Analysis of the Current State of Research on Bio-Healing Concrete (Bioconcrete).

The relatively small tensile strength of concrete makes this material particularly vulnerable to cracking. However, the reality is that it is not always possible and practically useful to conduct studies on high-quality sealing cracks due to their inaccessibility or small opening width. Despite the fact that currently there are many technologies for creating self-healing cement composites, one of the most popular is the technology for creating a biologically active self-healing mechanism for concrete. It is based on the process of carbonate ion production by cellular respiration or urease enzymes by bacteria, which results in the precipitation of calcium carbonate in concrete. This technology is environmentally friendly and promising from a scientific and practical point of view. This research focuses on the technology of creating autonomous self-healing concrete using a biological crack-healing mechanism. The research methodology consisted of four main stages, including an analysis of the already conducted global studies, ecological and economic analysis, the prospects and advantages of further studies, as well as a discussion and the conclusions. A total of 257 works from about 10 global databases were analyzed. An overview of the physical, mechanical and operational properties of bioconcrete and their changes is presented, depending on the type of active bacteria and the method of their introduction into the concrete mixture. An analysis of the influence of the automatic addition of various types of bacteria on various properties of self-healing bioconcrete is carried out, and an assessment of the influence of the method of adding bacteria to concrete on the process of crack healing is also given. A comparative analysis of various techniques for creating self-healing bioconcrete was performed from the point of view of technical progress, scientific potential, the methods of application of this technology, and their resulting advantages, considered as the factor impacting on strength and life cycle. The main conditions for a quantitative assessment of the sustainability and the possibility of the industrial implementation of the technology of self-healing bioconcrete are identified and presented. Various techniques aimed at improving the recovery process of such materials are considered. An assessment of the influence of the strength of cement mortar after adding bacteria to it is also given. Images obtained using electron microscopy methods are analyzed in relation to the life cycle of bacteria in mineral deposits of microbiological origin. Current gaps and future research prospects are discussed.