Impact of Incorporating Rice Husk Ash (RHA) into Recycled Concrete Aggregates (RCA) on the Compressive and Flexural Strength of Concrete

Abstract

This study aimed to assess the strength characteristics of concrete using Recycled Concrete Aggregates (RCA) as full replacement to coarse aggregates and Rice Husk Ash (RHA) as an admixture. The concrete samples were subjected to curing for 7, 14, and 28 days. Specifically, the study evaluated the workability of freshly mixed concrete and compared the compressive and flexural strength with RCA and RHA to normal concrete. Four different treatment mixtures were used with three replicates with varying ratio of RHA to cement: Treatment 1 (1 cement: ¾ RHA), Treatment 2 (1 cement: ½ RHA), Treatment 3 (1 cement: ¼ RHA). In all cases, RCA completely replaced natural coarse aggregates. The results indicated that the slump which measures the workability of the RCA concrete met the desired standard specifications. Additionally, the RCA concrete with the highest RHA content obtained the highest compressive and flexural strength on the 28th day test but did not exceed the control. Furthermore, the study revealed that the concrete specimens could handle maximum loads for flexure rather than compression load.