Engineering properties of treated recycled concrete aggregate (RCA) for structural applications

• The use of low concentration acid has significant to remove the loose adhered mortar on RCA surface.
• The physical performance of RCA after acid treatment was improved and satisfied with specification requirement.
• The amount of mortar loss is greatly influence with the molarity of acid.
• The slump and density of concrete containing treated RCA is comparable with concrete containing with untreated RCA.
• The use of treated RCA produced concrete with higher compressive strength as compared to untreated RCA.

One method to promote and encourage maximum recycled concrete aggregate (RCA) utilisation for structural concrete applications is to minimise the adverse effects of RCA on concrete performance. The formulation of an appropriate recycling process in RCA production with improved properties is desirable. This study aims to develop a potential treatment of RCA by using low-concentration acid as an alternative method to produce high quality RCA for structural concrete applications. This work aims to study the effect of using different molarities of acid solvent and age of treatment (soaking) on properties of RCA, as well as the influence of using this treated aggregate on the properties of concrete. The results show that the use of different acid molarities to remove or minimise loose mortar particles attached on the surfaces of RCA can significantly improves its physical and mechanical properties. In addition, the reduction of loose mortar that covers RCA particles can significantly improves surface contact between the new cement paste and the aggregate which subsequently resulted in a significant improvement in the strength of concrete mechanical. However, the effectiveness of these treatment methods remains dependent on several factors that require further consideration.