesto 50% of its initial value. Strain amplitude valueleading to failure at one million cycles ishereafter called E6 (used in French designmethod SETRA-LCPC [25]).Aggregate packing optimizationresultsThe innovative use of a single-gapor even a double-gap graded curve is helpfulto get very dense asphalt mixes with great coarseaggregate packing (lower interaction betweenintermediate and coarse particles, d. Figure 2).Such single-gap graded curve was investigatedwith La Noubleau aggregates in the frameworkof this study. For more details, the scientificapproach of the iterative aggregate packingoptimization procedure is fully describedin reference [26]. Figure 3 illustratesthe final gradation curves obtainedafter optimizing the aggregate packing(with the La Noubleau aggregates)with a single 4/1 Omm gap.Average particle dimension, hereafter named d soDiameter (mm) 0.025 0.6 1.9 11 .5 5Table ZPassing percentage and average Particle Size for each Tested Granular FractionSegregationTests used for characterizingAsphalt ConcretesMany laboratory tests were conductedon asphalt concretes, including:• Compactability, measured with the gyratorycompactor (Ge), following the requirementsof NF EN 12697-31 standard [20].• Water resistance, measured from the so-calledDuriez test (NF EN 12697-12, [21]).This ratio is the French counterpart of TensileStrength Ratio value with Marshall samples.• Rutting resistance, evaluated at 60°Cwith the French Rut Tester in accordance withNF EN 12697-22 [22] .• Complex modulus at 15°C-10Hz(NF EN 12697-26, [23]) usingcylindrical specimens.Figure 3Skip gradation curves (referred to as "GBS") for the optimalquaternary aggregate blends vs that of the continuouslygraded reference "GBZ"Performance-relatedcharacterizationand related discussionRichness modulus (k) is basically the ratioof bitumen content to surface areaof aggregates and thus an estimationof binder film thickness. For more details,reader can refer to [7,27] .~ european roads review 1 S • Spring 2011 • RGRA


This parameter, of primary importance in France,was kept constant and equal to 2.55.This somehow low value for richness moduluscorresponds to 3.9% binder content by weightof aggregates (10% voL) for La Noubleau mixtures.Table 3 shows the performancesof the innovative GB5® gap-graded dense mixescompared to the reference Grave Bitume GB2material usually used as base course materialin France.Rutting resistance assessedfrom French Wheel Tracking testGB5 mixes exhibit great resistance to ruttingfor two main reasons: the first reason is related tothe well-interlocked and dense mixtures obtainedfrom the optimization of aggregate packing;the second reason lies on the factthat semi-blown and PMBs give high resistanceto rutting at high temperatures, especially at 60°C.FormulaGC100 gyrationsDuriez TestRut Depth (mm) E (MPa) E6 (10. 6 )3 10 4 cycles15C-10Hz 10C-10HzeTable 3Performancesof the GBS materialscompared tothe reference GB2material.La Noubleauaggregates witha 3.9% bindercontent by weightof aggregate(%vol.: l0.0%)BindernatureSpecifications for"Grave Bitume 2" (GB2)Specifications for "En robea Module Eleve 2" (EME2)%RAP %Air VMAR(MPa)80>70% 14,000 >13093 4.183 5.191 4.193 2.492 2.591 3.014,200 at4.1% air16,500 at2.7% air16,600 at2.7% air15,600 at3.2% air13,100 at2.9% air13,700 at2.5% air868990110115130Compactability evaluatedfrom Gyratory Compactor (GC)(ompactability is significantly improved:densities are increased by 2.3% up to 4.0%.Yet, the use of 10% (continuously graded) RAPslightly decreases compactability of the GB5 mix(7.2% air voids at 100 gyrations, instead of 5.9%),indicating that non-negligible interference effectsoccur between aggregate particles.This excellent compactability of such GB5has been confirmed on site during many experimentalroadworks in France and Spain.Compressive strength & moistureresistance assessed from Duriez testDirect compressive strength is increasedby 1.2MPa to 3MPa. Besides, moisture resistance("Duriez ratio "), which is far above the minimumspecification value for typical Grave Bitume GB2,does not seem to be influenced by the gradationsand PMB's used.Complex Stiffness ModulusFor a fixed bitumen nature and content,complex stiffness modulus of such well-interlockedand dense mixtures, measured at 15°(.1 OHz,is increased by approximately 17%.The proposed aggregate packing optimizationprocedure could be used in the frameworkof high-modulus mix design with slightly softer gradesthan usual (Penetrability at 25°( >30),thus enhancing both reclaiming abilityand fatigue resistance of asphalts mixes.Fatigue resistance(French two-point bending fatigue test)For fixed bitumen nature and content, fatigueresistance measured at 10 0 ( -25Hz is hardlyinfluenced by aggregate packing optimization.On the contrary, binder nature greatly influencesfatigue resistance: the use of both polymermodification (2.5% cross-linked SBS)and semi-blown bitumen lead to » >europeanroads review 1 B • Spring 2011 • RGRA lID


-Innovationfor long-life PavementsGB5®: Eco-Friendly Alternative to EME2for Long-life & Cost-Effective Base Coursesan increase of E6 value by about 24-29 10- 6individually and up to 44 10- 6 when combined.Note that the E6 value of 130 10- 6 (at 10°C-25Hz),obtained with 35/45B bitumen modified with2.5% of cross-linked 5B5, is an incredibly high valuefor an asphalt concrete with only 3.9% bindercontent.Eco-friendly alternative to EME2An alternative to the traditional high-modulusand high-binder content EME2 (for which bindercontent is about 5.5% to 6%) may be proposedfor long-lasting and cost-effective asphalt mixes.Considering the very encouraging resultspresented in Table 3 (with only 3.9%of bitumen by weight of the aggregate),at Eiffage Travaux Publics we set outto combine both optimal aggregate interlockand the use of semi-blown and/or 5B5 modifiedbitumens, so as to obtain both very stiffand fatigue resistant base/binder course materialin a single formulation .This has been done with manyaggregate natures (from France and 5pain)by using either single-gap or double-gapgraded curves and a tremendous numberof polymer modified and semi-blown bitumens.Obtained performances are close tothe specifications required for EME2(stiffness modulus of 14,000MPa at 15°Cand a fatigue resistance of 130 microstrainsat 10°C) with a significantly lower bitumen content(in the range of 3.8% to 4.8% by weightof aggregate). 5uch innovative mix design,which is referred to as GB5®, has been patented.The two following sub-sections presenta case study with comparative pavementdesign & environmental impact.Hypothesis for pavement design& material costThe French method for pavement designhas been used. Calculations presentedhereafter rely on the use of the so-calledALIZE software. The adjustment factor,named kc' that is used for determiningthe strain value Et,ad considered acceptableat the bottom of the GB5® base course,is considered as equal to 1 .3 (typical valuefor a French GB3/GB4 Grave Bitume base layer).Furthermore, the k c = 1 hypothesis is madewhen considering conventionalhigh modulus asphalt concretes(referred to as EME2), which usevery low-Pen grade bitumens(Penetrability at 25°C in the range 10-30 dmm).Broadly speaking, this kc coefficient adjuststhe results of the computation modelin line with the behaviour observedon actual pavements of the same type.For more details, the valueof this coefficient, for bituminous materials,is detailed in the French design manualfor pavements structures [25].In order to compare the costsof road structures with traditional EME2or innovative GB5® base course,the following orders of magnitudewere taken into account for material costs:• cost of 10/20 - 35/50 pen grade bitumen+ 40-60 € /t,• cost of 35/45B = 35/50 pen grade bitumen+ 40-60 € /t,• cost of 35/50 + 2.5%5B5 - 35/50 pengrade bitumen + 150-170 € /t,• cost of 35/45B + 2.5%5B5 - 35/50 pengrade bitumen + 200-220 €/tThe apparent specific gravities (ton/m 3 ) are:- p(BBM): 2.42 tlm 3 ,- p(GB5): 2.47 tlm 3 ,- p(EME2): 2.49 tlm 3 .Comparative pavement design,corresponding costs &related environmental impactsTable 4 presents a comparative pavementdesign using the ALIZE softwareand considering a "TC620" traffic category,a 4cm-BBM ("beton bitumineux mince")overlay and a "PF3" pavement formation class.The materials are the same ones listedin Table 3, together with their respectiveperformances.Innovative GB5 materials do havevery positive environmental and economicalimpacts when considering the reducedbase layer thickness and the reducedquantities of binder and aggregaterequired per square meter.Insofar greenhouse gas (GHG) emissionsare concerned, the carbon dioxide (C0 2)quantity (main GHG emissions generatedduring roadwork) associated to aggregate,pure bitumen and modified binder isrespectively equal to 10, 285 and 310 kgCO/t.Therefore, the proposed high-performance GB5®base layers may lead to a reduction in CO 2emissions by almost 30% in comparison withtraditional EME2-based pavementdesign (see Table 4).aD! europeanroads revew 1 B • Spring 2011 • RGRA


Thick Bituminous Pavement Structures. "TC620" Traffic Category.4cm-BBM Overlay. "PF3" Pavement Formation Class.Table 4Comparativepavement designwith La Noubleaumaterials, correspondingcosts & relatedenvironmental impacts(per square meter)TraditionalSolutionInnovative GB5® SolutionsEME2 GB535/45B GB535/50 GB535/45B+2.5%SBS +2.5%SBSBinder content Binder content Binder content Binder content= 5.7% = 3.9% = 3.9% = 3.9%Overlay 4cm BBM 4cm BBM 4cm BBM 4cm BBMBase course 16cm EME2 14cm GB5 12cm GB5 10cm GB5Differencein base layer thicknessDifferencein aggregate quantityDifferencein bitumen quantityDifferencein materials cost/m 2Differencein kg C0 2 eq. /m 2Reference-2cm (-10%) -4cm (-20%) -6cm(-10%)-10%-28%-23%-24%-20% -30%-39% -48%-27% -38%-17% -28%References road worksof the years 2010-2011Almost 10 full scale suitability tests were firstcarried out on several Eiffage plants in 2010.These preliminary field trials allowed validatingthe technical choices before generalizing GB5®mix design on each Eiffage site.The great compactability of GB5® mixtures(with either single-gap or double-gap gradations)was confirmed on more than 30 large scaleroadworks so far.Several aggregate natures were studiedin laboratory and used on the job sites. Four mainnominal maximum particle sizes (NMPS) were tested:11 mm, 14mm, 16mm and 20mm. Both single-gapgraded curves and double-gap graded granular curveswere successfully investigated. Semi-blown 20/30,35/50, 50/70 and 70/100 pen grade binders wereused. Furthermore, polymer modification wasalso carried out (SBS with or without a proprietarycross-linking procedure referred to as Biprene®)for most of our full scale suitability tests in 2010.The use of RAP in GB5® is common in the 10-35%range. GB5® mixtures were applied bythe paver-finisher and were very easily compactedby double-roll vibrating compactors(Photos 1 and 2). By using GB5® mixture,there is no need for pneumatic tyre rollers,the final density being in the rangebetween 2.5% to 6%. GB5® layer thickness wasgenerally between 7cm and 16cm.Because of the skip gradations used,compaction of 6cm to 17cm layers with NMPS(nominal maximum particle size) is possible.Photo 1Paving GB5® Ol14mm high-performance asphalt with La Noubleau aggregatesand 35145B bitumen in the Tours area. In-place density: 96.4% ; stiffness modulusmeasured in indirect tension configuration E *(15°C-10Hz): 14,1 OOMPaPhoto 2Paving GB5® Ol14mmwith Budillon·Rabatel'!III"~ aggregates and SBSmodified binderBiprene® 41 and15% RAP near Chambery.In·place density:97% ; stiffness modulusin indirect tension modeE*(15°C·10Hz):15,900MPaeuropeanraads review 1 B • Spring 2011 • RGRA lID


Innovationfor long-life PavementsGB5®: Eco-Friendly Alternative to EME2I for Long-Life & Cost-Effective Base CoursesAfter several months (trials in 2010-2011),these different sites were revisited in order to assessthe condition of the pavement and/or to take coresto assess density and complex or secant modulusof these field cores in IDT (indirect tension) mode.This follow-up is very encouraging and confirmsthe great performances initially obtained in laboratory.Last but not least, in the frameworkof the so-called Road Innovation Charter procedureof Setra (French acronym which stands for"Service d'etudes sur les transports, les routeset leurs amenagements") the innovative GB5®project has been recently awarded.In 2011, a Road Innovation Charter will be signedwith several General Councils and Setra;afterwards, several GB5® projects will be undertakenin different France's climatic zonesunder very high traffic. A five-year follow-upby Setra will be planned from then onfor validation of this new technique.ConclusionsThe aggregate packing methods first developedin the field of high-performance cement concreteswere successfully transposed to the fieldof asphalt concretes. They enabled developmentand design of high-performance asphalt mixturesbased on single or double-gap-gradeddense grading curves and the use of semi-blownand/or SBS modified binders.Laboratory results were found to be very encouraging.Such combination of innovative single- ordouble-gap-graded curves with semi-blownand/or SBS modified bitumens (at such a low bindercontent as 3.9% by weight of the aggregate),leading to very stiff and fatigue resistant polymermodified base or binder course materialsin a single formulation, has been patented.Several full scale roadworks weresuccessfully realized in France and Spain as well,at either hot (170°C) or warm (125°C)or even half-warm (90°C) temperature.To some extent, these HPAs used for baseor binder courses could provide real long-lifepavements that do not deteriorate structurally,needing only timely surface maintenanceto preserve their overall condition.Finally, the proposed approach is considerablydifferent from those of SMA design and French EME2design, since bitumen content is very low(about 4% instead of the more traditional rangeof 5.5%-6% by weight of the aggregate)with still very high performances.Reductions in binder quantity per ton of mix(despite the high cost of SBS modifier)and in base course thickness (due to enhanced stiffnessand fatigue properties) lead to a cost effectiveand eco-friendly perpetual pavement design . •References111 A. Caquot "Le r61e des materiaux dans Ie betan", Memoires de la Societedes ingenieurs civils de France. pp. 562-582. July-August 1937 [In Frenchl121 J. Baron. R. Sauterey. "Le beton hydraulique: Connaissance et pratique".Presses de l'Ecole nation ale des Pants et chaussees, Paris. 1982 lin Frenchl131 F. de Larrard. "Formulation et proprietes des betons a tres hautesperformances". Rapport de recherche LPC N"149, ISSN 0222-8394. March1988 [In Frenchl141 F. de Larrard. T. Sedran and D. Angot. "Prediction of the Packing Density ofGranular Mixtures with the Solid Suspension Model. I: Theoretical Basis andCalibration ". Bulletin de liaison des Laboratoires des Pants et Chaussees.N'194,1994151 F. de Larrard, T. Sedran, "Optimization of ultra high-performance concreteby the use of a packing model ". Cem. Can. Res. 24/6, 1994161 F. de Larrard, T. Sedran, "Mixture-proportioning of high-performanceconcrete" . Cem. Can. Res. 32, 2002171 J.-F. Corte, H. Di Benedetto, "Materiaux Routiers 8itumineux 1: descriptionet proprietes des constituants", Lavoisier. 238 p., 2004 lin Frenchl181 K.E. Cooper. S.F. Brown, G.R. Pooley, "The design of aggregate gradings forasphalt basecourses", Proceedings of the Association of Asphalt PavingTechnologists, 1985191 R. Roque, S. Huang and B.E. Ruth, "Maximizing shear resistance of asphaltmixtures by proper selection of aggregate gradation ", 8th Int. Soc. for AsphaltPavements, Seattle, 19971101 S. Kim, A. Guarin, R. Roque and B. Birgisson, "Laboratory Evaluation forRutting Performance Based on the DASR Porosity of Asphalt Mixture", RoadMaterials and Pavement Design, Vol. 9, Issue 3, 20081111 H. Baaj, H. Di Benedetto and P. Chaverot, "Effect of binder characteristicson fatigue of asphalt pavement using an intrinsic damage approach", RoadMaterials and Pavement Design, Vol. 6, Issue 2, 20051121 S. Dreessen, M. Ponsardin, J.-P. Planche, A.-G. Dumont, M. Pittet. "Durabilitystudy: Field aging of conventional and cross-linked polymer modified bitumens",UMU (Liverpool John Moores University) conference, 20111131 E. Guyon, J.-P. Troadec, Du sac de billes au tas de sable, Editions OdileJacob, 19941141 D. Perra ton, M. Meunier, A. Carter, "Application of granular packingmethods to the mix design of Stone MatrixAsphalts (SMA)", Bulletin de liaisondes Pants et Chaussees, N'270-271, 20071151 F. Olard, D. Perratan, "On the optimization of the aggregate packingcharacteristics for the design of high-performance asphalt mixes", RoadMaterial and Pavement Design, vaLlI, Special Issue EATA Parma 20 101161 F. Olard, D. Perraton, "On the Optimization of the Aggregate Packing forthe Design of Self-Blocking High-Performance Asphalts ", Congress of theInternational Society for Asphalt Pavements, Nagoya, 20101171 F. Olard, P. Huon, S. Dupriet, C. Billet, Graves-bitume GB5"': Une nouvellegamme d'enrobes a hautes performances pour couches d'assise et de liaison,Revue generale des routes et des aerodromes (RGRA) n'888, octobre 20101181 Standard NF EN 1426: Bitumen and bituminous binders. Determination ofneedle penetration at 25'C, 20001191 Standard NF EN 1427: Bitumen and bituminous binders. Determination ofthe Ring and Ball softening point, 20001201 Standard Nf EN 12697-31: Bituminous mixtures. Test methods for hot mixasphalt. Specimen preparation by gyratory compactor, 20071211 Standard Nf EN 12697-12: Bituminous mixtures. Test methods forhot mix asphalt. Determination of the water sensitivity of bituminousspecimens, 20081221 Standard Nf EN 12697-22: Bituminous mixtures. Test methods for hot mixasphalt. Wheel tracking, 20031231 Standard NF EN 12697-26: Bituminous mixtures. Test methods for hot mixasphalt, Stiffness, 20041241 Standard Nf EN 12697-24: Bituminous mixtures. Test methods for hot mixasphalt, Resistance to fatigue, 20041251 SETRA-LCPC. "french design manual for pavement structures", EditionsLCPC & SETRA, Paris, 19971261 f. Olard. "Innovative DeSign Approach for High-Performance AsphaltConcretes for Long-Life Base and Binder Courses by Use of Aggregate PackingConcepts and Polymer Modified Binders", Proceedings of the TransportationResearch Board annual meeting, Washington D.C., 20111271 fontana M., Di Benedetto H., Dumont G., Voies de circulation II, Chapitre 5.Cours de I'Ecoie polytechnique federale de Lausanne (EPFL), 1998 lin frenchl~ e u ropean roads review 1 B • Spr ing 2011 • R GR A


Lars LADEHOFFLaboratory ManagerColas(Denmark)Xavier CARBONNEAUHead of asphalt divisionCST Colas(France)---iITrafic no~se reduction]Noise-reducing asphalt mixes:The Danish ExperienceHerning By PassThe roll-out phase of new special productsalways involves trial sections on which performancelevels are monitored over time. However,these sections are rarely analyzed in themedium-term. This article presents a programset up by Colas Denmark to help disseminatetechniques designed to reduced rolling noise,in which the 'oldest' results used in the studydate back to 5 years under traffic. The texthereunder illustrates their mastery of the processes,and underlines the opportunities thesetechniques offer by always being able to providea tailor-made solution that will be the bestcompromise from a technical and economicalviewpoint, in terms of feasibility, cost, noise reduction targets, without sacrificingsafety or skid resistance.IntroductionRoad projects today increasingly take intoconsideration the concepts of improved city livingalong with the environmental and social impactof infrastructure. As such, Colas showcasedits expertise by developing noise-reducing asphaltmixes that help diminish traffic noise up to 9dB(A).Originating in France, the new techniquesenjoyed rapid development in other countries,due to omnipresent noise issuesand decision-makers' desire to test and promotethese techniques. This was particularly truein Denmark, where as early as 1990,noise had become one of the main politicalissues that needed to be tackled.Against this backdrop, a number of productswere launched and Colas Denmark was involvedin a series of trials [1]. the findingsof which are presented hereunder.Background on noise issuesTransferring technology and/or new processesis always an enriching experience,both for the company that is trying to promoteits techniques and its expertise,and for the customer who is trying to solvea specific problem, but who may be anxiouswhen faced with new technology.With noise - as is the case with a numberof other performance factors, the multitudeof physical and mechanical causes that generatenoise have long since been identified [2, 3J.Noise comes from motors, the movementof mechanical parts and tire/pavement interaction.The characterization of noise is alreadyhost to a number of methods.Some have been standardized [4].providing an accurate description of the methodsand measuring conditions. Others are currentlyin use as well, but have not all necessarilybeen standardized [5J .These methods are almost all complex.And the situation gets even more complicatedwhen decision-makers have to comparethe findings of trials performedwith different methods, not to mentionthe impact of the surroundingsof the test area and weather conditions(temperature, wind, humidity) on the findings. »>european roads review 1 B • Spring 2011 • RGRA ED


Tratic noise reductionNoise-reducing asphalt mixes:The Danish ExperienceIn fact, deviations can be quite significanton the exact same surface [6].To make things easier for decision-makersand to ensure that the elements on whichwe can base asphalt mix evaluationsare as accurate as possible, a protocolto help validate mixes was designed, based onour experience over the last few years [7].along with mix classification methods usedin as objective a manner as possible [8].Above and beyond measurements madedirectly following application, long-lastingperformance remains one of the main issuesat hand. The initial gain can be very significantcompared to the former surfacing,but the improvement must last over time,for the duration of the course's service lifeif possible.As part of the promotion processfor a new technique that customers are not yetfamiliar with, mix design needs to be explained,even if its efficiency is no longer a doubt.European standardization has homogenizedpractices for a number of asphalt mixcharacteristics, making this stageall the easier (EN 13108-1) [9] . In noise-reducingformula, the mix design phase is extremelyimportant, especially in terms of optimizing air voidcontent in-situ, and water resistance.Noise absorption characteristics then comeinto play, and their evaluation is not partof current mix design practice.Lastly, and this is one of the most interestingaspects of the international development program,specific local features must also be included.These can comprise raw material issuessuch as a limited supply of grading curve fractions,as well as the offer in terms of bitumen binder.The local specifics can also include weather,traffic and the use of special equipmentsuch as studded tires, not to mention requirementsfor light colored surfacing (to secure a certain lightreflection during dark), and more.In Denmark, the developments presentedhereunder take many of these constraintsinto account, which sometimes led tothe redesigning of certain mixes. In the end,noise reduction performance goals were reached.Highway M10Microville in DenmarkAs is often the case in Denmark, the approachwas launched with a comparison of a seriesof mixes applied during the summer of 2004on a section of Highway M1 0 between Copenhagenand K0ge. The average daily traffic is around70,000 vehicles. Four mixes with grading curvesof 6 to 8mm were applied on 1,350 meter longsections, which were then compared towearing courses with conventional AB 11 t(11 mm Dense Asphalt Concrete) mix designs.The sections were located as follows in Table 1.31 ,SOOkm 28,800kmISMA 6P Combifalt 8AB l1t SMA IN 8 Microville 8---------- ----r--------------32,700km 2B,BOOkm ~;3Table 1Location of trial sections on Ml0The grading curves of the trial mixes are listedin Figure 1.% passing10090807060504030../~-.........::: ....I20......-::~o0.125 0.25 0.5Microville 8SMA-LN 8Sieve (mm)_ SMA6P__ AB11tFigure 1Grading curves of trial mixes applied on Ml0The Microville was not designedwith the conventional grading curve,because the latter required modificationdue to local availability. The design studywas focused on evaluating workabilitywith a gyratory shear press and water resistancewith a Duriez test.-/''l- Combifalt 8I/ If/ JI 1// VIII(j".s:t:oZ4 5.6 8 11.2&:I europeanroads review 1 B • Spring 2011 • RGRA


The findings are detailed in Table 2.Photo 1 shows the surface appearanceof Microville 8.Gyratory shear press test EN 12697-31Results onMicroville 0/8Void content after 25 girations 17.6%Water resistance Duriez test NF P 98-251-1Compression strength7 MPaI/C 93 %Table 2Measured mechanical characteristics for Microville~uNoise was tested on the section usingthe Statistical Pass-By method (SPB)and close range method, the findings of which -ranging in date from a few weeks to one yearafter application - are included inTechnical Notes no. 21 and 35 published bythe Danish Road Directorate [10,11].In addition, measures were performedon the same sections using Colas' specially-designedequipment as shown in photo 2. The sectionswere characterized with different methods,with noise recorded near a tire each time. The Colasmethod uses the right rear tire, whereas the DanishRoad Directorate calls for the use of a trailer wheel,which may be streamlined. We now have 5 yearsof feedback from monitoring this project.The findings from test performed with the methodsdescribed above are listed in Table 3.For close range data, the speed was 80km/h. »>Photo 1Surface of Microville 8Photo 2Close range noise measures used by Ecoliant (Colas Group)AB 11t SMA LN 8 Microville 8 Combifalt 8 SMA 6PSPB I (after application) 84 83.2 81.2 81 .8 82.6SPB I (year) 84.1 84.1 81 .8 83.1 82.6CPX I(09/04) [1 ]CPX ISO(09 /04) [2]CPX I(10/05) [3]CPX I(07/09) [4)99.4 99.4 99.2 99.9 98.698.9 99.3 98.4 97.9 96.899.1 98.6 97.6 98.9 98100.1 100.3 99.4 100.7 99.2[1] performed by DGMR for the Danish Road Directorate[2] Colas measures[3] average findings by Carl 8ro monitoring at 1 year~[4] M+P monitoring at 5 years '0uTable 3Noise measurements in dB(A) on Highway Ml0 trial sections (from Colas and [10] and [11])european r o a ds review 1 B • Spring 2011 • RGRA DII


Trafic noise reductionNoise-reducing asphalt mixes:The Danish ExperienceSurfacingAB l1tSMA IN 8Microville 8Combifalt 8SMA 6PMicroville still has the best noise-reducing capacity,regardless of the characterization method used,and its performance remains excellenteven after 5 years.In addition to noise, skid-resistance was studied onthe same sections, using the Danish Road Institute'sROAR method. The results presented in Table 4were published in technical note 52by the Danish Road Directorate [12).MeasuresMeasures(August 2004) (September 2006)0.64 0.520.71 0.630.75 0.630.76 0.70.69 0.64 ~vTable 4Average skid-resistance values measured with ROAR test (extract from (11))Rugosoft developmentThe projects described above were amongthe first steps in the development processof noise-reducing asphalt mixes. The pathto progress continued with the first Rugosoftproject in 2005 in the town of Aalborgwhere a 2,000m 2 test section was applied.In September 2006, a larger project was launchedon a 4-lane roadway into the town of Holbaek,illustrated (photo 4). The structure bears trafficof up to 14,000 vehicles per day,which means that a modified binderfrom the Colflex product line was usedto ensure long-lasting performance.Noise performance was an issue on this projectfor local residents, and close-rangeCPX DK findings showed 88.8 dB{A) at 50km/hrecorded on May 2007.The main conclusions we can make from these studiesis that all of the mix design formulas comply withDanish criteria in terms of skid resistance,and that noise-reducing mixes continue to performin this field well over time.Photo 3Applying Microvilleon the HerningbypassMicroville 8 showed excellent behavior,with significant. long-lasting noise reduction combinedwith high-quality skid-resistance. As early as 2005,the technique was used in Copenhagen, as well ason a major project that required 15,750 tons(over 300,000m 2 ), on the Herning bypass (photo 3).This project provided an opportunity to pursueresearch on this technique with a trial sectionusing a lower grading fraction - 6mm.The mix was redesigned to include white materialin the aggregates because the surface had to be lightcolored. In-situ testing showed that the techniquewas perfectly mastered, ensuring full compliancewith theoretical design and thicknesses, good bondto existing substrate and conformity with forecastair void content. Tests on the section showed89 dB(A) at 50km/h using a close range CPX I test.Photo 4Rugosoh Holbaek projectSince that time, Rugosoft has enjoyed regulargrowth in Denmark, with several projectsfrom 10,000 to 20,000m 2 in Copenhagen and Vejlein 2007 and in Golstrup and Skive in 2009.Tests performed on the Holbaek projectsone year after application and measuresmade after application at the Vejle projectplaced the mix in the B category for measuresat 50 and 80km/h, in compliance with the Danishnoise-reducing surface classification system [8) .~ european roads revIew 1 B • SprIng 2011 • RGRA


Nanosoft developmentResearch performed in the Colas Groupproved that noise reduction could be takena step further, by optimizing the mix's aggregateskeleton to ensure a network of very small,regularly shaped communicating voidsthat absorb a maximum amount of noise.This idea would serve as the cornerstonefor the development of Nanosoft,the goal being to maximize noise absorption,which is quantified with impedance tube testingas illustrated in figure 2. A wide band sound signalis broken down as an incident and reflectivecomponent determined by the relationshipsbetween acoustic pressures. Three frequencyresponses are calculated to determinethe absorption coefficient u.Reflection/actor R = H , - H , e j2k (/o,) -absorption coefficient a = I -IR'IH , - H ,The latest phase of development was markedby the first Nanosoft project performed in 2007in the town of Vejle (photo 5). The Nanosofttechnique is the definitive step in optimizingasphalt mixes for noise reduction purposes.»>where- H, : frequency response;- Hi: incident frequency response,- H r: reflected frequency response,- k: number of wave,-I: distance between microphone and specimen,- s: space between microphones.This characteristic quantifies the noise absorptionof the wearing course in the frequency rangeof 200-1 ,600Hz.D La = -10 IOg [1 - 2 a ,P r,ajJiCOIOisespeC(,um 12. P'rafficnoisespeClrumThen the DLu is calculated with the traffic noisespectrum in order to get the highest DLu'Photo 5First Nanosoh section in VejleFigure 2Impedance tubewith 2 microphoneseuropeanroods revIew 1 B • SprIng 2011 • RGRA &I


Noise-reducing asphalt mixes:The Danish ExperienceNanosoft's ultimate performance levelsare based on the use of an even smaller gradingsize - 4mm - with no modification in surfaceskid-resistance. This was verifiedon a number of occasions, initially in France [13] .Small grading sizes mean a very homogenoussurface after compacting. From a noise-reductionstandpoint, the aggregate skeletonprovides porosity that dispersesa maximum amount of energy in the mix'sair void network, thus limiting rolling noise.Figure 3 illustrates this characteristicvia a cross-section of a Nanosoft specimenobserved with X-ray Tomographyand a 3D view of the existing communicatingair void networks. The mix's distinct physicalcharacteristic, verified by observation,provides maximum absorption.Findings show that the average diameterof communicating air voids is roughly 1 mm.Measures taken in-situ have once again confirmedthe surface's high quality performance levels.In this case, noise was measured with close rangeCPX DK at 50 and 80km/h in compliance withcurrent Danish standards, at Vejle site.To date, Nanosoft is the only productto have received the A-level classificationat both 50 and 80km/h as per localreference charts [8].ConclusionIn order to respond to the expectationsof local residents, the Danish Government,pushed by its strong desire to progressin the mastering of technical solutions,launched a number of trial sections.On each project, Colas Denmarkwas able to highlight its expertiseand the perfect control of available techniques.The Group's full product range can offer a solutionthat is tailor-made to fit with a varietyof technical and economic issues, taking intoconsideration noise-reduction requirements,local availability of materials (aggregate size)and traffic. Because skid-resistance remainsexcellent, user safety is never compromised.Similar success has been recorded in Polandwith now more than 250,OOOm 2 for Rugosoftand around 90,OOOm 2 for Nanosoft and in Hungaryyet around 20,OOOm 2 of Rugosoft . •Bibliograph_y __Figure 3A cross section of Nanosoh using X-ray tomographyand the existing communicating air void content in the mix11 J "Historical development of noise reducing wearing courses in Denmark"l.ladehoff.IRF lisbonne 201012J "Tyre/Road noise reference book". U. Sandberg. lA. Ejsmont. Informex200213J « Reduire Ie bruit pneumatique chaussee 1 P. Bar, Y. Delanne, 1993,Collection du lCPC14J NF EN ISO 11819-1. Acoustics Measurement of the influence of roadsurfaces on traffic noise. Part 1: Statistical Pass By method. March 2002ISJ « Synthese des methodes de mesure du bruit de roulement I, F. Besnard.Revue generale des routes et des aerodromes (RGRA), n° 803, fevrier 2002.pp 47-50[6J « Comparaison entre mesures au passage et mesure en champ proche.Bilan d'une experimentation I . J.-l. Gautier, Revue genera Ie des routes etdes aerodromes (RGRA), n° 803, fevrier 2002, pp 51-5517J « Performances acoustiques in-situ des revetements de chaussees.Methode experimentale de caracterisation, de verification et de suivi I.CFTR Info, Note N"20 janvier 2010[8J "Noise classification - asphalt pavement" Danish road institute Technicalnote 61. 2007[9J EN 13108-1: Bituminous Mixtures Material specificationsPart 1 Asphalt concrete (Feb 2007)[10J "M~ ling af trafikst0j fra vejbelaegninger p~ M 10 ved Solroo " Vijketniskinstitut. Esktemt notat 21, 2004111J "Test of thin layers on highway - Year 1 measurement report"Danish road institute Technical note 35112J "Traffic safety And noise reduction - Thin layers" Danish road InstituteTechnical note 52, 2007I13J « Nanosoft 1 P. Pringuet IRF lisbonne 2010&I euro p ean roads rev i ew 1 8 • Spri ng 2 011 • RGRA


Safety-enhancing achievements .~Anti-rutting solutions;.!TEN Construction Programme :Pavement design methoClsRoad Noise Barrier .....Concrete pavements '~ ,Pavement recycling.:,_"Innovative bituminous wearing cou ~sesTechnology transfer ,' ..Innovation . ';,:; ..Infrastructure developmentin South-East Europe-'~,:,;'Test facility in MinnesotaConcrete roads >Bitumen Emulsions .Climate change:_"Innovation, a catalyst for sustainableDedicated right-of-way "Public transport ,)The Silk Road. :':Mastic asphalt wearing... and more to come


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