Moisture Susceptibility of Asphalt Mixtures: Thermodynamic Evaluation of the Effects of Antistripping Additives

Abstract

The intrusion of moisture into asphalt pavements affects the cohesion and adhesion properties, which in turn, can lead to several durability- and integrity-related problems, such as potholes and stripping, as well as several types of other distresses, such as fatigue cracking and rutting. The use of antistripping additives is one of the most commonly used techniques to enhance the resistance of asphalt pavements to moisture damage. In this research, the effects of five different types of antistripping additives (i.e., Zycotherm, WETMUL-950, GRIPPER L, Evonik, and TeraGrip) on the moisture resistance of asphalt pavements were evaluated and compared with each other. For this purpose, two series of experimental methods were used: (1) the surface free energy (SFE) to evaluate the adhesion and cohesion properties of the asphalt binders and aggregates, and (2) the indirect tensile stress (ITS) and resilient modulus tests to investigate the moisture susceptibility of asphalt mixtures. The results of the laboratory evaluation showed that all the additives used in this study improved the adhesion and cohesion properties and increased the resistance of the asphalt mixtures to moisture susceptibility. The asphalt mixtures containing Zycotherm and WETMUL-950 showed the highest resistance to moisture damage among all the additives studied in this research.