A new simplified micromechanical model for asphalt mastic behavior

This study presented a new simplified micromechanical model that describes the asphalt mastic behavior at intermediate and high temperatures. Asphalt mastics were prepared using four fillers: glass, limestone, stone sawdust, and medical ash and one asphalt binder with a penetration grade of 60/70 (PG64-10). The mastics were prepared at four volume concentrations: 0.05, 0.10, 0.20, and 0.30. The Dynamic Shear Rheometer (DSR) frequency sweep tests were conducted at a wide range of temperatures and loading frequencies. A new model was developed for the mastic complex shear modulus value with a simplified form Gm=AGbB, such that A is a quadratic polynomial function of the volume concentration. The model had a high adjusted coefficient of determination (R2). It was validated using external measured data, and showed improved predictions of the mastic behavior. Findings also showed that the stone sawdust asphalt mastic had the highest complex shear modulus value at volume concentrations 0.05 and 0.10; whereas, at higher volume concentrations (0.20 and 0.30), the medical ash asphalt mastic and the glass asphalt mastic had the highest values, respectively. The stiffening effect of the asphalt mastics increased with the increase in temperature and the decrease in loading frequency.