Improving the prediction of the dynamic modulus of fine-graded asphalt concrete mixtures at high temperatures

Predictive techniques for estimating the asphalt concrete dynamic modulus, |E*|, from mixture volumetric properties are widely used in pavement design and evaluation. The reliability of these techniques is lowest at high service temperatures above 35 °C. Rutting is one of the major distresses in asphalt pavements and is considered highly sensitive to |E*| at high temperatures. The objective of this paper is to improve the reliability in the prediction of |E*| at high temperatures using parameters that reflect the gradation of aggregates. A linear model is proposed to adjust the predicted |E*| for fine-graded mixtures using a new gradation parameter. The analysis was performed on 24 mixtures prepared from various aggregate gradations and types, and several binder grades. Reasonable results were predicted for the calibration data and a validation dataset from the literature. The correlation between |E*| at high temperatures and the gradation parameter improved when it was carried out independently on fine- and coarse-graded mixtures.