Water Stability and Low-Temperature Performance of Polyolefin-Modified Recycled Asphalt Mixtures

The performance of asphalt mixtures containing high dosages of recycled asphalt pavement (RAP) still presents challenges under wet and low-temperature conditions, particularly in terms of water stability and low-temperature performance. In this research, the rutting resistance of polyolefin-modified recycled asphalt mixtures (P-RAMs) was first evaluated through rutting experiments. Subsequently, the water stability of P-RAM with different dosages of polyolefin was compared using immersion Marshall tests and freeze–thaw splitting tests. In addition, the low-temperature performance of P-RAM and functional groups of polyolefin-modified asphalt were analyzed. The experimental results show that, compared to recycled asphalt mixtures (RAMs), polyolefin increases the dynamic stability by approximately two times. Furthermore, when the polyolefin dosage exceeds 0.3%, the tensile strength ratio (TSR) value of P-RAM is greater than 90%, indicating an improvement in water stability. Similarly, polyolefin also enhances the low-temperature cracking resistance, although the improvement is less significant compared to water stability. Overall, polyolefin modification is promising for optimizing the performance of asphalt mixtures with high dosages of RAP.