Micromechanical Model for Temperature Effects of Hot-Mix Asphalt Concrete

The stress-strain behavior and internal structure of hot-mix asphalt (HMA) concrete due to the change in temperature was investigated. A micromechanical model, ASBAL, was used to simulate the stress-stain behavior and variation of the internal structure of HMA. The ASBAL program is a modification of a computer program based on the discrete element method. The Burgers’ element was added to ASBAL to describe the viscoelastic behavior of asphalt cement. The master curves of asphalt binder, which describe the stress-strain behavior of asphalt cement, from Strategic Highway Research Program research at different temperatures, were used. The Burgers’ element parameters of springs and dashpots were backcalculated at different temperatures from master curves. The resulting Burgers’ parameters and other properties of asphalt and aggregate were used to simulate the mechanical behavior of HMA. Behavior of HMA at four different temperatures subjected to constant-P (average stress) compression and triaxial compression tests were simulated. Both simulations showed effects of temperature on the stress-strain behavior, with higher strength and stiffness at low temperatures. Beyond 25°C, the specimen temperature did not seem to be a major contributor to the shear strength. At higher temperature during shear, there was a smaller number of dry and asphalt contacts.