Study on the crack resistance of USP warm-mix rubber asphalt and its mixtures

This study addresses the high mixing temperatures, high viscosity, and low-temperature cracking of rubber-modified asphalt (AR) and evaluates the modification performance of a domestically developed USP warm-mix technology. USPA-R and USPA-C2 are used to prepare warm-mix rubberized asphalt, and corresponding mixtures are designed with AC-13 and SMA-13 gradations. Penetration, softening point, ductility, viscosity, BBR, DDT, fluorescence analysis, and three-point bending tests are conducted in accordance with relevant standards, and ABAQUS simulations are integrated to elucidate mechanisms and quantify performance responses. The results show that both warm-mix additives improve the conventional properties and low-temperature deformation resistance of asphalt concrete (AC), with USPA-C2 exhibiting superior performance. In three-point bending, AC-13 generally outperforms SMA-13; relative to AC-R, USPA-C2 increases the maximum flexural strain by approximately 252 µε, whereas USPA-R yields an increase of about 142 µε. When fibers are incorporated, crack resistance is further enhanced, with basalt fiber providing the greatest benefit (≈ 16.8% improvement at - 10 °C). Mechanistically, the warm-mix agents are understood to promote binder mobility and energy dissipation by modulating asphalt-fraction distribution and intermolecular interactions. Overall, low-temperature crack resistance is substantially increased while required construction temperatures are reduced, thereby extending service life, decreasing curing demands, and delivering energy-saving and emission-reduction benefits.