Performance of Dopamine-Nano-Modified Antistripping Asphalt and Its Mixes

Water damage can significantly impact the performance and structural integrity of asphalt pavements, ultimately reducing their service life. Enhancing asphalt–aggregate adhesion is crucial in mitigating water damage. This study developed a composite antistripping agent containing dopamine methacrylamide (DMA) and nanomaterials [nano-silicon dioxide (nano- SiO 2 ) or nano-calcium carbonate (nano- CaCO 3 )] to improve the antistripping performance of asphalt and its mixes. Two nano-modified asphalts, nano- SiO 2 -modified asphalt (NSA) and nano- CaCO 3 -modified asphalt (NCA), and two DMA-nano-modified asphalts, DMA-nano- SiO 2 -modified asphalt (DNSA) and DMA-nano- CaCO 3 -modified asphalt (DNCA), were prepared using a high-speed shearing process. The 70-pen asphalt (VA-70) was used as a benchmark, and the water stability, high-temperature stability, and low-temperature cracking resistance of the four asphalts and their mixes were evaluated and compared. The results show that both nanomaterials and DMA in combination with nanomaterials enhance water stability and high-temperature performance. DMA and nano- SiO 2 improved low-temperature cracking resistance, while DMA and nano- CaCO 3 or single nanomaterial doping led to a decrease in performance. DNSA and DNCA, as well as their mixes, outperformed NSA and NCA, with DNSA showing the best water stability and superior performance at both high and low temperatures. Compared with VA-70, the reductions in stripping ratios for NSA, NCA, DNSA, and DNCA were approximately 40%, 38%, 61%, and 49%, respectively. Improvements in residual stability were 5%, 8%, 15%, and 11%; tensile strength ratio (TSR) improvements were 4%, 6%, 14%, and 9%; and shear strength increased by 9%, 11%, 29%, and 25%. The tensile failure strains of NSA, NCA, and DNCA decreased by about 1%, 4%, and 1%, while that of DNSA increased by 7%. Furthermore, NSA, NCA, DNSA, and DNCA improved the adhesion between asphalt and granite aggregates more effectively than with limestone aggregates.