Dynamic compressive-tensile moduli of asphalt mixture and its applications to pavement response prediction
Cheng Huailei1 Sun Lijun1 Zheng Jianlong2 Qian Guoping2 Liu Liping1 Yang Ruikang1
1. Key Laboratory of Road and Traffic Engineering of the Ministry of Education, Tongji University, Shanghai 201804, China;
2. National Engineering Laboratory of Highway Maintenance Technology, Changsha University of Science & Technology, Changsha 410114, China
Abstract：The modulus of the asphalt layer is one of the essential parameters used for pavement response prediction. The determination of asphalt layer modulus directly affects pavement design results. Due to the effect of aggregate interlock, asphalt mixture subjected to compressive and tensile stresses exhibits bi-modulus properties. This research aimed at investigating the dynamic compressive-tensile moduli of asphalt mixture and applying the asphalt mixture’s compressive-tensile moduli to analyzing the pavement response. Firstly, a calculation method based on the FE model with bi-modulus theory was established to calculate the compressive-tensile moduli of the asphalt mixture in indirect tensile test. Secondly, one dense graded asphalt mixture named AC-13 was used to demonstrate the differences of compressive-tensile bi-modulus and single moduli and the differences of compressive-tensile Poisson’s ratio and single Poisson’s ratio. Finally, the compressive-tensile moduli and Poisson’s ratios were applied for the pavement response prediction, and the corresponding prediction results were compared to those from the current single-modulus method so that the pavement response characteristics from the two types of modulus methods and their relationships can be analyzed. The research results disclose that in the whole frequency domain, the master curve of compressive modulus of mixture is evidently greaterthan that of tensile one; the modulus calculated from the single-modulus model is close to the compressive modulus compared to the tensile one, and the single-modulus model failed to predict the Poisson’s ratio of the mixture at intermediate and high temperatures; the compressive-to-tensile modulus ratio for asphalt mixture ranges from 1.6 to 4.0, and the ratio may increase with the temperature. Compared to the bi-modulus system, the single modulus system may underestimate the strain response of flexible pavement and the maximum shear stress response of flexible/semi-rigid pavement, but the deflection responses predicted from the two systems are generally consistent. This research may provide references for improving the pavement design in which the difference of compressive modulus and tensile modulus of asphalt mixture shall be taken into account.
