Equation for stress–strain relationship of recycled aggregate concrete in axial compression

The experimentally observed behaviour of normal-strength recycled aggregate concrete made with varying amounts of coarse recycled concrete aggregate (RCA) in uniaxial compression was modelled using a single polynomial-based equation valid for both the ascending as well as the descending branches of the stress–strain relationship. The measured stress–strain relationships of companion cylindrical specimens were averaged using a simple procedure that was found to be effective. The proposed constitutive model reflected the experimental trend that, although the strain at peak stress increased with an increase in the replacement level of coarse RCA, the ultimate strain was not affected significantly whereas the compressive strength and the static modulus decreased. The predictions of the proposed model were found to be in good agreement with experimental results reported in the literature.