The dissertation was defended at the public meeting of the Dissertation Defence Council of the Scientific Field of Materials Engineering in the Aula Doctoralis Hall of Vilnius Gediminas Technical University at 1 p.m. on 7 February 2025.
This dissertation investigates the effect of Bacillus genus bacteria immobilised in different carriers on concrete and their viability in alkaline environments. The dissertation aims to select the composition of biological concrete that ensures the viability of the bacteria and to investigate the closure of cracks in it under laboratory conditions. Ensuring bacterial viability in biological concrete could allow such structures to last longer and reduce maintenance costs. The dissertation approaches several objectives, such as investigating the influence of cement composition and environmental factors on the viability of different types of bacteria in biological concrete, selecting the most suitable bacterial carrier, and investigating the crack closure ability of the concrete. These tasks are formulated considering that one of the significant challenges in developing biological concrete is ensuring the long-term viability of the incorporated bacteria. The dissertation consists of an introduction, three chapters, General Conclusions, References, lists of publications on the topic of the dissertation, Recommendations, and Summary in English. The introduction presents the problem under investigation, the relevance of the dissertation, and the research object. It formulates the purpose and tasks, research methodology, scientific novelty, the practical significance of results, and defended statements. The introduction ends by presenting the author’s publications on the subject of the dissertation, information on presentations at scientific conferences, and describes the structure of the dissertation. The first chapter revises the used literature. This chapter describes the pathways of bacterial CaCO3 precipitation, reviews the carriers that can be used to protect bacteria in biological concrete, and discusses the possibilities of using bacteria and other microorganisms in biological concrete. At the end of the chapter, conclusions are drawn, and the dissertation’s tasks are formulated. The second chapter presents the materials used in the study and describes the methods used to investigate the properties of cement pastes, the viability of bacteria in concrete and the self-closing of cracks. The third chapter presents bacterial viability studies in biological concrete using different bacterial species and carriers. It reveals the dependence of bacterial viability on cement types, cement hydration temperature, and environmental conditions. The efficiency of crack closure in biological concrete is also investigated. Four articles on the dissertation topic were published in scientific journals included in the list of Web of Science, and one was published in another peer-reviewed journal. Eight presentations on the topic of the dissertation were made at national and international conferences.
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