The effect of super performance grade (SPG) polymer on properties of bitumen and hot mix asphalt (HMA)

Moisture damage and rutting are the most prevalent defects of hot mix asphalts (HMA). Adhesion between materials and bitumen is an important factor that affects the failure of the asphalt mixtures. Various methods, such as using additives in the form of bitumen extender, have strengthened the asphalt mixture's resistance to moisture and rutting. In this study, super performance grade (SPG) polymer was used as a bitumen extender to improve bonding between asphalt binder and aggregates. Four types of HMA containing PG 58–22 bitumen with a replacement percentage of 20, 30, 40, and 50 SPG were prepared for this goal. Conventional properties of bitumen such as specific weight and viscosity (at 120, 135, and 160 °C), compaction temperature, and bitumen mixing as well as mechanical properties of the HMA such as moisture susceptibility with tensile strength ratio and Marshall stability ratio tests, and rutting (Marshall ratio) were evaluated. The results showed the improvement of conventional bitumen properties due to the addition of SPG. According to the results, SPG polymer as an extender bitumen increased the specific weight and viscosity of the bitumen as well as the density temperature and mixing of the mixture. The mechanical properties results also showed that adding SPG polymer as a bitumen extender improved the adhesion between bitumen and aggregates, leading to increased moisture and rutting resistance.