Concrete is a vastly used building-material in the globe. It has low tensile strength, so it is prone to cracking. The strength and durability of the concrete structures turn down because of cracking in concrete and expose of steel bars to the outside environment. Thus it is necessary to control crack width to improve the service life of the concrete structures. The microbial mineral precipitation is a novel technique used to enhance the quality of concrete by precipitation of calcium carbonate. The method of Calcite Precipitation by bacteria in concrete is more desirable because it is pollution-free and natural. This paper briefly describes the different types of microorganisms, its genetic constituents, different factors affecting the calcite precipitation in concrete. It gives a short explanation about the different ways of incorporation of bacteria into the concrete and consequence of calcite precipitation by microbes on the properties of the concrete. It also presents an inclusive report on the different kinds of bacteria used by researchers with its optimum concentration to develop the overall quality of the concrete. It is summarized that which type of bacteria was highly utilized in the past by the researchers to improve the compressive strength, water absorption and permeability of the concrete. At last, the literature shows that the direct application of bacteria in concrete can be used to improve the strength and durability properties of concrete.

Bacteria, Bacterial Concrete, Biomineralization, CaCo3 precipitation, Calcite precipitation, Compressive strength, Concrete, Durable Concrete, Mineral precipitation

The motivation behind the completed literature survey was to go through the accessible literature on uses of organisms to encourage calcite in concrete and cement mortar. Microorganisms can be applied to concrete and mortar in two different ways; (1) Direct application and (2) By encapsulation techniques. We have uniquely centered around the literature identified with the direct applications of organisms to improve the mechanical properties and durability of the concrete. The majority of the investigations in the writing demonstrate that Sporosarcina pasteurii and Bacillus megaterium are the fittest species for calcite precipitation in mortar or concrete. Endeavors might be made to find or grow new strains of this or different species with better calcification efficiencies and flexibility to process conditions for various applications. The literature survey has checked on various kinds of microscopic organisms, its morphology, different polymorphs of calcite and the various clusters of microorganisms associated with calcite precipitation. The effect of Culture media, the concentration of microorganism’s cell, substrate, calcium sources, and the surrounding environment during the process of microbial mineral precipitation has been fundamentally investigated. As may be recognized from the investigation of the literature, less importance has been given to the effect of culture medium on microbial mineral precipitation, biochemical reaction between cement and chemical sources. Before the field application of microbial mineral precipitation, it is equally important to know the optimize quantity of substrates and calcium sources used for the process microbial induced calcite precipitation in concrete or mortars. At present the underlying expense of production, revival, and addition of microorganisms into the mortar or concrete is high. There might be two potential approaches to make it suitable for the construction industry; by decreasing the expense of isolation, storage, and revival of bacteria and by increasing the life of the structure as a result of improving its durability through the process of microbial induced mineral precipitation. We can minimize the expenses that occurred on the maintenance of a reinforced concrete structure by adapting this technique. White et al., [91] clarified it by performing some experiments on life cycle expenses of concrete structure and concluded that in some cases the expenses involved in repair and rehabilitation of concrete structure might exceed the initial construction cost. Quality parameters of concrete other than strength like Shrinkage, erosion, carbonation properties and changes in the biochemical reactions of calcite precipitation throughout various phases of cement hydration and its belongings on the characteristics of concrete or mortar are yet to be studied in detail. Its proficiency in securing bigger size structural members should be tried further under non-perfect temperature ranges, high salty atmosphere, etc. for a longer period of time. Likewise, the issue of enhancement of supplement media should be tended to. At long last, details and test guidelines ought to be created to evaluate microbial concrete execution in structures and its usage in concrete structure might be expected in the future. The mechanism and the biochemical reaction by an enzyme urease to create calcite precipitation were audited profoundly through various sources of literature. This study recognized that microorganisms positively affect the compressive strength of the cement mortar and concrete. The investigation has likewise concluded that it diminishes the permeability by deposition of calcite. The present literature survey prescribes that the concrete using microbes has the potential to be a substitute and high-class concrete which is economical, natural, and in the end-use for the improvement in the durability of concrete structure materials.

Vaghela, K.B. and Pitroda, J.R. (2019). Microbial Mineral Precipitation to Develop the Properties of the Concrete – A Review. International Journal on Emerging Technologies, 10(4): 335–344.