An Experimental Investigation on the Strength and Durability Aspects of Bacterial Concrete with Fly Ash

Abstract

This paper presents the results of an experimental investigation carried out to evaluate the influence of Bacillus sphaericus bacteria on the compressive strength, split tensile strength, flexural strength, shear strength, water absorption and chloride permeability of concrete made without and with fly ash. Cement was replaced with two percentages (10 and 20) with fly ash by weight. Three different cell concentration (0, 10³,10⁵,10⁷ cells/ml) of bacteria were used in making the concrete mixes. Tests were performed at the age of 28 days. Test results indicated that inclusion of B. sphaericus in fly ash concrete enhanced the compressive strength reduced the water absorption and chloride permeability of fly ash concrete. Maximum increase in compressive strength 15.47% was observed with 10⁵cells/ml of bacteria. This improvement in strength was due to deposition on the bacteria cell surfaces within the pores.

The present work highlights the influence of bacteria on the properties of concrete made with supplementing cementing material such as like fly ash. Usage of bacteria like B. sphaericus improves strength and durability and strength of fly ash concrete through self-healing effect.

Keywords: Bacterial concrete, Bacillus sphaericus, compressive strength, water absorption, chloride penetration