Mechanism and Effectiveness of a Silicone-Based Warm Mix Additive

Abstract

Water damage is a major obstacle to the development of warm mix asphalt (WMA) technology. The addition of antistripping agents (ASAs) increases the difficulty of construction, and it may interact with warm mix additives, resulting in the uncertainty of long-term performance of asphalt mixture. In this paper, a silicone-based warm mix additive with adhesion promoting properties with the proprietary name TEGO, was studied. The warm mixing mechanism of the additive and the effect on asphalt-aggregate interface adhesion was mainly studied. The rotational viscosity (RV) of the asphalt binder and asphalt mortar with different dosages of TEGO at different temperatures was investigated based on the RV test to evaluate the warm mixing efficiency of each component in TEGO from two levels, the binder and the mortar. The infrared (IR) spectrum of asphalt binder before and after modification with TEGO and the two aggregates before and after treatment with TEGO was tested to evaluate the microcosmic mechanism of the additive in the asphalt mixture system. The concept of surface free energy (SFE) and the corresponding indexes [work of cohesion of asphalt, work of adhesion between asphalt and aggregate, and spreading coefficient (Sa/b)] was tested to evaluate the workability and water damage resistance of the mixture comprehensively. The results showed that the warm mixing mechanism of TEGO mainly includes viscosity reduction, interfacial lubrication, and improvement of wettability of asphalt to aggregate. TEGO can form a good physical combination with aggregates and it enhances the bonding potential of asphalt with aggregates.