Performance Evaluation of Asphalt Binder and Mixture Modified by Amorphous Poly Alpha Olefins (APAO)

In this paper, to prepare modified bitumen, bitumen was mixed with 0%, 4%, 6% and 8% amorphous poly alpha olefin (APAO). Based on the tests of penetration degree, flexibility, softening point and dynamic shear rheometer test (DSR), the amount of 6% APAO was determined as the optimal percentage in terms of bitumen performance. Continuously graded stone materials were mixed with APAO in order to prepare mixtures modified with APAO. The volumetric parameters of asphalt mixture with bitumen modified with APAO were tested. Standard Marshall Strength test, saturated Marshall Test, post-frost cracking test and Marshall Strength test of asphalt mixtures after aging were performed on asphalt mixtures with bitumen modified with APAO. Based on the Marshall Strength test, saturated Marshall Test and post-frost cracking test, the asphalt mixture with 6% APAO had better performance at high temperatures, more resistance to moisture damage and reduced minimum tensile strength after frost conditions. Tensile strength decreased after adding APAO. The difference in tensile strength between asphalt mixture with 4% APAO and 6% APAO was only negligible. Based on the Marshall Strength and Marshall Strength ratio (RMSR) 3 of the asphalt mixtures after aging, the optimal amount of APAO was 6%. Therefore, 6% APAO was determined as the optimum amount for both modified bitumen and asphalt mixture with APAO.