Effect of chemically treated recycled tire aggregate on the resistance to chloride ion penetration of concrete

The utilization of recycled tires as a building construction material in concrete production could significantly contribute to sustainable development. The results of several studies have been reported by the research community dealing mainly with the strength (compressive and tensile) of concrete mixes with recycled tire aggregate (RTA). However, limited research has been focused on the durability of concrete made with RTA. Therefore, this research investigates the chloride penetration of fired clay brick aggregate (FCBA) concrete containing 0%, 10%, 20% and 50% (% vol.) RTA. The RTA was rinsed with tap water (i.e., untreated RTA named UTRTA) and treated with 20% sodium hydroxide (NaOH) (i.e., chemically treated RTA named CTRTA) for 2 h. The experimental results show that the concrete made with both UTRTA and CTRTA has higher chloride diffusion than FCBA, as the transmitted charge in Coulombs was higher with the increasing percentage of UTRTA and CTRTA. However, it was found that the concrete containing CTRTA provides better resistance to chloride penetration than UTRTA. This could be due to the enhanced bond between CTRTA and cement paste due to the improved surface roughness by NaOH. Furthermore, a good linear relationship of chloride penetration with compressive strength was observed. This study reveals that CTRTA can be used as a partial replacement for FCBA due to its enhanced durability. Also, it is shown that CTRTA could eliminate the dumping problem, resulting in lowering environmental impact as tires are not bio-degradable, reduce carbon footprint, decrease the need for new aggregate, more economy, and sustainability.