Investigation of Compressive and Flexural Strength Behavior of Recycled Aggregate Concrete for Structural Applications

Abstract

The construction sector produces large amounts of construction and demolition (C&D) waste annually, and at the same time consumes natural aggregate resources required to make new concrete. Recycled Aggregate Concrete (RAC) is a concrete type that is currently being discussed as a way to achieve sustainable construction by replacing natural coarse aggregate with processed C&D waste. This work examines the compressive and flexural strength behavior of concrete that is manufactured using recycled coarse aggregate (RCA) at 0, 25, 50, 75 and 100 weight percentages of natural coarse aggregate. Concrete specimens were cast and allowed to dry as per the ASTM standards and were tested at 7 days and 28 days of compressive strength, flexural strength, and water absorption at 28 days. Findings show that the mechanical strength steadily decreases with the concentration of RCA as a result of the residual mortar attached to the recycled particles and as a consequence of the weaker interfacial transition zone (ITZ). Compressive strength declined by about 30 percent compared to the control mix at 100 percent replacement and flexural strength declined by about 33 percent. But, at a maximum replacement of 2530 percent, the strength deterioration was still within a reasonable structural tolerance of 58 percent, indicating that RAC can be utilized in structural applications with reasonable design compromises at moderate replacement proportions. The results justify the wider use of RAC as an ecologically sound and structurally viable substitute to traditional concrete.