Effect of Anti-stripping Agents on Asphalt Mix Performance Using a Mechanistic Approach

Abstract

Anti-Stripping Agents (ASAs) are widely used by the asphalt industry to improve the resistance of asphalt mixes to moisture-induced damage. The effectiveness of an ASA largely depends on its type, asphalt binder type and source, binder content, and aggregate type. This study was undertaken to evaluate the effects of two types of ASA on the rheology, Superpave® Performance Grade (PG) and moisture-induced damage potential of a PG 58-28 asphalt binder. For this purpose, the asphalt binder was blended with 0.5% of two different types of ASA using a high shear mixer. Surface Free Energy (SFE) components of the binder blends were determined and used to evaluate work of adhesion, work of debonding and energy ratio values of the asphalt-aggregate (limestone and granite) systems to assess their moisture-induced damage potential. It was found that incorporation of the ASA in the binder slightly increased the rutting resistance. However, no significant changes in the dynamic viscosity were observed as a result of adding ASA to the binder. The SFE results revealed that adding both types of ASA to the binder improved the bonding between the binder and a granite aggregate, indicating a reduced moisture-induced damage potential, as expected. The moisture-induced damage potential of the PG 58-28 binder with a limestone aggregate was found to reduce by using an amine-based ASA. The findings of this study demonstrate that the SFE-based approach is an effective tool for the assessment of moisture-induced damage potential of asphalt mixes.