The Biaxial Compressive Mechanical Properties and Strength Criterion of Recycled Aggregate Concrete Under Different Dynamic Strain Rates

Abstract

In this paper, the tests under biaxial compression were conducted on five kinds of recycled aggregate concrete (RAC) by stress ratios (0:−1, −0.1:−1, −0.25:−1, −0.5:−1, −0.75:−1, and −1:−1) at the strain rates of 10–5/s, 10–4/s, 10–3/s, and 10–2/s. This study was accomplished in the servo-hydraulic multi-axial testing system, which was carried at Dalian University of Technology. The experimental phenomena of RAC under biaxial compression are described, and the experimental results of biaxial compressive strength of RAC are analyzed. The effects of strain rate, stress ratio, and substitution percentages of recycled coarse aggregate (RCA) on the biaxial compressive strength of RAC were studied. During the experiments, the failure modes of concrete have not been changed because of the increased impact of the RCA on RAC. The strength of RAC is improved with the increase in strain rates. With the increase in stress ratios, the biaxial compressive strength increases at first. However, the strength then decreases. Based on the strength theory of common concrete and analysis of experimental data, this paper built a new dynamic strength criterion. The biaxial compressive strength criterion describes the characteristics of structural RAC at different stress ratios and strain rates. This strength criterion can provide theoretical foundation for future concrete multi-axis dynamic tests and the design specification with the considerations of multi-axis dynamic strength and nonlinear analysis. The feature of the model is that it can take into account the influence of strain rates.