Biocementation: A Green Technique in Civil Engineering

Abstract

Concrete and mortar are most used construction materials worldwide and their usage is rapidly increasing with growing need for urbanization. However, these construction materials are highly susceptible to deterioration. There is an intense need to develop the techniques to strengthen the construction materials without harming environment. Microbially induced calcium carbonate precipitation or biocementation is one of such green techniques which implicates the precipitation of calcium carbonate by microbial mass. Some of the soil bacteria have tendency to precipitate calcium carbonate with the help of urease enzyme, which they produce as a part of their metabolic activities. This process is known as urea hydrolysis which produces CaCO3 depositions. When incorporated in the matrix of construction materials, these depositions tend to pack up the micro voids in the matrix and thus ultimately leading to the strength enhancement of construction materials. Present study focuses on the enhancement of mechanical properties of biocemented cement mortar. Biocementation in cement mortar specimen caused approximately 20 % increase in compressive strength and 17% reduction in water absorption.

Keywords: biocementation, MICCP, ureolytic bacteria, calcium carbonate