Recycled concrete aggregates of variable strengths used as subtitute to gravel in concrete.

In the call for alternatives to the use of concrete wastes, recycled concrete is used as a substitute to gravel in mixing concrete. This study involved comparing virgin concrete with recycled concrete in terms of their compressive strengths, specifically when the strengths of the virgin concrete from which the recycled aggregates or RCA was taken are varied. The experiments conducted in this study was divided onto three phases: (1) Making of Virgin Concrete Using Natural Aggregates, (2) Crushing of Virgin Concrete to Form Recycled Aggregates and (3) Making of Recycled Concrete Using Recycled Aggregates. The behavior of the recycled concrete in response to the varying strength of the recycled concrete aggregates was observed. From this, the factors that contributed to the loss or gain of the varying strength of recycled concrete when compared to their respective virgin concrete counterparts were determined and analyzed. From all the data gathered, observed, and analyzed, the researchers have led to the conclusion that the RCAs dictate the strength of the recycled concrete. Concrete using RCA was found to have higher compressive strength than the virgin concrete from which the RCA was obtained. Among the factors that contribute to the strength of the RCA is more angularity and rougher surface area. It was also observed as the strength requirements increased, the increase in strength of the RC decreased. This could be attributed to the weakening in compressive strength of the adhered mortar, bonds, and new mortar as design strength increases