Influence of temperature on J_nr values of polymer modified asphalt binders

At desert environment, asphalt binders that have performance grades of PG 70-16 or PG 76-16 may show early signs of rutting under heavy loads due to lack of strain recovery when used in the design of asphalt mixes and structures. Type and amount of polymer in addition to testing temperature are the major factors that affect the recovery properties of asphalt binders. This study was conducted to evaluate J_nr parameters of four different polymers (Styrene–Butadiene–Styrene “SBS” Crumb Rubber “CR” light density Polyethylene “PE” and modified Olefin “OF”) used to modify asphalt binders. Asphalt samples were tested at various temperatures and regression models were created. These models are useful to properly select the polymer type and amount suitable to the area of concern and to be used in the design of pavement structures especially in Mechanical–Empirical Design Guide. It is found from this study that power-law models best described the relationship between J_nr and temperature with signs of shear thickening. The results of Styrene–Butadiene–Styrene Modified asphalt binders have shown best behavior of recovering the strain at high temperatures with Non-recoverable creep compliance (J_nr) values less than 0.5 obtained at 76 °C. Polyethylene and Olefin polymers could improve local asphalt binders at areas where PG 58 and PG 64 are required. The J_nr-temp curves can be considered as master curves for local conditions and material.