Comparative Study of Compressive Strength between Natural Concrete and Recycled Concrete

https://doi.org/10.46610/JOCCE.2026.v012i02.003

Abstract

This study discusses the use of recycled coarse aggregate (RCA) as a partial replacement for natural coarse aggregate (NCA) in concrete construction. Three replacement proportions (15%, 30%, 45%) were used to compare compressive strength and material cost with 0% replacement concrete. The mix design of 1:1.36:2.67 was used with a water-cement ratio (w/c) of 0.45. Compressive strength was determined at 14 days and 28 days by testing 6 cubes for each proportion. Among all proportions, including 0% replacement, the average compressive strength for 14-day and 28-day concrete at 30% replacement was 36.66 MPa and 37.83 MPa, respectively—the highest overall. Non-destructive test (rebound hammer) numbers ranged from 26 to 29, indicating fair concrete. Impact values (19–25%) and Los Angeles Abrasion values (18–29%) suggest suitability for wearing courses. Cost analysis showed up to 13.22% reduction in material cost with 45% RCA replacement. It is concluded that NCA can be replaced by RCA up to 45% when the RCA age is approximately 2 years.