PENGARUH SUBSTITUSI ABU SEKAM PADI PADA SEMEN DAN ABU BONGGOL JAGUNG PADA AGREGAT HALUS TERHADAP KUAT TEKAN DAN KUAT LENTUR BETON

Abstract

This study aims to investigate the effect of rice husk ash (RHA) as a partial replacement of cement and corn cob ash (CCA) as a partial replacement of fine aggregate on the compressive and flexural strength of concrete at 28 days. The concrete was designed with a target strength of 20 MPa. RHA was used at 6% by weight of cement, while CCA was varied at 4%, 5%, 6%, and 7% by weight of fine aggregate. Testing was performed using cylindrical specimens for compressive strength and beam specimens for flexural strength at 28 days. The control concrete (without additives) had a compressive strength of 10.191 MPa. The addition of 6% RHA and 4% CCA increased compressive strength to 13.135 MPa, rising to 13.531 MPa at 5% CCA, and reaching a peak of 13.701 MPa at 6% CCA, an increase of 34.4% compared to the control. However, at 7% CCA, compressive strength decreased to 12.059 MPa. For flexural strength, the control concrete reached 3.081 MPa, while the highest value of 3.595 MPa was obtained at 7% CCA, an increase of 16.7%. The results indicate that RHA and CCA can improve the mechanical properties of concrete, with different optimum percentages for compressive and flexural strength

Keyword: Concrete, Rice husk ash, Corn cob ash, Compressive strength, Flexural strength