Improving the Low-Temperature Performance of RET Modified Asphalt Mixture with Different Modifiers

To improve the low-temperature performance of RET (Reactive Elastomeric Terpolymer) modified asphalt mixture (RETM), polyurethane prepolymer (PUP) was used by wet process, ground waste rubber (GWR) and fibers were used by dry process. Tests of force ductility, bending beam rheometer (BBR), differential scanning calorimeter (DSC), viscosity and multiple stress creep recovery (MSCR) were conducted to study the effects of PUP on the performance of RET modified asphalt (RETA), and beam bending test was conducted to study the effects of GWR and fibers on the performance of RETM. Then, tests of beam bending, wheel tracking, Marshall immersion, freeze-thaw splitting, and economic analysis were further conducted to compare the performance and economy of RETM modified with optimum modifiers suggested. All modifiers improve the low-temperature performance of RETM. PUP content, the content and size of GWR and the content and type of fibers significantly affect the performance of RETA or RETM respectively. After analysis, 10% PUP, 2.1% 80 mesh GWR and 0.2% polyester (PE) fiber are considered as the optimum modifiers, respectively. Comparison results show that optimum modifiers variously improve the low-temperature performance, rutting resistance and moisture susceptibility of RETM, but they slightly reduced the economy of RETM. Comprehensive evaluation shows that 2.1% 80 mesh GWR and 10% PUP are better than 0.2% PE fiber.