Achieve better roads in Poland while saving resources with ... - Nynas

Achieve better roads in Poland while saving resources
with French function dissociation concept
Yves Brosseaud - Laboratoire Central des Ponts et Chaussées (France)
Bogdan Bogdanski - Roads Laboratory of GDDKiA Poznan (Poland)
Didier Carré - Product Manager - Nynas Bitumen (France)
Summary
The efficient allocation of resources is the key for durable development in general and in
particular in Road Construction. Experience has demonstrated that a technology embracing
too much function is wasting valuable resources. Skid resistance and structural strength
have to be optimised independently to reduce the construction and maintenance expenses.
Thin Surfacing technology (Béton Bitumineux Très Minces) is reducing the need for high
PSV required for long lasting skid resistance whereas High Modulus Hot Mixes (Enrobé à
Module Elevé) are allowing construction of thinner pavements.
In order to help Poland to respond to the increase of volume and severity of road traffic
happening with the enlargement of European Union, a technical and institutional cooperation
– COCOP - has been organised. This joint project involves the French Road
Direction, the Polish Public Road Direction and the Polish Highway building and
management Agency.
The Roads Laboratory of GDDKiA Poznan and the French Road and Bridge Central
Laboratory (Laboratoire Central des Ponts et Chaussées) have experimented in real scale
the Function dissociation concept to a road overlay near Poznan.
In co-operation with Strada and Nynas Spzoo, this project has consisted in the joint
formulation of a Thin Surfacing and High Modulus Hot Mix, the design of the overlay and the
construction by PRID Nowy Tomysl of the overlay during August and September 2002.
This paper is describing the co-operation process during this project and is giving
recommendations and perspectives for the optimisation of resources in the maintenance of
Polish road network.

Achieve better roads in Poland while saving resources
with French function dissociation concept
Yves Brosseaud - Laboratoire Central des Ponts et Chaussées (France)
Bogdan Bogdanski - Roads Laboratory of Poznan (Poland)
Didier Carré - Product Manager - Nynas Bitumen (France)
1. Polish and Franch co-operation for safer and longer lasting roads
The efficient allocation of resources is the key for durable development in general and in
particular in Road Construction. Experience has demonstrated that a technology embracing
too much function is wasting valuable resources. Skid resistance and structural strength
have to be optimised independently to reduce the construction and maintenance expenses.
Thin Surfacing technology (Béton Bitumineux Très Minces) is reducing the need for high
PSV required for long lasting skid resistance whereas High Modulus Hot Mixes (Enrobé à
Module Elevé) are allowing construction of thinner pavements.
In order to help Poland to respond to the increase of volume and severity of road traffic
happening with the enlargement of European Union, a technical and institutional cooperation
– COCOP - has been organised. The theme of this joint project involving the
French Road Direction, the Polish Public Road Direction and the Polish Highway building
and management Agency is the formulation of hotmix to reduce rutting.
The Roads Laboratory of GDDKiA Poznan and the French Road and Bridge Central
Laboratory (Laboratoire Central des Ponts et Chaussées) have experimented in real scale
the Function dissociation concept to a road overlay near Poznan. The LCPC has participated
to the selection of components, the mix design, the production, laying and control of an
experimental overlay of a structurally damaged road near Poznan – RN 2 in August and
September 2002 as well to a seminar presenting the results of this co-operation.
Strada and Nynas Spzoo have co-operated to this project in the selection and supply ot the
binders used respectively in the Thin Surfacing (Béton Bitumineux Très Mince here after
BBTM) and High Modulus Hot Mix (Enrobé à Module Elevé her after EME). These two mixes
have been designed to give good surface characteristics for better safety and good fatigue
and rutting resistance to reduce maintenance cost while preserving material resources.
This paper is describing the co-operation process during this project and is giving
recommendations and perspectives for the optimisation of resources in the maintenance of
Polish road network.
2. Adapting BBTM and EME technologies to the Polish context
Property Voids PCG Duriez Modulus Fatigue Rutting
Unit [%] [voids %] [r/R in %] [MPa] [ε6 in µstrain] [%]
BBTM 1 9 à 16% 10 à 18* > 0,80 Nil
Nil < 15 **
EME 2 à 6% < 6 * > 0,75 >14000 > 130 < 7,5 ***
GB 4 5 à 8% < 9 * > 0,70 > 11000 > 100 < 10 ***
*void content measured after a given number of gyrations: 25 for the BBTM, 100 or 120 for EME or GB
respectively for larger stone size 14 or 20 mm.
** evaluation of mechanical stability with a rutting test on 50 mm thick slabs submitted to 1000 cycles
at ambient temperature and 3000 @ 60 °C.
*** rut depth after 30000 cycles, @ 60 °C on 100 mm thickness slabs.
Table 1: extract standard properties BBTM 1, EME 2, base course mix GB 4 (Grave Bitume)

The objective of this project was to adapt to the Polish conditions:
• a reinforcement binder layer hotmix close to the EME type 2 French standard [1] with high
compacity and a sufficient low temperature behaviour binder
• a high and long lasting skid resistant thin surfacing hot mix within the BBTM type 1 French
standard [2] which will be compared to a SMA.
The standards mechanical properties of materials used in this project are summarised in
Table 1.
3. Binder course mix design – EME
3.1. Objectives and design principles
In order to take in account the Polish context, a 20/30 binder has been chosen instead of the
10/20 typically used in France, which may be too hard regarding the more severe winter
conditions of Polish climate. The mix design targets are as follows:
• a stiffness modulus at the minimum of the EME 2 standard (i.e. 14000 MPa) ;
• a lower fatigue resistance than for EME 2 (e.g. an admissible strain for 10 6 cycles of
110 µstrain instead of > 130 for EME 2) ;
• a rutting resistance of 5 % better than EME 2 standard (< 7.5 %) ;
• a binder thickness equivalent to the EME 2 (Richness modulus 1 K > 3.4)
This mix design targets are a balance between the EME 2 and GB 4 standard (see Table 1
and [3]) with a larger Richness Modulus (K > 2.9 for a GB 4) to achieve a lower void content
(close to 5 to 6 %). This allows the use of a surface course mix with relatively high void
content as a BBTM. This not possible with the traditional GB which have a void content of 9
to 10 %.
For the pavement design, the correction factor Kc is set to 1.3 as for the GB instead of the 1
of the EME.
3.2. Components selection
3.2.1. Aggregates
The sands and aggregates are supplied from the same quarry: Wilkow. The binder content
had to be increased further their very high specific gravity (close to 3.0 g/cm³). Fully crushed
sands and aggregates, they have a good angularity and flakiness. All fractions have
presented a consistent grading with exception of the sand delivered for the job with a filler
content measured at 19 % whereas 13 % was found on the lab samples. The polish stone
value (PSV) of 48 is also good.
According to the French standard NF P 18-540, the aggregates are of “B III a” class, which is
required for BBTM, laid under heavy and high-speed traffic. This material can be used also
for the EME for which the required class is only “D III a” class.
3.2.2. Binder – Nynas 20/30 EME
Nynas Spzoo has supplied the Nynas 20/30 EME specially designed for this project on the
base of the 20/30 class of EN 12591 standard (requirement values in bracket) :
• Penetration @ 25 °C: 25.3 1/10 mm [20-30]
1 Richness modulus K is related to the binder thickness:
K = Binder content * (MVRg / 2,65) * (1/ (Σ) 1/5 )
100*Σ = 0,25 G +2,3 S + 12 s + 135 f
with : Binder content in ppc
MVRg: specific gravity of the aggregates
100*Σ = 0,25 G +2,3 S + 12 s + 135 f
Weight proportions: G larger than 6.3 mm; S between 6.3 and 0.315mm; s between 0.315 and 0.08mm, f smaller
than 0.08 mm.

• R&B: 57.6°C [55-63]
• RTFOT ageing
• Residual penetration : 72 % [> 55%]
• R&B 63.4 °C [>57]
• Delta R&B 5.8 °C [

3.8. Conclusion
This 0/16 reinforcement hot mix fits with a GB 4 well adapted to the Polish context with a
good durability given by a high binder content of well-balanced penetration binder and a low
void content.
3.9. Polish specification project
The Polish Road and Bridge Institute (no 63) have proposed a project of recommendations
for high modulus hot mixes. According to the French experience, the following observations
can be made regarding their mechanical requirements on the mix:
• If two types of EME have been standardised in France, only the EME 2 is used for its
structural impact in reinforcement. The EME 1 is redundant with a conventional base
course hot mix with increased rutting resistance. To avoid confusion, the
standardisation of only one EME is recommended for Poland ;
• Creep modulus: the LCPC rutting is used in France where there is not enough
experience with this creep modulus test ;
• The modulus is measured @ 10 °C and 10 Hz instead 15 °C and 10 Hz in the French
standard ; this will lead to a decrease of modulus ;
• The 4-points bending fatigue @ 10 °C and 10 Hz test cannot be correlated to the 2points
bending LCPC fatigue @ 10 °C and 25 Hz test.
The French mechanical requirements are resulting from the comparative laboratory and real
scale experiment between the mechanical test method and measures on LCPC fatigue
carousel. In Poland, the requirements have to be validated according to the road design
parameter (test and design temperatures) and to correlation between laboratory and real
scale experience.
4. Surface course – BBTM
4.1. Objective and design principles
As the BBTM 2 can present a too high void content for the Polish weather conditions, a
BBTM 0/11 of type 1 has been formulated with a Polymer modified Bitumen Colflex N
supplied by Strada.
4.2. Components selection
4.2.1. Aggegates
The aggregates and sand are of the same origin as for the EME (see 3.2.1).
4.2.2. Binder – Colas Colflex N
The Colflex N is a PmB of 50/70 penetration class SBS modified bitumen and was complying
with the sales specifications of Strada :
• Penetration @ 25 °C : 49.8 1/10 mm
• R&B temperature : 53.8°C
The adhesion on 8/11 aggregates from Wilkow was excellent.
4.3. Gyratory compactor
Further to lack of aggregates, only one Gyratory Compactor test has been performed.
Nevertheless, the result was considered sufficient as no dispersion has been observed
during the evaluation of the EME.
As the two formulas tested behaved relatively similarly, the 5.3 ppc binder content was
preferred for a good coating without excess of binder. (see Table 2).

4.4. Water sensitivity
The Duriez water sensitivity test performance of the BBTM is excellent most probably
because of the very good adhesivity of the Colflex N binder (see 4.2.2).
Giratory compactor V 10 gyrations V 25 gyrations V 100 gyrations V 200 gyrations
17 %
13.1 %
Duriez r / R = 0.89 Duriez Voids
8.4 %
Mechanical stability
3000 cycles @ 60°C
50 mm thick slab
Rut depth
10.8 %
Nota : only one
slab tested
7.5 %
Voids filler with
air and binder
20.5 %
Texture before
test
HSV = 1.4 mm
5 %
Voids filled by
binder
59 %
Void (γ in the axis)
11.5 %
Table 2 Summary of test performed on the BBTM by LCPC
4.5. Surface texture
The mechanical stability is measured by a rutting test performed on a 50 mm slab after 1000
cycles at ambient temperature and 3000 cycles @ 60 °C (see Table 1 and Table 2). The
10 % rut depth is lower than the 15 % specification with a texture maintained during the test.
Some stone loss during the test can be related to the low Ring & Ball temperature of the
binder below the test temperature (see 4.2.2)
4.6. Conclusion
The surface course 0/11 hot mix formulated is compliant with the target: BBTM 1. The type 2
would have been too open for the Polish climate but a 0/6 mm type 1 could give anyway
already good noise reduction provided that particular care is given to the grading of the
aggregates fraction and to the their shape.
5. Reinforcement design with Alizé
Using the Alizé model, based French Pavement Design method, the thickness of the overlay
design criteria is, for a given risk of failure, the number of cycle before fatigue failure of the
base course. The number of cycle is related to the horizontal tensile strain at its base by the
fatigue curve of the material.
At a risk of failure of 10 %, 10 cm of the above design EME 0/16 is behaving like a GB 4 with
3 cm of the BBTM 0/11 will have a 13.4 years life expectancy with 25.5 millions of 100 kN
equivalent trucks. With the same hypothesis, the Polish base design (8 cm binder course
0/31) will have a life expectancy of only 4.5 years.
According to the French hypothesis, the estimation of the frost protection of this structure is
giving a frost index of only 190 °C. This value may be considered as low as corresponding to
the frost index of Strasbourg. A check of this structure according to the Polish frost design
method is recommended.
6. N 2 Job - first impressions
The experimental section is located on the N2 between Belowice and Lwowek and between
the km 119 450 and 120 500. This is a straight road without crossing with a plan profile. The
transversal profile was widened to 11.50 m before the overlay.
The overlay of the trial section is made of:
• Local plane out of the axis and of the rut shoulders

• 12 cm of the EME 0/16 with a emulsion tack coat
• 3 cm of the BBTM 0/11 en 3 cm for 500 m and of SMA for 500 m as reference for the
surface properties.
The reference structure is composed of 8 cm of a 0/31 base course mix with 3.5 to 4 %
binder content and 4 cm of SMA. Because of its high maximum stone size, the base course
shows a very open and heterogeneous aspect.
PRID Nowy Tomysl has laid the EME and BBTM respectively between the 28/08 and
04/09/2002 and from the 09 to 11/09/2002 under satisfactory weather conditions.
If the job has been carried according to the recommendations of the LCPC, the following
points can be improved:
• Regularity of aggregate production: they have presented too high grading variation (filler
content between 12 to 20 % in the sand where only 3 % is tolerated in France). The
formulation had to be recomposed in the mixing plant with inevitable variations on the mix
formula particularly for the BBTM.
• Tune up of the mixing plant: several adaptations of the parameters where required further
to the results of the hotmix quality control (this new mixing plant was indeed producing its
first tons of hotmix).
• Tune up of the paver: a test strip laid before the job would have allow a better laying and
avoid the evenness problem. The low quantities of material to lay (3500 t of EME and
420 t of BBTM) have complicated the job. Anyway, the low speed of the job limited by the
low throughput of mixing plant (90 t/h) has made possible a very good compaction.
• Stops of the mixing plant due to failures of the sand alimentation from to the abovementioned
excess of filler. They have caused stops of the paving with the consequence
of other evenness problems.
The above problems during the first application of a new technology with a new referential
are common. A period of practice is often required to take in account all the new parameters
and difficulties.
Thanks to the commitment of the crew, despite these incidents, the job has been carried in
relatively good conditions, which let us all hope that a representative behaviour of an
EME/BBTM structure can be followed up. These fluctuations should be anyway taken in
consideration while drawing conclusions of this road trial.
7. Conclusion
This co-operation between the Polish and the French road authorities has confirmed that
material, laboratory equipment and method are available to improve the functional
performance of hotmixes in Poland.
This job is the first opportunity to adjust
• for EME 2: the fatigue criteria and frost protection according to the Polish overlay
strategy ;
• for BBTM 1 (with sand patch between 0.8 and 1 mm) in comparison with the SMA: the
behaviour under winter condition of the high rugosity required for long lasting skid
resistance.
A follow up over at least 5 years is required to compare the behaviour of EME + BBTM
solution versus the conventional design. The main parameters to control are the surface
characteristics (macro texture and skid resistance) and the mechanical resistance (against
rutting and fatigue cracking) as well as behaviour under low temperature climate.

Facing increased traffic agressivity, it seems that the suggested solution can be developed
on the Polish main road network:
• within modernisation projects and structural reinforcement,
• whilst improving the safety for road users with better surface properties (no rutting,
texture, evenness).
8. Bibliography
1. French standard XP P98-137 - Enrobés hydrocarbonés - Couches de roulement : bétons
bitumineux très minces - Définition - Classification - Caractéristiques - Fabrication - Mise
en œuvre (05/2001)
2. French standard NF P98-140 - Enrobés hydrocarbonés - Couches d’assises : enrobés à
module élevé (EME) - Définition - Classification - Caractéristiques - Fabrication - Mise en
œuvre (11/1999)
3. French standard NF P98-138 Enrobés hydrocarbonés - Couches d'assises : gravesbitume
(GB) - Définition - Classification - Caractéristiques - Fabrication - Mise en oeuvre
(11/1999)
4. Very thin and ultra-thin wearing courses using hot-mixed bituminous materials - A review
of use and performance, Y. Brosseaud LCPC - Nantes – France in Cedex conference,
Madrid (1997)
5. Compared performance of very thin wearing courses using cold and hot mixed
bituminous materials - Assessment of French experience, Y. Brosseaud LCPC - Nantes -
France in 1st World conference on highway surfacing - Budapest, Hungary (1998)
6. Performance d’adhérence des revêtements sur les chaussées françaises, Y. Brosseaud
LCPC - Nantes - France, G. Delalande LRPC - Angers - France in Surf 2000 (AIPCR)
Nantes (2000)
7. The French approach to asphalt mixture design - a performance related system of
specification, JF. Corte (LCPC), JP. Serfass (SCREG) in TRB (2000)
8. Development and uses of hard grade asphalt and high modulus asphalt mixes in France,
JF. Corté (LCPC) in TRB (2001)
9. Investigation of rutting of asphalt surface layer: influence of binder and axle loading
configuration, JF. Corté, Y. Brosseaud, JP. Simoncelli, G. Carof (ASFA) in TRR n°1436
(p 28 -37) (1994)
10. Les Enrobés à Module Elevé, Note d’information du Setra n°96 (04/1997)
11. Les Bétons Bitumineux Très Minces et Ultra Minces, Note d’information du Setra n°94
(04/1997)
12. Guide d’application des normes pour le réseau routier national, SETRA LCPC (04/1994)
13. Guide technique de conception et de dimensionnement des structures de chaussée,
SETRA LCPC (09/1994)