Performance evaluation of cement modified asphalt rubber binder through optimizing aging indexes

With increasing heavy traffic loads and expanding transportation networks, the engineering quality of asphalt pavements must be continuously improved. Previous research has shown that waste tire rubber and cement can enhance the overall properties of asphalt binders and mixtures. However, the performance evaluation of cement and rubber-modified asphalt binders, especially in terms of aging characteristics, remains unclear. This study investigates the appropriate aging index to evaluate the modification effects of combining cement and rubber in asphalt binders using thermal oxygen aging tests. A series of chemical and rheological tests, including Fourier Transform Infrared (FTIR) Spectroscopy, Dynamic Shear Rheology (DSR), softening point, and penetration, were conducted. Various aging indexes were compared through orthogonal optimization analysis. Results indicated that cement content up to 2.5 % enhances the high-temperature stability and hardness of CRMA binders, with a 6.7 % increase in softening point and a 4.7 % decrease in penetration. However, excessive cement content (above 2.5 %) leads to particle agglomeration, reducing penetration by 21 % and accelerating aging degradation. Rheological analysis showed that thermal oxidative aging and moderate cement content improve high-temperature deformation resistance. Among the developed aging indexes, the rutting factor index (RFI) exhibited the lowest variance, confirming its reliability for evaluating modification effects. This study provides crucial insights for optimizing aging indicators and improving the durability of asphalt binders.