Design and properties of polyurethane solid–solid phase-change granular temperature regulation asphalt mixtures

The application of phase change materials (PCMs) in asphalt pavement is one of the effective methods to adjust the pavement temperature. In this study, polyurethane-based solid–solid PCMs (PUSSPCMs) was synthesized by two-step solution polymerization, the asphalt mixtures using PUSSPCMs as fine aggregate were formed. The suitable particle size of PUSSPCMs was determined by the viscoelastic properties of asphalt mortars, the maximum content of PUSSPCMs was determined by the engineering performance of asphalt mixtures, and temperature regulation properties of asphalt mixtures was tested by self-designed experiment. It is demonstrates that the viscoelastic properties of PUSSPCMs-asphalt mortars was related to curing temperature, loading frequency, PUSSPCMs content and particle sizes. The elastic modulus of PUSSPCMs-asphalt mortars plays a leading role at low temperature, as the temperature increases, the viscosity modulus is dominant. The sample 2 # can absorb more light components in the asphalt and have greater interference on the viscoelasticity of the asphalt mortar, PUSSPCMs with 0.6–2.36 mm particle size is recommended. The high-temperature performance and low-temperature performance of 1–20 % asphalt mixtures increased by 26.2 % and 14.2 %, respectively. However, PUSSPCMs-asphalt mixtures show a worse water stability, and the residual stability of 1–30 % sample failed to meet the requirements. The heating rate of PUSSPCMs sample is always lower than that of the control samples during heating process, and the temperature difference between control sample and 1–20 %, 1–10 % samples is 4.6 ℃ and 3.3 ℃. In conclusion, the PUSSPCMs with 0.6–2.36 mm particle size, and volume replacement level with 20 % (1–20 % sample) is recommended to prepare temperature regulation asphalt pavement.