Identification of asphalt binder properties that affect cracking performance of hot mixed asphalt concrete pavements

Abstract

The overall objective of this study was to identify binder properties that affect cracking performance of hot mixed asphalt concrete (HMAC) pavements. In the late 1980s, test pavements were constructed in Texarkana and Sherman, Texas. In 1995, cores were obtained from these pavements and evaluated in the laboratory. Asphalt binders were comprised of both modified and unmodified AC-10 and AC-20 grade asphalt. Asphalt modifiers included latex, ethylene vinyl acetate, styrene-butadiene styrene-block (SBS) copolymer, SBS vulcanized with asphalt, manganese organic complex, polyethylene, and carbon black. Asphalt binders, retained during construction and sealed in cans, were tested using SUPERPAVE[] binder tests, dynamic shear rheometer (DSR), Fourier transform infrared (FT-IR), gel permeation chromatography (GPC), and asphaltene content (using heptane). Asphalt binders extracted from field cores were tested using FT-IR and GPC. Retained binders and aggregates were combined in accordance with the original mixture designs, compacted in the laboratory, and tested using the National Cooperative Highway Research Program (NCHRP) asphalt aggregate mixture analysis system (AAMAS) test protocols to assess relative resistance to fatigue cracking. Field cores were also tested using the NCHRP AAMAS test protocols. Susceptibility to fatigue cracking was related to low loss tangent values from DSR testing, high levels of oxidation as measured by FT-K high amounts of large molecular size (LMS) material from GPC testing, and high asphaltene contents. SUPERPAVE[] and AAMAS test results showed no correlation with the observed fatigue cracking.