Effects of the tensile strength and elastic modulus of low-strength brick aggregate concrete on the ultimate shear strength of short reinforced concrete columns

Ultimate shear strength of reinforced concrete columns made with low-strength brick aggregate concrete (BAC) is estimated using Mohr's circle and relevant failure criterion. Compressive tests and splitting tensile tests on concrete cylinders show that the material properties of BAC are distinctly different from those of stone aggregate concrete (SAC). In contrast to the well-known dependence between the splitting tensile strength and the square root of the compressive strength of concrete, a linear relationship between the splitting tensile strength and the compressive strength is proposed for BAC. The splitting tensile strength of BAC was lower than that of SAC of the same grade when the concrete compressive strength was below 25 MPa. Independent of the concrete strength, the elastic modulus of BAC was 70% of that calculated with the ACI code equation and 50% of that of SAC of the same grade. Twenty-six column specimens under constant vertical and cyclic horizontal loads are cited from a preliminary report of this research group (see Kabir et al. (2020)) for comparison with the estimated shear strength. A column specimen made with 13.0 MPa BAC exhibited a lower shear strength than that made with a similar grade of SAC. In the 22-23 MPa compressive strength range no distinct difference was observed. The difference in the tested shear strength originates from the distinct differences in the elastic modulus and splitting tensile strength.