Moisture Damage Resistance of GTR-Modified Asphalt Binders Containing WMA Additives Using the Surface Free Energy Approach

Abstract

The present study was undertaken to understand the moisture damage resistance of unmodified and ground tire rubber (GTR)–modified asphalt binders containing three different type of warm mix asphalt (WMA) additives using the surface free energy (SFE) approach. The SFE parameters of unmodified and GTR-modified asphalt binders with and without WMA additives were determined in the laboratory using the Wilhelmy plate method. The SFE of two types of aggregate, namely, granite and limestone, were adopted from literature. Thereafter, work of adhesion, work of cohesion, work of debonding, and energy ratio (ER) were estimated for a total of 16 different combinations of aggregate and asphalt binder. An attempt was made to evaluate sensitivity of SFE parameters with elemental composition (carbon, hydrogen, nitrogen, and sulfur) of asphalt binder. The results showed that moisture damage resistance of unmodified and GTR-modified asphalt binder decreases with addition of WMA additives. The control asphalt binder with Rediset (Akzo Nobel, Netherlands) showed better bond with aggregate, followed by Sasobit (SasolWax, Hamburg, Germany) and Advera (PQ Corporation, Malvern, Pennsylvania). The limestone aggregate showed better moisture damage resistance compared with granite aggregate. The elemental composition (CHNS) of an asphalt binder found to have a fair correlation with SFE parameters.