Recycled Coarse Aggregate from Concrete Waste Using DMDA for Concrete

Abstract

This study investigates the effect of the replacement of recycled concrete as coarse aggregates using the Densified Mixture Design Algorithm Method (DMDA) in unconfined concrete behavior. DMDA was applied to produce concrete with the least void. Compressive strength, flexural strength and split tensile strength tests were conducted on 7-, 14-, 28- and 56-day old specimens. Compressive strength test results showed that specimens with 20, 30, and 40% RCA replacements at 56 days are relatively lower compared to the control and with 10% RCA replacement specimens. The compressive strengths of the specimens with RCA replacements decreased as the amount of RCA increased. However, the 10% replacement specimens showed promising performance with an average strength of 3275 psi at 56 days with an 11.2% difference in compressive strength with the control with 0% replacement. A significant increase in compressive strengths between the 28- and 56-day specimens for all specimens was observed and accounted due to the pozzolanic activity of the type C fly ash used as filler. For flexural and splitting tensile strength, results showed that specimens with 40% replacement showed best performance with a 9.87% difference and roughly 1% greater with the control in terms of its flexural and splitting tensile strength, respectively.