Compressive performance and stress-strain relationship of geopolymer recycled brick aggregate concrete

Geopolymer recycled brick aggregate concrete (GRC), a new type of environmentally friendly material, can reduce carbon dioxide emissions and effectively utilise construction waste. To study its basic compressive performance and stress-strain relationship, cubes and prisms of GRC and ordinary recycled brick aggregate concrete (ORC) under five recycled brick aggregate (RBA) replacement ratios (0, 25, 50, 75 and 100%) were tested compressively. The failure mode, working performance, compressive strength, elastic modulus, Poisson's ratio and other indexes as well as the full stress-strain curves were obtained. The test results show that with the increase of RBA replacement ratio, the compressive strength and modulus of elasticity of GRC and ORC decrease, and the slump, strain corresponding to peak stress, transverse deformation coefficient and Poisson's ratio increase. Compared with ORC, under the same water-to-binder ratio, GRC exhibits 29% to 52% smaller elastic modulus, more than 30% reduction in slump, close Poisson's ratio and steeper decline branch of compressive stress-strain curve. Moreover, the RBA replacement ratio has a greater effect on GRC. Based on the uniaxial compressive model of ordinary concrete, the compressive constitutive models suitable for GRC and ORC are proposed.