Different influence of replacement ratio of recycled aggregate on uniaxial stress-strain relationship for recycled concrete with different concrete strengths

This paper experimentally investigated whether the replacement ratio of recycled coarse aggregate (r) has different influence on stress–strain relation of concrete with different strength grades. The studied concrete specimens had two strength grades of C30 and C50, each with r ratios of 0, 25%, 50%, 75% and 100%. Test results showed that r ratio had significantly different influence on compressive strength, peak strain (the strain at peak stress, ε₀) and deformability (the ratio between ultimate strain and peak strain) of concrete with different concrete strengths. To account for such different influences, a stress–strain model of recycled aggregate concrete (RAC) was proposed by modifying key parameters in existing model of natural aggregate concrete (NAC), where r ratio and concrete strength were the main parameters. The proposed model was benchmarked against available test results of 58 RAC specimens.