Evaluation of Concrete Strength Made with Recycled Aggregate

The construction industry consumes enormous quantities of concrete, which subsequently produces large amount of material waste during production and demolishing. As a result, the colossal quantity of concrete rubble is disposed in landfills. This paper, therefore, evaluated the feasibility of reusing waste concrete as recycled aggregate (RA) to produce concrete. The replacement levels were 20, 50, and 80% RA of normal coarse aggregate. Micro silica (MS) and fly ash (FA) were used as cementitious replacement material, however, the water-to-binder ratio (w/b) was kept constant at 0.31. A total of 44 specimens were used to evaluate the fresh and hardened properties. Concrete with 80% RA showed good workability and mechanical properties. The compressive strength of the concrete with 80% RA was 60 MPa at 28 days and 77 MPa at 56 days. Rapid chloride penetration test (RCPT) was also conducted, where the concrete with 80% RA had the lowest permeability.