Kunamineni Vijay

Bio: Kunamineni Vijay is an academic researcher from National Institute of Technology, Raipur. The author has contributed to research in topics: Physics & Properties of concrete. The author has an hindex of 4, co-authored 5 publications receiving 170 citations.

Effect of calcium lactate on compressive strength and self-healing of cracks in microbial concrete

Abstract: This paper presents the effect on compressive strength and self-healing capability of bacterial concrete with the addition of calcium lactate. Compared to normal concrete, bacterial concrete possesses higher durability and engineering concrete properties. The production of calcium carbonate in bacterial concrete is limited to the calcium content in cement. Hence calcium lactate is externally added to be an additional source of calcium in the concrete. The influence of this addition on compressive strength, self-healing capability of cracks is highlighted in this study. The bacterium used in the study is bacillus subtilis and was added to both spore powder form and culture form to the concrete. Bacillus subtilis spore powder of 2 million cfu/g concentration with 0.5% cement was mixed to concrete. Calcium lactates with concentrations of 0.5%, 1.0%, 1.5%, 2.0%, and 2.5% of cement, was added to the concrete mixes to test the effect on properties of concrete. In other samples, cultured bacillus subtilis with a concentration of 1×105 cells/mL was mixed with concrete, to study the effect of bacteria in the cultured form on the properties of concrete. Cubes of 100 mm×100 mm×100 mm were used for the study. These cubes were tested after a curing period of 7, 14 and 28 d. A maximum of 12% increase in compressive strength was observed with the addition of 0.5% of calcium lactate in concrete. Scanning electron microscope and energy dispersive X-ray spectroscopy examination showed the formation of ettringite in pores; calcium silicate hydrates and calcite which made the concrete denser. A statistical technique was applied to analyze the experimental data of the compressive strengths of cementations materials. Response surface methodology was adopted for optimizing the experimental data. The regression equation was yielded by the application of response surface methodology relating response variables to input parameters. This method aids in predicting the experimental results accurately with an acceptable range of error. Findings of this investigation indicated the influence of added calcium lactate in bio-concrete which is quite impressive for improving the compressive strength and self-healing properties of concrete.

Self-repairing of concrete cracks by using bacteria and basalt fiber

Abstract: Concrete is a most extensively used material in construction; however, cracks in concrete are unavoidable. There is a new technology that can heal the cracks by precipitated calcium carbonate called as microbial self-healing concrete which reduces the coefficient of permeability. The self-healing/self-repairing concrete with the addition of fibers can be used in construction industries to enhance the strength and durability of concrete. Fibers may reduce the crack width by bridging action and bacteria develop a filling material in that bridge portion. This improves the durability and strength of bacterial concrete. In the present study, four different mixes are prepared, namely normal concrete, bacterial concrete, fiber-reinforced concrete, and bacterial concrete, with the addition of fibers. The healing/repairing efficiency of concrete is measured in terms of electrical resistivity and compressive strength of concrete on pre-cracked samples and healed samples. Further, the results are correlated with the scanning electron microscope and energy-dispersive X-ray spectrometer analysis. The results and analysis that carried out show substantial enhancement in the durability and strength of concrete with the addition of fibers in bacterial concrete.

Experimental Study on Bacterial Concrete Using Bacillus Subtilis Micro-Organism

Abstract: Concrete is a homogenous mix in which the cracks are unavoidable. The seepage of water and other salts through the cracks makes concrete weaker and reduces its life. Further, corrosion of steel may also occur due to the seepage of water and salts which weakens the reinforcement in concrete. Hence, it is required to rehabilitate the concrete for economic life of structures. To remediate the cracks in concrete, an inherent biomaterial, a self-healing material, is developed using bacteria. Bacterial concrete is a technique which is highly desirable because the calcium carbonate precipitation is induced as a result of microbial activities that can heal the cracks itself. Provision of suitable conditions and calcium sources to the microbes, a few strains of microbes can prompt the precipitate the calcium carbonates in concrete. This precipitation capability has been evaluated in recent decades to justify the improvement in strength and durability properties of concrete. In this study, Bacillus subtilis bacteria was used and tested for suitability in concrete. This paper shows the impact of Bacillus subtilis bacteria on compressive strength, workability and self-healing of cracks in concrete. Results show that the addition of bacteria can increase the strength of the concrete. And the workability of bacterial concrete depends on the nutrient source, i.e. calcium lactate; addition of calcium lactate may increase the workability of concrete. However, bacteria cultures and spore powder place a minor role in workability of concrete. Both the cultured and spore powder bacteria are giving good results in healing of cracks.

A review of self-healing concrete for damage management of structures

Abstract: The increasing concern for safety and sustainability of structures is calling for the development of smart self-healing materials and preventive repair methods. The appearance of small cracks (<300 µm in width) in concrete is almost unavoidable, not necessarily causing a risk of collapse for the structure, but surely impairing its functionality, accelerating its degradation, and diminishing its service life and sustainability. This review provides the state-of-the-art of recent developments of self-healing concrete, covering autogenous or intrinsic healing of traditional concrete followed by stimulated autogenous healing via use of mineral additives, crystalline admixtures or (superabsorbent) polymers, and subsequently autonomous self-healing mechanisms, i.e. via, application of micro-, macro-, or vascular encapsulated polymers, minerals, or bacteria. The (stimulated) autogenous mechanisms are generally limited to healing crack widths of about 100–150 µm. In contrast, most autonomous self-healing mechanisms can heal cracks of 300 µm, even sometimes up to more than 1 mm, and usually act faster. After explaining the basic concept for each self-healing technique, the most recent advances are collected, explaining the progress and current limitations, to provide insights toward the future developments. This review addresses the research needs required to remove hindrances that limit market penetration of self-healing concrete technologies.

Recent Advances in Intrinsic Self-Healing Cementitious Materials.

Abstract: Self-healing is a natural phenomenon whereby living organisms respond to damage. Recently, considerable research efforts have been invested in self-healing cementitious materials that are capable of restoring structural integrity and mechanical properties after being damaged. Inspired by nature, a variety of creative approaches are explored here based on the intrinsic or extrinsic healing mechanism. Research on new intrinsic self-healing cementitious materials with biomimetic features is on the forefront of material science, which provides a promising way to construct resilient and sustainable concrete infrastructures. Here, the current advances in the development of the intrinsic healing cementitious materials are described, and a new definition of intrinsic self-healing discussed. The methods to assess the efficiency of different healing mechanisms are briefly summarized. The critical insights are emphasized to guide the future research on the development of new self-healing cementitious materials.

Bioinspired self-healing materials: lessons from nature.

Abstract: Healing is an intrinsic ability in the incredibly biodiverse populations of the plant and animal kingdoms created through evolution. Plants and animals approach healing in similar ways but with unique pathways, such as damage containment in plants or clotting in animals. After analyzing the examples of healing and defense mechanisms found in living nature, eight prevalent mechanisms were identified: reversible muscle control, clotting, cellular response, layering, protective surfaces, vascular networks or capsules, exposure, and replenishable functional coatings. Then the relationship between these mechanisms, nature’s best (evolutionary) methods of mitigating and healing damage, and existing technology in self-healing materials are described. The goals of this top-level overview are to provide a framework for relating the behavior seen in living nature to bioinspired materials, act as a resource to addressing the limitations/problems with existing materials, and open up new avenues of insight and research into self-healing materials.