Evaluation of the apparent temperature-control contribution of solid-solid phase change materials to low-temperature crack resistance of asphalt

The temperature-control performance of low-temperature polyurethane solid-solid phase change materials (LPSP) can significantly improve the low-temperature performance of asphalt pavements. However, studies evaluating the low-temperature performance of LPSP-modified asphalt considering the temperature-control effect remain limited. Moreover, the quantitative contribution of the temperature-control effect to low-temperature performance improvement has not yet been clarified, and the relationship between temperature-control performance and low-temperature performance improvement remains to be further elucidated. In this study, the low-temperature performance of LPSP-modified asphalt considering the temperature-control effect was evaluated using dynamic mechanical analysis (DMA). A new method combining constant-temperature bending beam rheometer (BBR) and dynamic-cooling DMA tests was proposed to evaluate the apparent temperature-control contribution of LPSP to the improvement in low-temperature performance. The apparent temperature-control contribution rate was defined as (Δ T DMA − Δ T BBR )/Δ T DMA × 100%, where Δ T BBR and Δ T DMA denote the improvements in critical cracking temperature obtained from BBR and DMA tests, respectively. Computational fluid dynamics (CFD) was further employed to simulate the temperature-control performance of LPSP-modified asphalt and investigate its relationship with the resulting low-temperature performance improvement. The results indicate that the optimal low-temperature performance was achieved at a polytetramethylene ether glycol (PTMEG) mass fraction of 75%, a particle size of 30 mesh, and an LPSP content of 9 wt%. As the LPSP content increased from 1.5 wt% to 9 wt%, the apparent temperature-control contribution rate increased from 60.5% to 76.4%. Within the investigated PMA75 composition range, the temperature-control performance of LPSP-modified asphalt exhibited a strong linear correlation with the apparent improvement in critical cracking temperature (R² = 0.9907).