Evaluation and Analysis of Asphalt Concrete Density Based on Core Samples

Abstract

Based on the general Marshall design method for asphalt mixtures, the difference of asphalt mixture density was determined according to the mechanical design method and volume design method. To improve the control accuracy of asphalt concrete pavement density, two design methods were established to determine the correlation of asphalt mixture density. In this study, samples were divided into original, core, and road core samples and selected as the research objects. First, the core samples of original asphalt concrete were formed and drilled by gyratory shear compacting press (PCG) compaction and core-drilling equipment in laboratory tests. Second, the density and volume indicators calculated by the quality of the original and core samples were measured according to the water gravimetric method. A correlation between the testing and the core samples could be established for the original samples. Finally, the corresponding data of the core samples obtained by Marshall test were compared with the data of mechanical design method. Test results show that the density and saturation of original samples increased by 1.4% and 9.8% compared with core samples, and inversely, the porosity and mineral gap ratio reduced by 24.8% and 7.6%. Data of the original and the core samples have a linear relationship and the correlation coefficients of density, porosity, saturation, and mineral gap ratio are 0.979, 0.975, 0.968, and 0.982, respectively. The optimum asphalt content of the Marshall test core samples is consistent with that of the gyratory testing machine (GTM) test; the density and volume index of the core samples are between the GTM and the Superpave test data. In conclusion, the degree of road compaction could be evaluated by the Marshall core samples more accurately than that of the original samples. For the units or areas without sufficient equipment for mechanical design of asphalt mixture, the density of Marshall core sample could be suggested to use for the detection and evaluation of asphalt pavement.