Mechanical properties and strength index conversion of recycled aggregate concrete under direct shear

In order to study the effect of replacement rate of recycled aggregate concrete (RAC) on the direct shear performance of concrete, 75cubic specimens incorporating different replacement rates of RCA were fabricated. The direct shear test, compressive strength test and splitting tensile strength test were carried out. The failure mechanism of direct shear and the conversion rule between different strength indexes of RAC were revealed. The results show that RAC is obviously brittle failure under direct shear and both the coarse aggregate and cement matrix are sheared. With the increase of the replacement rate, the direct shear strength of RAC has little change compared with the ordinary concrete, and shows a decreasing trend in general. However, the direct shear strength of RAC increases when the replacement rate is 50% (by mass). The peak shear deformation generally increases by 18.85% and the initial shear deformation modulus decreases by 8.97% on average. Finally, based on experimental data, the conversion relationship of RAC between the shear and the compressive and split tensile strength was proposed. The calculated results are in good agreement with the experimental values. © 2021, Editorial Office of Acta Materiae Compositae Sinica. All right reserved.