Asphalt modification and testing of the performance-related cracking failure properties

Asphalt, as a binder that glues the aggregates together, is an important part in the service life of asphalt pavement. However, its properties vary with time and temperature. Upon contact with oxygen, the compositions of an asphalt binder change causing the binder to harden and subsequently causing pavement failure. Additives, such as polymers and tire rubber, have been used to improve the performance of an asphalt binder. This work includes a study of how compositions of the base asphalt affect the performance of tire rubber-modified asphalt binders as well as a development of an aging procedure to assess the durability of an asphalt binder.; A number of base asphalt binders in various compositions were manufactured in the laboratory. Tire rubber was incorporated into the bases by high-cure process at high temperature. The blends were performance graded based on the procedures listed in the Superpave. The top performance grade was more influenced by the rubber content rather than the compositions as rubber addition increased the viscosity of the binder. On the bottom performance grade, the heavy aromatics reduced the resistance to cracking by several degrees.; Most pavement failures occur after several years of service. However, Superpave specification, G* sin δ, failed to screen for age hardening and fatigue cracking. DSR function, G′/(η ′/G′), which correlated well with ductility below 10 cm, offers an alternative approach to gauge fatigue failure on the road. To determine how an asphalt binder ages and when it cracks, an accelerated aging test had been developed based on the DSR function, using a failure limit of 0.003 MPa/s. As asphalt oxidation depends highly on pressure and temperature, an aging condition with the smallest relative deviation from the aging in the environmental room was considered as the best test to simulate the road aging.; From the kinetics standpoint, an asphalt with high initial jump tends to harden in a slower rate than asphalts with low initial jump. Also, the correlation between activation energy E and the reaction order α shows that they are inversely correlated; hence there is an offsetting effect between pressure and temperature.