Developing a solid–solid phase change heat storage asphalt pavement material and its application as functional filler for cooling asphalt pavement

Currently, functional pavement materials become a research hotpot for road researchers. This paper aims to develop a phase change heat storage asphalt pavement material and then design phase change heat storage asphalt mixtures with active cooling ability. The synthesized polyurethane-based solid–solid phase change material (PUSSPCM) with suitable phase change temperatures, desirable thermal energy storage capacity and excellent phase change cycling stability can meet the active cooling demand of asphalt pavement. There are also excellent leakage resistance, volume stability and chemical stability that enable withstanding the harsh condition of asphalt pavement. Therefore, the PUSSPCM can be considered as a promising phase change filler. Subsequently, the phase change heat storage asphalt mixtures are prepared by the equal volume replacements of limestone filler with PUSSPCM. The replacements can improve the high-temperature stability and low-temperature cracking resistance whereas weaken the water stability of an asphalt mixture. When the replacement amount is no more than 40 vol%, the phase change mixtures can satisfy the pavement performance requirements. The replacements increase the heat absorption capacity but decrease the heat transfer rate, which leads to decrease in the temperature rising rate of the asphalt mixture with more PUSSPCM.