This Early-Concept Grant for Exploratory Research (EAGER) project intends to carry out a preliminary evaluation of the potential of biomineralization in cementitious materials for self-healing of cracks. The main objectives are to examine the survival and effectiveness of the chosen microorganisms in concrete, and to evaluate the effects of carbonate deposition on crack remediation. Microorganisms induced carbonate deposition will be studied in simple test tube experiments and in mortar specimens. Scanning electron microscopy and X-ray diffraction will be used for detailed characterization of the deposits and to investigate if enough carbonate deposition can be achieved to fill up cracks. Fracture study will be performed to evaluate if carbonate deposits can promote regain of fracture toughness.
Quasi-brittle nature of concrete and its tendency to crack makes maintenance of concrete structures a costly and labor intensive process. Thus research has been undertaken worldwide to develop a smart infrastructure material which can heal cracks. However, the perfect material that satisfies this need is yet to be developed. In recent years it has been reported by few researchers that bio-mineralization technique is promising based on its effect on compressive strength. However, increase in compressive strength is not a sufficient proof that the bond between newly developed carbonate and cracked material is sufficient to regain part of the strength lost due to cracking. This EAGER proposal carefully develops an experimental plan to evaluate potential of bio-mineralization. If this preliminary study shows promise it could pave the way for future work on biomineralization to establish a transformative concept of self-healing construction materials.
Quasi-brittle nature of concrete and its tendency to crack makes maintenance of concrete structures a costly and labor intensive process. The goal of this EAGER project was to explore the idea of developing self-healing concrete by mimicking natural process of limestone deposition. Metabolism of certain microorganisms in presence of calcium promotes calcium carbonate deposition, which is called biomineralization. It supposedly plays an important role in the limestone deposition in nature. This project intended to carry out a preliminary evaluation of the potential of biomineralization in cementitious materials for self-healing of cracks. If, microorganisms induced carbonate deposition within cracks is enough, cracks can be filled up. This could lead to reduction in porosity and hence improvement in concrete durability. However, in order to recover strength of cracked concrete fully or partially, the filling material needs to bond well with the old material. Therefore, the main objective of this project was to explore if microorganisms induced carbonate deposition can promote crack remediation in concrete. In this project, a multidisciplinary team worked together to bring the expertise in cementitious materials and microbiology together and promoted collaboration among different areas within civil engineering. This project helped a graduate student learn and implement concepts of microbiology and concrete materials together, which is unique. Results of this project confirm that biomineralization can be used to develop self-healing cementitious materials. Once developed fully, this research has promise to reduce life cycle cost and energy consumption associated with maintenance of concrete structures.
