Aging Resistance Index and Experimental Study of Warm Mix Asphalt Modified by Mastic Powder and Nano-TiO₂

In order to study the rheological properties and evaluation indexes of aging performance of mastic powder and nano-TiO₂ composite modified warm mix asphalt under aging conditions, and to evaluate the utility of composite modified materials on asphalt aging performance improvement, the viscosity aging index, complex modulus aging index, rutting factor aging index, and complex modulus index were used to evaluate the aging resistance of mastic powder and nano-TiO₂ composite modified warm mix asphalt. The test results showed that Sasobit inhibited the aging and decay of rubber (CR) particles, thus increasing the viscosity aging index of rubber-modified asphalt (CRMA). After PAV aging, the order of complex modulus aging index (AR) values remains unchanged, but the magnitude of change becomes larger. The results indicated that the rubber powder could improve the thermal and oxygen aging resistance of 70#, but Sasobit on CRMA60-22%. Both anti-oxidation and long-term aging resistance had negative effects, while nano-TiO₂ can effectively improve the anti-aging performance of CRMA60-22%-2.5% Sasobit. With the deepening of aging, the anti-aging performance of CRMA60-22% was the least weakened, while that of CRMA60-22%-2.5% Sasobit was the most significantly weakened, and Sasobit had a negative impact on the long-term anti-aging performance of CRMA. CRMA60-22% increased significantly. The effect of Sasobit on weakening the aging resistance of asphalt increased with the increase of aging degree. Meanwhile, nano-TiO₂ had an improving effect on the anti-aging performance of CRMA60-22%-2.5% Sasobit. After PAV aging, the rubber powder reduced the complex modulus index (CMI) value of 70# asphalt by about five times, indicating that the rubber powder was more beneficial to control asphalt hardening and improve temperature sensitivity, while Sasobit, nano-TiO₂ increased the thermal sensitivity of CRMA60-22%.