EFFECT OF NAOH MOLARITY ON THE COMPRESSIVE STRENGTH OF CORN COB ASH-BASED GEOPOLYMERS WITH LIMESTONE POWDER ADDITIVES

Abstract

This study examines the effect of NaOH molarity and the addition of 20% limestone powder to 80% corn cob ash (CCA) on the compressive strength and durability of geopolymer materials. Specimens were prepared with NaOH molarities from 8 M to 16 M and tested at 7 days and 28 days. Results show that higher molarity increases compressive strength, with the hybrid mix (80% CCA + 20% limestone powder) outperforming 100% CCA. Specifically, the 7-day compressive strength for the hybrid mix ranged from 21 MPa to 38.59 MPa, and the 28-day compressive strength ranged from 28 MPa to 45 MPa, compared to 12.5 MPa to 20 MPa at 7 days and 17.5 MPa to 27.5 MPa at 28 days for the 100% CCA mix. However, efflorescence got worse as the molarity increased. For future work researchers should focus on different NaOH molarities, along with some additives to reduce efflorescence, and finding alternative materials for enhanced sustainability. This study pinpoints the potential use of corn cob ash-based geopolymers as strong and sustainable construction material.