The laboratory performance of asphalt mixture with thermoplastic polyurethane (TPU) and amorphous poly alpha olefin (APAO) compound modified asphalt binder

The using of waste polymer modified asphalt binder in pavement construction is cost effective and beneficial to the environment. In this paper, the modified asphalt binders are prepared by adding thermoplastic polyurethane (TPU, 0 %, 2 %, 4 %, 6 %, by weight of asphalt binder) and amorphous poly alpha olefins (APAO, 0 %, 2 %, 4 %, 6 %). The conventional physical, rotational viscosity and dynamic shear rheometer (DSR) tests were conducted on the modified binders and the results indicated that the addition of APAO could improve the rutting resistance the TPU modified asphalt binder, and the modified asphalt binder with 2 % TPU and 6 % APAO showed the best rutting resistance among the studied binders. To assess the effect of APAO dosage on the performance of TPU modified asphalt mixture, mechanical performance tests including Marshall stability, dynamic stability, indirect tensile, immersion Marshall, freeze-thaw splitting and long-term aging tests were carried out on asphalt mixtures with various TPU/APAO content combinations. The test results proved that 2 % TPU + 6 % APAO modified asphalt mixture showed better resistance to rutting and moisture damage, the superior long-term aging damage resistance, and the excellent anti-freeze-thaw damage ability, when compared to the unmodified asphalt mixture. According to the indirect tensile test results at-10 C, despite the indirect tensile strength (ITS) value of 2 % TPU modified asphalt mixture decreased after APAO added, the ITS value of asphalt mixture modified with 2 % TPU and 6 % APAO was still improved 5.8 % than base asphalt mixture. Based on the comprehensive analysis of the data, 2 % TPU + 6 % APAO modified asphalt mixture has superior road performance, and the performance characteristic of TPU/APAO compound modified asphalt mixture indicated that it could be applied for warmer regions.