Acid Attack Resistance of Concrete Produced by Partial Replacement of Cement with Limestone Dust and Locust Bean Pod Ash

Abstract

Concrete, a widely used construction material, has an alkaline pH value of 12 – 13.5, which makes it susceptible to acid attacks. In this study, effect of acid (H2SO4) attack on concrete produced by partially replacing cement with limestone dust (LSD) and locust bean pod ash (LBPA) was investigated. LBPA was constant at 5% while LSD was varied at 5% intervals from 0 to 25% by weight of cement. Sulphuric acid solution of 5% concentration was used to examine the resistance of concrete specimens for a total exposure period of 28 days. The performance of the degraded specimens was evaluated by measuring the strength loss. The results show that the control mix’s compressive strength dropped from 31 N/mm2 before immersion to 23.15 N/mm2 after 28 days of immersion in a 5% H2SO4 solution. At 10% LSD-LBPA mix, the compressive strength before immersion dropped from 24.33 N/mm2 to 23.81 N/mm2 after immersion in a 5% H2SO4 solution. The least amount of strength loss of 2.14 percent was obtained at 10% mix. The control mix suffered the greatest loss of strength of 25.32 percent. Water absorption in the mixes decreased up to 10% mix, and then increased when LSD and LBPA were further added. At a 10% mix, the lowest rate of water absorption of 16.28 percent was obtained. Based on the findings, a 10% LSD-LBPA (5% LSD + 5% LBPA) mix produces concrete with better H2SO4 acid resistance than the control mix and is hereby recommended for concrete production in acidic environments.