Performance and evaluation models for different structural types of asphalt mixture using shape-stabilized phase change material

The vulnerability of road infrastructure to changes in environmental conditions has received increasingly widespread attention. The ability to absorb and release latent heat using phase change material (PCM) can confer ability to store thermal energy in asphalt pavements. This mitigats the effects of environmental fluctuations on pavement performance. In this study, the influences of PPGC-PCM, a shape-stabilized phase change material, on the mechanical properties, moisture resistance, high temperature stability and low temperature crack resistance of different structural types of asphalt mixture (AC-13, SMA-13) were discussed. A test platform of unsteady thermal conductivity was established to analyze the effects of PPGC-PCM on the thermal conductivity and specific heat capacity of asphalt mixture with different structure types. An evaluation model was constructed using response surface methodology (RSM), and the impacts of PPGC-PCM and gradation type on the comprehensive performance of asphalt mixture were analyzed. The results showed that the addition of PPGC can improve the thermal insulation performance and heat storage efficiency of asphalt mixture. With the increase of PPGC-PCM addition, the mechanical properties and moisture resistance of the asphalt mixture first improved and then deteriorated. Compared with the control group, the Marshall stability and residual stability of the AC-13 and SMA-13 PPGC-PCM asphalt mixture could be improved by 3.7%, 3.3% and 6.7%, 7.5%, respectively. Addition of PPGC-PCM could obviously improve the insulation performance and heat storage efficiency of the asphalt mixture. The specific heat capacity of asphalt mixture increased significantly in the PPGC-PCM phase change temperature range. However, PPGC-PCM had negative effects on the long-term high-temperature stability and low-temperature cracking strength of asphalt mixture. For different structural types, the effect of PPGC-PCM addition on the mechanical and thermomechanical properties of asphalt mixtures was more pronounced as the continuity of gradation increased. Continuous-graded asphalt mixture can achieve better performance with lower PPGC-PCM addition, while gap-graded asphalt mixture can accommodate more PPGC-PCM particles and has better comprehensive performance. According to the performance evaluation model, the recommended additions of PPGC-PCM in AC-13 and SMA-13 asphalt mixture were 5.5%-8.5% and 7.5%-10.5%, respectively. Engineering application proved that when PPGC-PCM was added at 7.5% in asphalt pavement, the maximum temperature of the pavement in summer was reduced by 8.9 celcius with a time delay of 60 min compared to ordinary asphalt pavement. In winter, the experimental road section showed the potential to melt the snow more efficiently.