Laboratory Evaluation of the Relationship of Asphalt Binder and Asphalt Mastic via a Modified MSCR Test

Asphalt mastic, which consists of an asphalt binder and a mineral filler, provides critical adhesion and viscoelasticity to an asphalt mixture. The rheological response of the asphalt mastic is mainly derived from its asphalt binder. In this study, a simple laboratory test method is proposed to estimate the relationship of asphalt binder and its mastic. Two modified binders (3.5% and 4.0% styrene–butadiene–styrene (SBS) of asphalt binder by mass) were blended with a limestone filler at six different mineral filler contents to produce mastic samples. A modified multiple stress creep-recovery (MSCR) test was conducted on both the asphalt binder and its mastic with the same testing protocols, and the stress conditions and rheological response of asphalt binder in the mastic with linear or nonlinear viscoelasticity were both investigated. The results show that the stress of the asphalt binder in its mastic decreased with increasing filler contents. However, for the linear-viscoelasticity mastic, the decrease rate of the stress began to slow down when the filler content had reached 100% or 120%. For the rheological properties of the asphalt binder in the mastic, the %R of the asphalt binder was improved by adding filler, especially for the nonlinear-viscoelasticity mastic. The asphalt binder of the linear-viscoelasticity asphalt mastic also showed a linear viscoelastic response and a good recovery property. The performance of the asphalt mastic and rheological properties of its asphalt binder were highly related to its filler content.