Establishment and application of theoretical-empirical prediction model of VMA in hot mix asphalt mixture

Voids in mineral aggregate (VMA) is a basic gradation design index of mineral aggregate in hot mix asphalt (HMA). In order to avoid the tedious process of selecting qualified gradation by obtaining measured VMA values from a large number of experiments, a prediction method of VMA value ranking without testing is established in this paper. Several theoretical-empirical models about VMA corresponding to skeleton porosity, skeleton dense and suspension dense gradations are set up, respectively. According to VMA standard value, measured VCA and the established equation for calculating the passing rate of 2.36 mm or 4.75 mm sieve of skeleton dense gradation, the gradation types of several gradations to be analyzed can be determined, and then the corresponding prediction model maybe selected to predict the VMA value of each gradation. The experimental results based on AC13 (Asphalt concrete with nominal maximum particle size of 13.2 mm) show that the estimated VMA size order is exactly consistent with the measured values, which demonstrates the effectiveness of the prediction method.