BACTERIAL CONCRETE: NEW INVENTION IN CONSTRUCTION

2016

The effect of water-borne contaminants on the durability of concrete is well-known and cracked concrete is more susceptible to permeation of these contaminants. An approach to autonomic self-healing of such concretes is the utilization of microbiologically-induced calcite-precipitation. This approach uses the metabolic activity of bacteria and biomineral precursors embedded within the concrete to form an inorganic material, usually calcite, as the healing compound. However, bacteria-based healing of concrete creates a number of scientific and engineering challenges at the biology-concrete technology interface. This paper provides a review of previous and on-going research on the use of bacteria-based self-healing of concrete in relation to the problems associated with the setting, hardening and carbonation of concrete and the problems associated with healing large cracks.

2016

Micro-cracks are the main cause to structural failure. One way to circumvent costly manual maintenance and repair is to incorporate an autonomous self -healing mechanism in concrete. One such an alternative repair mechanism is currently being studied, i.e. a novel technique based on the application of biomineralization of bacteria in concrete. The applicability of specifically calcite mineral precipitating bacteria for concrete repair and plugging of pores and cracks in concrete has been recently investigated and studies on the possibility of using specific bacteria as a sustainable and concrete –embedded self healing agent was studied and results from ongoing studies are discussed. Synthetic polymers such as epoxy treatment etc. are currently being used for repair of concrete are harmful to the environment, hence the use of a biological repair technique in concrete is focused. Recently, it is found that microbial mineral precipitation resulting from metabolic activities of favourab...

Crack formation in concrete is common, but a typical phenomenon related to durability. Percolation of cracks may lead to leakage problems or ingress of deleterious materials, causing deterioration of the concrete matrix or corrosion of embedded steel reinforcement. Durability can be enhanced by preventing further ingress of water and other substances. In recent years a bacteria-based self-healing concrete is being developed to extend the service life. A two component healing agent is added to the concrete mixture. The agent consists of bacteria and an organic mineral precursor compound. Whenever cracks occur and water is present the bacteria become active and convert the incorporated organic compounds into calcium carbonate, which precipitates and is able to seal and block cracks. This paper aims to review the development of bacteria-based self-healing concrete, introducing the proposed healing system. Different stages in the development are discussed, and some recommendations for further research are given.

2013

Micro-cracks are the main cause to structural failure. One way to circumvent costly manual maintenance and repair is to incorporate an autonomous self -healing mechanism in concrete. One such an alternative repair mechanism is currently being studied, i.e. a novel technique based on the application of bio- mineralization of bacteria in concrete. The applicability of specifically calcite mineral precipitating bacteria for concrete repair and plugging of pores and cracks in concrete has been recently investigated and studies on the possibility of using specific bacteria as a sustainable and concrete -embedded self-healing agent was studied and results from ongoing studies are discussed. Synthetic polymers such as epoxy treatment etc. are currently being used for repair of concrete are harmful to the environment, hence the use of a biological repair technique in concrete is focused. Recently, it is found that microbial mineral precipitation resulting from metabolic activities of favour...

The service life of the structure have reduced in today's construction field due to the low durability, strength factors and various other properties of concrete structures exposed to the environment. A novel strategy to restore or remediate cracks formed in the structures is bio-mineralization of Calcium Carbonate using microbes such as Bacillus. This research gives the information about increasing the durability of the concrete structure by introducing bacterial cell and other required nutrients for the process of bio-calcification where the microorganisms secrete Calcium Precipitate which in the presence of Carbonate ion forms Calcium Carbonate(Calcite) layer thus self-healing the cracks. Thus the durability of the concrete structure will increase and a study has to be carried out with concrete cubes subjected to bacterium.

Ecological Engineering, 2010

The application of concrete is rapidly increasing worldwide and therefore the development of sustainable concrete is urgently needed for environmental reasons. As presently about 7% of the total anthropogenic atmospheric CO 2 emission is due to cement production, mechanisms that would contribute to a longer service life of concrete structures would make the material not only more durable but also more sustainable. One such mechanism that receives increasing attention in recent years is the ability for self-repair, i.e. the autonomous healing of cracks in concrete. In this study we investigated the potential of bacteria to act as self-healing agent in concrete, i.e. their ability to repair occurring cracks. A specific group of alkali-resistant spore-forming bacteria related to the genus Bacillus was selected for this purpose. Bacterial spores directly added to the cement paste mixture remained viable for a period up to 4 months. A continuous decrease in pore size diameter during cement stone setting probably limited life span of spores as pore widths decreased below 1 m, the typical size of Bacillus spores. However, as bacterial cement stone specimens appeared to produce substantially more crack-plugging minerals than control specimens, the potential application of bacterial spores as self-healing agent appears promising.

Crystals

Cracking is one of the main ways that concrete ages, allowing pollutants to seep within and potentially lowering the physical and mechanical strength and endurance of concrete structures. One of the healing procedures that merits research is the use of bacterially generated calcium carbonate precipitation in concrete mixtures to mend concrete cracks. The impact of different variables, including the nucleation location, bacterial type, concentration, uratolytic activities, pH, nutrition, and temperature on the bio-mineralization of calcium carbonate are discussed in this review article. ATR-IR (Attenuated Internal Reflectance Fourier Transform Infrared Spectroscopy)/FTIR (Fourier Transform Infrared Spectroscopy)/NMR (Nuclear Magnetic Resonance) and FESEM (Field Emission Scanning Electron Microscope) are among the micro test techniques reviewed along with the biosynthetic pathway of bio mineralized calcium carbonate. The sealing ability and recovery of mechanical and durability proper...

2019

Concrete is an extensively used building material used for construction works. It is well known that one of the weaknesses of concrete is its vulnerability to cracking. Cracks may occur when concrete is in a plastic state or after it has completely hardened. Micro cracks in concrete also affect durability by allowing ingress of corrosive substances into the concrete matrix, which lead to corrosion of steel and loss in tensile strength. Such occurrence may lead to more adverse problems such as spalling and even premature structural failure. Repair and maintenance of concrete structures are labour and capital intensive. It is difficult to access the degree of damage after the construction is completed. Self-healing is a possible solution. There are many approaches of self-healing such as Autogenous and Autonomous Self-Healing. Bacteria-induced mineral precipitation is an environmentally friendly technology to enhance the self-healing ability of concrete cracks. The objective of this p...

International Journal of Engineering Research and, 2020

Cracks in concrete are unpreventable and it is intrinsic weakness of concrete. Through these cracks water and salts can seep. It initiates corrosion further reducing the life of concrete. So there was a requirement to develop an intrinsic biomaterial, a self repairing technique which can repair the cracks and fissures developed in concrete. This technique is highly desirable because the activity of crack remediation is eco friendly and natural. The paper discusses the plugging of artificial cracks in in cement concrete using Bacillus megaterium. The effect on compressive strength, water absorption and water permeability of cement concrete cubes due to mixing of bacteria is also discussed in this paper. It was found that the use of Escherichia coli improves the compressive strength and stiffness of concrete. The effect on compressive strength, water absorption and water permeability of cement concrete cubes due to mixing of bacteria is also discussed in this paper. It was found that the use of Escherichia coli improves the compressive strength and stiffness of concrete. It also shows that there is reduction in water absorption and water permeability when compared to conventional concrete. The bacteria which are going to be introduced in concrete should have the properties of alkali resistance and it also should form endospore, so that it can withstand the stresses produced in concrete while mixing, handling and transporting.

Journal of Advanced Concrete Technology, 2019

Recent studies in the field of concrete materials show that the early cracking criteria in micro-size can occur as soon as the cement matrix becomes hardened. In many ways, these cracks can become macro-size and opened cracks resulting in significant issues for the durability and appearance of concrete structures as water leakage and corrosion. The technique of self-healing using bacteria has recently received attention for its potential applications. However, the effectiveness and the repeatability of this method over a long period have not been clarified. The information on both the survival and the number of bacteria after healing is limited. This paper aims to improve the self-healing ability and repeatability of concrete when using Bacillus subtilis natto. The experimental studies evaluate the effect of biomineralization with lightweight aggregate as the protecting-carrying vehicle, which can control the release of healing fluid through four cracking-healing cycles. The urease activity and the biomineralization of the bacteria with urea as the main carbon source were assessed and the effect of cracking age on the self-healing capacity, associated with the compressive strength improvement was studied. The results obtained from the optical microscope and SEM/EDS analysis indicated the existence of bacteria CaCO 3 forming in concrete after four healing cycles. During long duration, bacterial concentration in concrete was determined by microscopic counting method. Based on experimental results, the restoration of the compressive strength confirmed the high self-healing ability of concrete when using bacteria in lightweight aggregate.