Improved Life for Longitudinal Joints in Asphalt Pavement - WisDOT ...

WisDOT ApproachThe current WisDOT design of longitudinal joints in asphalt pavement is a “Michigan joint” or “wedge joint”design. It features a ½-inch notch at the top of the joint, a vertical drop perpendicular to the lane surface, and a 12:1tapered slope into the space where the next lane will be laid. This joint is treated with a tack coat and the next layeris rolled over the joint slope. If the joint is cold, it is heated and tacked and the next lane is placed. See WisDOTStandard Specifications, Sections 450.3.2.5(6) and 450.3.2.8, athttp://roadwaystandards.dot.wi.gov/standards/stndspec/sect450.pdf (pages 5 to 6 of the PDF). For a drawing, see theWisDOT Facilities Development Manual, Chapter 14, Procedure 14-10-5, Figure 5, athttp://roadwaystandards.dot.wi.gov/standards/fdm/14/FDM14.pdf (page 29 of the PDF).Joint DesignThe Michigan or tapered joint became the standard in the 1990s. A variety of publications have spun off NCATReport No. 97-4, published in 1997, which formally established the effectiveness of the tapered or notched joint.National Center for Asphalt Technology. Since at least the late 1990s, the Michigan or tapered joint design hasbeen considered the best option for longitudinal joints in asphalt pavements and asphalt overlays. An NCAT studycompared joints in Michigan, Wisconsin, Colorado and Pennsylvania, and the results led to a number of later articlesand studies. These include:• Longitudinal Joint Construction Techniques for Asphalt Pavements, Prithvi Kandhal and Rajib Mallick,NCAT Report No. 97-4, August 1997.http://ntl.bts.gov/lib/7000/7900/7944/rep97-4.pdfThis project studied 30 designs in four states. The best-performing joint after four years was a Michiganjoint that featured a 12.5-mm vertical offset and a 12:1 taper.• A 2007 NCAT PowerPoint presentation includes material from the 1997 study (seehttp://www.ucs.iastate.edu/mnet/_repository/2007/asphalt/pdf/practices%20and%20specifications%20for%20longitudinal%20joints%20-%20prowell.pdf). The presentation discusses measuring performance at thetime of construction, describes German methods, and presents four states’ specifications. Best-performingmethods for construction include:o Use of rubberized joint adhesiveo Notched-wedge design, with a 12:1 taper over 12 inches, and a notch of 0.5 to 0.75 incheso Use of cutting wheel and edge-restraining deviceo Rolling from hot side with 6-inch overlap• A PowerPoint presentation on the NCAT data confirms the Michigan joint’s effectiveness, and notesseveral factors in effective joint construction (seehttp://www.asphaltalliance.com/upload/Longitudinal%20Joints%20-%20Ray%20Brown.pdf). Conclusionsinclude:o Vertical offsets are essential.o Rubberized joint adhesive is effective.o Rolling should be conducted as soon as possible.o The joint can be compacted to a density within 2 percent of the mat density.• See also “Study of Longitudinal-Joint Construction Techniques in Hot-Mix Asphalt Pavements,” PrithviKandhal and Rajib Mallick, Transportation Research Record No. 1543, 1996: 106-112. (See attached file.)• The “New Jersey” joint, one of the other designs tried and found less effective, is a 3:1 wedge without anotch at the unconfined edge of the first lane that is heated before the next lane is placed.• “Asphalt Answers,” Roads and Bridges Magazine, January 1998.http://www.roadsbridges.com/ASPHALT-ANSWERS-article973Kandhal writes that after five years, the Michigan joint remains the most promising design.TRB“Evaluation of Notched-Wedge Longitudinal Joint Construction,” M. Shane Buchanan, Transportation ResearchRecord No. 1712, 2000: 50-57. (See attached file.)This paper, from the 2000 TRB Annual Meeting, follows up on notched-wedge joints in Alabama, Colorado,Indiana, Maryland and Wisconsin, and finds from cores that they’ve been performing well in terms of density at thelongitudinal joint.2

Compaction and DensityProper density and compaction at the longitudinal joint present difficulties to construction crews. For the first pavedlane, roller passes push material out, resulting in reduced density at the edge. In paving a second lane, with aconfined edge at the first, proper compaction at the joint can be hampered by cooling of the HMA. Many of thereports below focus on the effectiveness of a density or permeability specification—in some cases with incentives ordisincentives to force contractor compliance. The following research and documents focus on density andcompaction of longitudinal joints in terms of construction, specifications, quality and performance.NCHRP. Project 9-15, “Quality Characteristics and Test Methods for Use in Performance-Related Specifications ofHot Mix Asphalt Pavements,” completed June 2004.http://www.trb.org/trbnet/projectdisplay.asp?projectid=951Phase I identified construction-based performance characteristics of HMA pavements that warrant testing for qualityassurance, and distilled these to five characteristics for testing; longitudinal joint density was one of these. Phase IItested these qualities with available methods to determine best methods and quality standards.For a detailed summary of findings, see Research Results Digest 291, August 2004, athttp://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rrd_291.pdf. The digest addresses longitudinal joint density onpages 5-6. Research compared density readings from a pavement quality indicator, a nuclear gauge, and frompavement cores, finding PQI results the most accurate. Based on PQI readings, investigators categorized jointdensity relative to lane or mat density in three classifications as a guideline for specifications:• Good density at the joint measures greater than 97 percent of mat density.• Fair density at the joint measures 93 to 97 percent.• Poor density at the joint measures less than 93 percent.KentuckyCompaction at the Longitudinal Construction Joint in Asphalt Pavements, L. John Fleckenstein, David Allen andDavid Schultz Jr., March 2002.http://www.ktc.uky.edu/Reports/KTC_02_10_SPR200_00_1F.pdfInvestigators tracked joint construction at 12 pavement sites during construction, evaluating the density achieved onthe longitudinal joints. Four construction approaches were used, including building notched-wedge (12:1) joints aswell as using a restrained edge, a joint re-heater and a Joint Maker. All joints were performing well afterconstruction. Those that employed joint adhesives were performing as well as or better than those that did not,leading investigators to recommend the use of joint adhesives.TRBFactors Affecting Compaction of Asphalt Pavements, Transportation Research Circular E-C105, September 2006.http://onlinepubs.trb.org/onlinepubs/circulars/ec105.pdfThis e-circular includes four articles on longitudinal joint construction, beginning on page 85 of the PDF. Topicsinclude compaction, voids, measuring density at joints, and durable joint construction. Important factors in buildingdurable joints include:• Proper compaction of the unsupported edge of the first lane placed.• Ensuring that overlap of asphalt from the second lane placed is about 1 to 1.5 inches to ensure enoughmixture in the new lane for a properly compacted lift and to prevent a depression between lanes. Overlapon the first lane must be shoveled off the pavement, not raked into the new lane.• Placing the mixture precisely enough to avoid raking at the joint.• Compacting the joint from the warm pavement lane, not the cold, and allowing the roller to extend no morethan 6 inches over the cold lane.Construction and SpecificationsThe following activities focus on construction techniques and activities, as well as on the development andeffectiveness of a density specification for longitudinal joints.KansasLongitudinal Joint Construction for Hot Mix Asphalt Pavements, M.V. Akpinar and M. Hossain, March 2004.http://www.ksdot.org/idmws/DocContent.dll?Library=PublicDocs^dt00mx38&ID=003686991&Page=1This literature search explores density problems at the longitudinal joint, including construction techniques andspecifications from various studies.3

Maine“Longitudinal Joint Study,” Federal Experimental Report 96-2, September 2001.http://mainegov-images.informe.org/mdot/transportation-research/pdf/report9602f.pdfThis five-year study of longitudinal joints constructed in 1996 evaluated various methods of longitudinal jointconstruction during rolling of HMA pavement. Joint-making equipment, rolling patterns, edge trimming and othertechniques were evaluated in various combinations. The best performance was in the section in which rolling wasconducted from the cold mat with a 6-inch overlap into the hot mat; this method is the reverse of the recommendedmethod by NCAT and other studies.New Hampshire“Field Trial of Infrared Joint Heater to Improve Longitudinal Joint Performance in New Hampshire,” Jo Sias Daniel,University of New Hampshire, and William Real, NHDOT; Transportation Research Record No. 1946, 2006: 157-162. (See attached file.)This field study evaluated the use of infrared joint heaters to improve longitudinal joint performance. The heateressentially affects only the top layer of the full-depth asphalt structure, suggesting potential for using this methodwith overlays.Ontario“Longitudinal Joint Compaction: Improving Paved Lanes,” Road Talk, Vol. 10 (2), May 2004.http://www.mto.gov.on.ca/english/transtek/roadtalk/rt10-2/index.html#jointThe Ontario Ministry of Transportation evaluated the use of incentives and testing of density at joints to ensure thatjoints were constructed as specified. Investigators evaluated the long-term performance of four trial sections pavedin 1997 in which compaction was tested at the longitudinal joints to ensure contractor compliance, not a requirementat the time. Trials included both standard and unconventional methods and equipment. Highlights include:• Four methods were evaluated, including standard paving and compaction, use of a joint heater, use of ajoint-building system with a compactor and kicker-plates as well as an electronic monitoring device, anduse of both a heater and the jointing and monitoring system.• No method proved superior to the others, but all achieved compaction rates of 95 percent or greater.• After four years and after six years, joints were in excellent condition.• Contractor performance has been encouraged through bonuses for meeting standards on 95 percent or moreof examined edges, and penalties for meeting standards at 90 percent or less of examined edge points.PennsylvaniaEvaluation of Eight Longitudinal Joint Construction Techniques for Asphalt Pavements in Pennsylvania, PrithviKandhal, Timothy Ramirez and Paul Ingram, NCAT Report No. 2002-03, February 2002.http://www.eng.auburn.edu/center/ncat/reports/rep02-03.pdfFollowing up on some of the sites included in the 1997 NCAT study, researchers evaluated the six-year performanceof the eight techniques used in Pennsylvania in 1995. Findings included:• Joints using rubberized joint material had performed best.• The joint constructed using a cutting wheel was a close second.• Sections on which rolling from the hot side away from the joint was used performed reasonably well.• The New Jersey wedge joint performed reasonably well.TexasDensity Evaluation of the Longitudinal Construction Joint of Hot-Mix Asphalt Pavements, Cindy Estakhri, ThomasFreeman and Clifford Spiegelman, Texas Transportation Institute: April 2001.http://tti.tamu.edu/documents/1757-1.pdfThis Texas study of density in longitudinal joints in HMA evaluated joints at 35 sites, considered airfield andpavement regulations, and conducted laboratory tests. One of the study’s goals was to identify the viability of adensity specification for longitudinal joints in asphalt pavement, and investigators developed and proposed aspecification. Findings include:• Some states and the Federal Aviation Administration maintain a density specification for longitudinal jointsin asphalt, and contractors have little trouble meeting the requirement.• Density was always lower at the unconfined edge of the pavement than at the middle of the lane. Thedifference averaged about 4 to 5 percent, about 6 to 7 pounds per cubic foot.• The proposed specification would require the difference to be kept to 5 pounds per cubic foot.4

Washington State“Longitudinal Joint Construction Techniques,” Washington State DOT Tech Notes, February 2003.http://www.wsdot.wa.gov/biz/mats/Pavement/TechNotes/LongitudinalJointConstruction.PDFThis construction primer draws heavily on the Pennsylvania study, NCAT Report No. 2002-03 above.Recommendations and observations include:• Notched-wedge joints outperform joints with no notch, including the New Jersey joint.• Whatever joint design is used, roll from the hot mat side.• Rubberized sealants perform well.• Specify density within 2 percent of the mat density.• Follow the NCAT recommendation that there be no more than 10 percent air voids.Contact: Jeff Uhlmeyer, (360) 709-5485, uhlmeyj@wsdot.wa.gov.SealantsThe following documents pertain to the performance of joint sealants in mitigating or preventing longitudinal jointfailures.IllinoisInterim Report: Experimental Joint Sealants for Hot Mix Asphalt Pavements and Overlays, In-House Report No.I2004-07, October 2004.http://www.dot.state.il.us/materials/research/i2004-07.pdfThis research focused on construction and testing of sealants for longitudinal joints at two Interstate sites and twostate highway sites in 2003. At two of the four project sites, sealants were ineffective at reducing permeability; at theother two, the sealants had some impact but were still sticky enough to adhere to the tires of passing vehicles. J-Band was easy to place, while QuickSeam was difficult.The study is expected to conclude in 2009; see the TRB Research in Progress entry athttp://rip.trb.org/browse/dproject.asp?n=13344.Contacts: Aaron Toliver, Principal Investigator, (217) 782-0564, aaron.t.toliver@illinois.gov. LaDonna Rowden,Bureau of Materials and Physical Research, (217) 782-8582, LaDonna.Rowden@illinois.gov.Video: Evaluation of Longitudinal Joint Sealant, Illinois Department of Transportation, 2003.http://www.state.il.us/video/streaming/idot/V181.asxThis video demonstrates research and use of two sealants designed to reduce longitudinal joint damage.MaineLongitudinal Joint Treatment, Final Report, Technical Report 00-18, March 2006.http://mainegov-images.informe.org/mdot/transportation-research/pdf/report0018final.pdfThis study evaluated three joint sealants over a six-year period to test their performance in preventing jointseparation. All joints performed well, and inspection did not find any significant difference in performance betweenthe three sealants.New York“Constructability of Longitudinal Construction Joints in Hot-Mix Asphalt Pavements with Sealers to Retard FutureDeterioration,” Edward Denehy, Transportation Research Circular E-C078: Roadway Pavement Preservation,2005, October 2005.http://www.trb.org/publications/circulars/ec078.pdf (pages 16 to 23 of the PDF)Sealants were used in longitudinal joint construction of notched-wedge joints in Pennsylvania, and NYSDOTinvestigated the constructability of using adhesives during paving in the summer of 2004 by having three contractorsconstruct HMA pilot projects, each with a different sealant. Sealant use had no negative effect on paving activitiesor compaction.5

Quality ControlThe following research focuses on the use of field permeameters for quality-control monitoring of longitudinaljoints.New England Transportation ConsortiumProject 03-5, Evaluation of a Field Permeameter as a Longitudinal Joint Quality Indicator, Jo Sias Daniel, RajibMallick and Walaa Mogawer, University of New Hampshire, April 2007.http://www.netc.umassd.edu/netc03_5_final_report.pdfThis study sought to evaluate the use of field permeameters for evaluating the quality of constructed longitudinaljoints. Various construction methods were used, including the use of infrared heaters and joint sealants. Based ondensity, air void content and strength from cores, conclusions included:• Permeameter use is promising but requires refinement to reduce variability.• Joint sealants and joint heaters improve short-term joint performance.See also “Development and Evaluation of a Field Permeameter as a Longitudinal Joint Quality Indicator,” R.B.Mallick and J. Daniel, International Journal of Pavement Engineering, Vol. 7 (1), March 2006: 11-21. View theabstract at http://www.informaworld.com/smpp/content~content=a741577671~db=all~order=page.Research in ProgressFive ongoing projects pertain to longitudinal joint characteristics and construction.Arkansas“HMA Longitudinal Joint Evaluation and Construction,” expected completion date June 2009.http://rip.trb.org/browse/dproject.asp?n=13587Arkansas is evaluating the use of a density specification for quality control.Contacts: Mark Greenwood, Project Manager, (501) 569-2552, mark.greenwood@arkansashighways.com. StacyWilliams, Principal Investigator, (479) 575-2220, sgwill@engr.uark.edu.Colorado“Evaluation of Longitudinal Joint Density,” expected completion date December 2010.http://rip.trb.org/browse/dproject.asp?n=9807Investigators are comparing the longitudinal joint density of seven asphalt pavement projects constructed in 2004under a density specification to seven projects constructed in 2000 without such a specification.Contacts: Roberto de Dios, Project Manager, (303) 757-9975, roberto.dedios@dot.state.co.us. David Weld,Principal Investigator, (425) 284-3820, david@inrix.com.Illinois“Experimental Feature: Evaluating Longitudinal Joint Compaction Techniques,” no expected completion date given.http://rip.trb.org/browse/dproject.asp?n=5482This project is evaluating longitudinal joint construction techniques, specifications and elimination of pneumaticrollers.Contact: Tessa Volle, Principal Investigator, (217) 782-3547, volleth@nt.dot.state.il.us.Oklahoma“Longitudinal Joint Density and Permeability in Asphalt Concrete,” expected completion date 2008.http://rip.trb.org/browse/dproject.asp?n=12547Oklahoma does not have a density specification; this study will use field and laboratory methods to develop a testmethod and a specification for ensuring optimal density and permeability of longitudinal joints. Also see the FFY07Problem Statement at http://www.okladot.state.ok.us/hqdiv/p-r-div/spr-statements/pdfs/statements.pdf (page 5 of thePDF).Contact: Stephen Cross, Principal Investigator, (785) 864-4290, sac@kuhub.ccukans.edu.6

Tennessee“Evaluation of Longitudinal Joints of HMA Pavements in Tennessee,” expected completion date July 2008.http://rip.trb.org/browse/dproject.asp?n=15419Tennessee investigators believe longitudinal joint failures may be related to compaction difficulties due totemperature differences between lanes, and the ineffectiveness of adhesives under such conditions.7