AN EXPERIMENTAL INVESTIGATION ON THE PERFORMANCE OF BACTERIAL CONCRETE

Abstract

Concrete is the most used building material composed of cement, sand, stone and aggregate. Tiny micro-crack is the main reason to cause failure in concrete structure. A noble technique has been developed in recent years to remediate these cracks by incorporating special species (bacillus) of bacteria in concrete. These types of bacteria have the capability to secret calcite precipitation and eventually repair the cracks. This paper investigates the performances of bacterial concrete exposed to plain water. Concrete specimens of 100 mm cubical size were cast and cured for 120 days with and without using bacteria. Using spectrophotometer to determine optical density has always been a central technique in micro-biology. Concrete specimens having OD600 0.107, 0.20, 0.637 and 1.221 have been studied in plain water. The specimens were taken out periodically and subjected to compressive & tensile strength tests. From the investigation, it has been revealed that microbial concrete having OD600 0.637 shows better resistance against strength deterioration under all curing conditions and curing ages. Later on the concrete specimens were subjected to Ultrasonic Pulse Velocity (UPV) tests. This study proposes the UPV and strength relationship curves for different microbial ratios used in concrete. From this test, it has been observed that specimens having OD600 0.637 shows better pulse velocity. The higher pulse velocity can therefore be used to assess the quality and uniformity of the concrete material.