Rusul Husham Abdulhussien, Hayder Abbas Obaid
Three kinds of asphalt were used in this study: conventional 40/50 asphalt, PG 76V-10, and PG 76E-10 modified asphalt to investigate the effect of modified asphalt on the performance of asphalt mixtures in binder and surface layers. The performance of the mixtures was assessed through tests measuring mixture stability, flow, moisture resistance, and crack resistance. The modified mixtures showed a decrease in optimal asphalt content (OAC), indicating improved aggregate coating and compaction. Mixtures containing polymer-modified asphalt—specifically PG 76E-10—achieved higher stability and density, lower flow and void ratio, and significantly improved resistance to moisture damage compared to conventional mixtures. Mixtures modified with PG 76E-10 also recorded the highest CT index (Crack Tolerance Index) values, indicating excellent resistance to cracking from repeated loading or thermal changes. The PG 76V-10 mixtures showed improved performance compared to conventional asphalt, but PG 76E-10 showed more pronounced improvements in most properties, especially in enhancing internal cohesion and reducing permeability. These results emphasize the importance of using polymer-modified asphalt in both layers to achieve better paving performance and emphasize the need for careful selection of the type of modified asphalt according to the function of the layer and the expected service conditions