Improvement in Properties of Bulk and Surface Concrete by Using Bacteria

Abstract

There are number of techniques that can be used to increase strength and durability of a concrete structure. Microbial treatment is latest and found out to be effective among all the techniques.Mcirobial concrete is a revolution metabolic by product of microbially induced calcite precipitation with the help of urease, which is a hydrolyzing enzyme, gives a hopeful research in biotechnology and civil engineering for the enrichment of strength and durability of a building material and reinforced concrete structures. The main focus of this present research work is to set up an efficient, cost-effective and ecological process, which could improve strength and durability of concrete structures. At the same time the bacteria should not have any detrimental effect on the basic structure of concrete. Bacteria used for the biological process was extracted from fully alkaline atmosphere that is by using calcium hydroxide which is the main source of cement so that the grown bacteria can easily survive in alkaline environment. In this research Bacillus bacteria which are a strain of CT-5 were inoculated from cement source. The inoculated bacterium was used with nutrient broth, urea and calcium source to make bacterial culture. The culture so obtained was mixed with basic ingredients of concrete to obtain microbial concrete. Bacteria is added to concrete at different stages of its formation, in order to check its efficacy when used in making of fresh concrete or as repair strategy of old concrete. The addition of bacteria is found out to very effective in increasing the strength and durability of concrete. The compressive strength of the microbial concrete was monitor at 3, 7 and 28 days. The powdered sample was further obtained from the crushed specimen that was used to perform pH, EDTA, SEM-XRD for each case. About 60% of increase in compressive strength was observed by microbial treatment. Different tests have also confirms presence of calcium carbonate precipitation. Further the following approach has also found out to be efficient in reducing water permeability in concrete structure.