INFLUENCE OF BACTERIA ON STRENGTH CHARACTERISTICS OF A SWELLING SOIL WITH CALCITE

Studies on microorganisms in soils is necessary for understanding the behaviour of soils and mechanism developing for deciding the nature of the soil. The microorganisms may exist in soil or induced into the soil. These studies are referred to with different names based on the intended purpose. Soil Microbiology encompasses the study of microorganisms and their processes in soil The interaction of organisms with each other and their environments involve Soil Ecology. Soil Biochemistry includes microbial processes, soil enzymes, and the formation and turnover of soil organic matter. Microorganisms/ Microbes are classified as Bacteria and Virus. Most of the Bacteria are useful to humankind and virus have provoking effects on the environment as well as on human beings. At present bacteria is used in several civil engineering applications as listed in recent research work in literature. From the Civil Engineering perspective, When the water content of some soils changes, problems arise in structures resting on swelling soils, mainly the strength of swelling soils decrease drastically. In the present paper chemical stabilization using bacteria is considered to improve the strength and reduce swelling behaviour by mixing different dosages of Bacteria to selected soil and waiting for different curing periods. The methodology is used for induction of microbes into selected soil and inspect the strength, based on the results of Unconfined Compressive Strength(UCS). The mechanism that occurred is analyzed using Scanning Electron Microscope (SEM) studies. Bacteria is isolated from vegetable peel waste and induced to the selected soil for finding variation in the strength of soil so as to ascertain the optimum dosage for bacteria induction and curing time for better strength improvement. The test results show an intensification of the strength of the soil as a result of the process of enzymatic Calcium Carbonates (CaCO3) precipitation.