Study on preparation and thermal performance improvements of composite phase change material for asphalt steel bridge deck

•Exploring the thermal performance of phase change asphalt mixture.•Equal volume replacement of mineral filler and fine aggregate with CPCMs.•Exploring the mechanical strength of phase change asphalt mixture. Phase change materials (PCMs) have the capabilities of thermal energy storage and temperature regulation. However, the application of PCMs in asphalt pavements is still limited due to the severe leakage and low thermal performance problem. In this research work, the phase change asphalt mixture (PCAM) with Polyethylene glycol/hydrophobic fumed silica composite phase change material (PEG/HFS) and Polyethylene glycol/SiO2 composite phase change material (PEG/SiO2) replacing mineral filler and fine aggregate was prepared and tested. The leakage experiment illustrated that the PEG/HFS with PEG content of 45% (wt) and PEG/SiO2 with PEG content of 70% (wt) had good thermal exudation stability. The results of XRD and FTIR showed that the preparation process of composite phase change materials (CPCMs) was a pure physical mixing process without chemical reactions. In addition, based on the results of the indoor radiation test, Marshall test, and rutting test, we found that when mineral filler and fine aggregate were replaced by 25% of the same volume of CPCMs, the PCAM exhibited a better cooling effect and relatively small decrease in mechanical strength. Therefore, the PCAM developed in this research has great potential for improving the thermal performance of asphalt steel bridge deck.