Strength and electrical resistivity of recycled concrete made of aggregates from waste bricks

Abstract

This study aimed to investigate the mechanical and electrochemical properties of concrete that uses recycled brick aggregate (RBA) as a substitute for natural coarse aggregate (NCA). The study focusses on the workability, compressive strength and the electrical resistivity of concrete made with RBA. To test the effects of incorporating RBA on the properties of concrete, 6 different mixes were made with increasing incorporation percentages (0%, 20%, 40%, 60%, 80%, 100%). It was found that the negative effect of RBA on the workability of concrete can be negated using additives such as plasticizers. The study also showed that the compressive strength of concrete was reduced from 54 MPa for control specimens to 30 MPa at 100% replacement of RBA (44% reduction). No significant reduction in strength was observed in RBA replacement range between 60 to 100%. Additionally, the study showed that a harsh environment with high chlorideion concentration has no negative impact on the compressive strength of concrete. Finally, the results of the electrical resistivity (ER) test showed that higher RBA% tend to decrease the ER of concrete both immediately and over-time. Overall, the decrease in electrical resistivity resulting from the usage of RBA in the concrete puts the steel reinforcement at high risk of corrosion; therefore, protective measures must be employed when using RBA under severe exterior exposure.