Study on the stress-strain full curve of recycled coarse aggregate concrete under uniaxial compression

The study of stress-strain full curves of recycled coarse aggregate concrete (RCAC) with different substitution rates at C25 and C35 strength grades is lacking, which is the basic theory for design and simulation. Therefore, this ignored problem was studied through experiment, theoretical analysis and simulation. Firstly, the load -deformation full curve, failure process and failure mode of 48 RCAC prismatic specimens were studied by uni-axial compression test. Secondly, the peak compressive stress, elastic modulus, peak compressive strain, and ultimate compressive strain of RCAC with different substitution rates under different strengths were analyzed, and the formula was proposed. Then, it was found that the slope of the descending section of the stress-strain curve fluctuated after the addition of recycled coarse aggregate, which is different from the monotonic increase rule found by other scholars. The constitutive equation of natural concrete was used for RCAC, and the pa-rameters of the descending section for different substitution rates at C25 and C35 grades were obtained and verified. Subsequently, Software for Calculating RCAC Stress-Strain Curve was developed for the convenient application of the proposed constitutive equation. Finally, the tests were simulated by the concrete damage plastic (CDP) model, and the parametric study found that the expansion angle and mesh size had little effect on the results, but had a significant impact on the computational cost. The smaller the viscosity coefficient, the more accurate the calculation result and the longer the time-consuming. The conclusions are meaningful for the design and fine analysis of RCAC structure.