Evaluation of Strain Recovery and Stress Sensitivity of Asphalt Binders Containing Warm-Mix Asphalt Additive and Anti-stripping Agent

This study was undertaken to evaluate the effect of Warm-Mix Asphalt (WMA) additives and Anti-Stripping Agents (ASA) on strain recovery capability and stress-sensitivity of asphalt binders. For this purpose, a PG 58-28 asphalt binder, two different WMA additives, and two different ASAs were collected from local suppliers in Oklahoma. The amount of WMA additives and ASA were kept constant. The Multiple-Stress Creep and Recovery (MSCR) test were conducted on the RTFO-aged binder blends using a dynamic shear rheometer. To evaluate the stress sensitivity, the RTFO-aged binder blends were subjected to a higher stress level of 10 kPa, in addition to 0.1 kPa and 3.2 kPa stress levels. It was found that none of the selected additives affected the complex modulus or the strain recovery capability of the binder blends significantly. The non-recoverable creep compliance of binder blends containing WMA additives or ASA was similar to that of the base binder. As a result, asphalt mixes containing WMA additives or ASAs are expected to sustain approximately the same level of traffic (standard traffic loads with less than 10 million ESAL traveling at more than 45 MPH).