Quantitative optimization of the cooling performance of thermal-reflective coating on asphalt pavements

Asphalt pavements are generally more susceptible to rutting under high temperatures, which can be further exacerbated by prolonged solar exposure and thermal absorption. The continuous thermal radiation from the asphalt pavement could aggravate the urban heat island effect and negatively impact urban life. To address this problem, this study was conducted to develop and evaluate a thermal-reflective coating material that minimizes thermal absorption and enhances the cooling effects of asphalt pavements. As documented herein, three pigment fillers were comparatively assessed in terms of their ability to enhance thermal reflectance, namely Hollow Glass Beads (HGB), Rutile Titanium Dioxide (RTD), and Potassium Titanate Whiskers (PTW). Acrylic resin (AR) and epoxy resin (ER) served as the base binding materials, while Polyamide acted as the curing agent. The performance of these materials was analyzed through various tests, including tensile strength, indoor cooling simulation, outdoor (field) cooling, and Differential Scanning Calorimetry (DSC)measurements. The corresponding results indicated that the optimum composition for the coating materials consist of: (1) base materials (namely 50% AR and 50% ER); (2) pigment fillers (namely 25% HGB, 20% RTD, and 15% PTW); and (3) curing agent (namely 40% Polyamide), with 2 mm as the optimum coating thickness to minimize thermal absorption.