Fresh and hardened properties of concrete made with recycled brick aggregate

To understand the prospect of recycling recycled brick aggregate (RBA), concrete samples were collected from 50 demolished building sites over a period of 20 years. After investigation of the properties of RBA, concrete specimens (RBAC) were fabricated using recycled brick aggregate (RBA). The variables were W/C (0.55, 0.45, 0.40 and 0.35) and cement content (340, 400, 450 and 500 kg/m³). As control case, virgin brick aggregate (BA) and concrete made with brick aggregate (BAC) were also investigated. For fresh concrete, slump was measured. For hardened concrete, compressive strength, stress–strain curves, Young’s modulus, tensile strength, ultrasonic pulse velocity (UPV)) were evaluated. Moreover, by using a scanning electron microscope (SEM), interfacial transition zones (ITZs) in and around RBA were evaluated. RBA shows lower water absorption and lower abrasion compared to the virgin BA. Based on the abrasion value of RBA; the RBA was classified as excellent, good, and poor. RBA can be used to produce concrete of different grades from 21 to 34 MPa. A statistical regression model was developed considering compressive strength as dependent variable and W/C, cement content, age, and abrasion of RBA as independent variables.