Laboratory evaluation of asphalt binder rutting, fracture, and adhesion tests.

PDFTech ReportFHWA/TX-14/0-6674-1Project 0-6674BindersRuttingPavement crackingPavement performanceLaboratory testsBituminous bindersAdhesionPerformance based specificationsMechanical analysisTexasTexas. Dept. of Transportation. Research and Technology Implementation OfficeZhou, FujieLi, HongshengChen, PeiruScullion, TomTexas A&M Transportation InstituteUnited States. Federal Highway AdministrationUS Transportation CollectionThe current performance grading (PG) specification for asphalt binders was developed based on the Strategic HighwayResearch Program (SHRP) and is based primarily on the study of unmodified asphalt binders. Over the years, experience hasproven that the PG grading system, while good for ensuring overall quality, fails in some cases to predict rutting and crackingperformance, particularly as it applies to softer but highly modified binders. Therefore, it is necessary to improve currentasphalt binder performance parameters and associated specification limits, especially for modified binders.This report documents the laboratory evaluation of several new tests for rutting, fatigue, and adhesion property of asphaltbinders, including the multiple stress creep and recovery (MSCR) test, linear amplitude sweep (LAS) test, double edgednotched tension (DENT) test, elastic recovery test, pull-off test, pneumatic adhesion tensile testing instrument (PATTI),dynamic mechanical analyzer (DMA) test, and surface energy test. It was found that the MSCR test and associatedspecification works better than the current G*/sin \uef?\ua4-based PG specification, especially for those highly modified asphalt binders(such as PG64-34). MSCR round robin results among five laboratories clearly indicated that both Jnr0.1 and Jnr3.2 results are veryrepeatable and reproducible, but both Jnrdiff and R0.1 have pretty high variability. Since Jnrdiff is one of the parameters for gradingasphalt binder, caution should be exercised when applying the MSCR specification. The R3.2 results are acceptable in terms ofrepeatability and reproducibility. Based on the laboratory test results, users should exercise some caution when grading theslightly modified asphalt binders (such as PG64-28) using the MSCR test and associated specification. This study furtherconfirms the poor relationship between the parameter G*sin\uce\ub4 and the binder fatigue resistance. Neither the MSCR nor theelastic recovery test shows good correlation with the asphalt mix OT cracking test. Both the LAST and the DENT tests providesimilar ranking to that of asphalt mix OT cracking test. The DSR-based LAS test is recommended for asphalt binder fracturetest, since the DSR has been widely used in the last 20 years. Additionally, only the PATTI test is a promising test forevaluating adhesive properties of asphalt binders. All three other tests (the pull-off test, DMA, and surface energy test) werenot successful in this study for evaluating asphalt binder adhesion property.Obviously, these laboratory findings need further field validation. Additionally, one needs always to keep in mind that thebinder alone does not determine field performance of asphalt mixes. Mix characteristics as well as the pavement structure itself,traffic, and the environment within which it is located have a significant role in determining pavement performance