Laboratory investigation of waste tire rubber and amorphous poly alpha olefin modified asphalt

In recent years, waste tire rubber (WTR) has been widely used as an asphalt modifier, due to its good interaction with asphalt particles. Another modifier, amorphous poly alpha olefin (APAO) also gains popular interest from researchers because of its excellent miscibility with rubber, asphalt, and its remarkable aging resistance. This study aims at investigating the compound modification effect of WTR/APAO on the properties of asphalt binders. Their rheological features were measured through conventional and dynamic shear tests; low temperature performance was investigated by bending beam rheometer test; mixture stability was measured by storage stability test. The result of decreased penetration, increased softening point, elastic recovery, viscosity and complex modulus indicates that WTR/APAO compound modification improves the high temperature performance and rutting resistance of asphalt binders. Moreover the binders with additional incorporation of APAO obviously performed better than those modified with WTR alone, especially in storage stability. However, the modification effect of WTR and APAO on low temperature rheological properties of asphalt is unclear and controversial, as both creep stiffness and m-value decreased in the BBR test.