3 - Performance of thermochromic asphalt

Abstract

Asphalt pavements are commonly applied to highways due to their low construction cost and rheological and mechanical properties (i.e., ductility, self-healing, and load capacity). However, the black color causes absorption of solar radiation, which creates high pavement temperatures, contributing to thermal oxidation and photooxidation. Asphalt binder is susceptible to temperature, becoming soft when heated and stiff when cooled, leading to rutting in summer and cracking in winter. Thermochromic materials can reversibly change their solar reflectance in accordance with temperature. They can be designed to have high solar reflectance at high temperature and low solar reflectance at low temperature, enabling them to be applied to adjust the temperature of asphalt pavement. Additionally, studies have proven that thermochromic powders can reduce the rutting and low-temperature cracking in asphalt pavements and provide an antiaging property in asphalt binders. This chapter first introduces three-component organic reversible thermochromic microcapsules, including their classification, merits, components, microstructure, thermochromic mechanism, and thermal and optical properties. Then, the performance of thermochromic asphalt binders is illustrated as related to optical, thermal, rheological, and antiaging properties, including the adjustment of thermochromic asphalt temperature. Finally, some proposals on future research on thermochromic asphalt are discussed.