Evaluation of the Thermal Behavior of Asphalt Mixtures Modified with Cement-Based Phase Change Composite

Phase change materials (PCMs) can absorb or release latent heat by changing their physical state within a certain temperature range, but directly added to the road, the mix can easily leak. Cement stone is an excellent encapsulation material, which can reduce the influence of PCMs on pavement performance. In this study, cement stones were used to encapsulate PCMs, and polyethylene glycol 6,000 and ethylene glycol distearate were used to prepare cement-based phase change aggregates (CPCAs). PCMs of 10% of total cement volume are directly mixed with cement to prepare CPCAs. The microstructure and thermal properties of PCM and cement indicate that cement and PCM form more stable composite materials through a hydration reaction. The initial weight loss temperature and enthalpy of polyethylene glycol 6,000-CPCAs are higher than those of ethylene glycol distearate-CPCAs. Moreover, the strength of polyethylene glycol 6,000-CPCAs is 1.4 times that of ethylene glycol distearate CPCAs; therefore, polyethylene glycol 6,000-CPCAs has better thermal and mechanical properties. The temperature of the top and bottom surface and the temperature difference of the phase change specimen were always smaller than those of the conventional asphalt mixture specimen, indicating a good effect on delaying the temperature increase. Compared with ordinary asphalt, phase change asphalt PCMs can effectively reduce pavement temperature, and asphalt binder can produce irreversible plastic deformation, which can improve the stability of asphalt pavements under high temperature conditions. The research results promote the application and development of PCMs in asphalt pavement construction system.