Laboratory investigations on influence of thermoplastic polyurethane and its hard segment content on pavement performance of asphalt mixture

Thermoplastic polyurethane (TPU) is an excellent asphalt modifier, which is consisted of hard and soft segments in the TPU molecular chain. In this paper, The conventional road performances (high and low temperature performance, water stability, fatigue performance and aging resistance) of TPU modified asphalt mixture (TPU-AM) with different hard segment content were evaluated. The results proved that the hard segment of TPU can effectively improve the high temperature performance of asphalt. Compared with TPU-AM with high hard segment content, using TPU with low hard segment content as modifier, the low temperature flexibility and fatigue resistance of TPU-AM are significantly improved. TPU-AM with hard segment content of 40% has excellent high temperature performance, while the TPU-AM with hard segment content of 10% has the best fatigue ability and low temperature performance. The water stability of TPU-AM is obviously stronger than that of base asphalt mixture, although the content of TPU hard segment has little influence on the water stability of TPU-AM. The aging results show that TPU-AM has the best aging resistance when the hard segment content is 30%. Based on the above analysis, the high performance of TPU-AM can be designed by changing the hard segment content.