Treated Recycled Concrete Aggregate for Concrete Structural Members

Abstract

This study explored the innovative use of Recycled Concrete Aggregate (RCA) combined with Super Absorbent Polymers (SAP) as a sustainable alternative to Natural Aggregate (NA) in concrete production. Addressing the traditional limitation of RCA usage to 30% due to water absorption and reduced strength, this research successfully increased the RCA content to 50% using a Two-Stage Mixing Approach (TSMA). Three concrete mixtures were tested: conventional concrete and two mixtures containing 50% RCA and 50% NA, incorporating 0.11% and 0.3% SAP by cement weight. Compressive and flexural strength tests conducted on cylindrical and beam samples after 28 days revealed that the flexural strength of the recycled concrete mixtures was comparable to that of traditional concrete, meeting the standards set by the Department of Public Works and Highways (DPWH). Notably, the mixture with 50% RCA, 50% NA, and 0.3% SAP achieved the highest compressive strength, surpassing the American Concrete Institute (ACI) standard of 17 MPa (2500 PSI). These findings highlighted the potential of TSMA and SAP to enhance the structural performance of RCA-based concrete, making it a viable and sustainable alternative to conventional concrete. This study introduced a novel method for increasing RCA utilization in structural applications, significantly reducing construction waste and promoting environmentally sustainable practices in the construction industry.