Relating Field Moduli of Asphalt Mixture Layer Under Vehicular Loading and its Dynamic Moduli Under Laboratory Loading

The modulus of the asphalt layer is an essential input parameter in asphalt pavement design. For design purposes, the relationship between field and laboratory moduli of the asphalt mixture layer needs to be identified. In this research, the field modulus of the asphalt layer is predicted via a developed field modulus master curve. The laboratory modulus of asphalt mixture is measured using three different loading modes, namely uniaxial compressive (UC), indirect tensile (IDT), and four-point bending (4PB) modes. The loading mode is observed to affect the mixture's laboratory modulus. The asphalt mixture moduli measured from UC mode are generally the highest, following by those from IDT mode, whereas the 4PB mode generates the lowest asphalt mixture moduli. By comparing field and laboratory moduli of asphalt mixture, it is found that the laboratory modulus from 4PB mode yields satisfactory predictions for the mixture's field modulus in a wide range of loading frequencies. The UC and IDT modes, which tend to overpredict the field modulus of the asphalt layer, need to be modified. The modification factor ranges between 0.3 and 0.7 for UC mode, and varies from 0.2 to 1.0 for IDT mode. For both modes, the modification factors grow closer to 1.0 with increasing frequencies and decreasing temperatures, implying that UC and IDT modes become increasingly suitable for simulating field conditions at high frequencies and low temperatures.