The evaluation of the impact of nutrients on the bio-based self-healing concrete compressive strength

Abstract

This paper investigates the composition of the nutritional part of the biological selfhealing agent based on its impact on the compressive strength. A direct addition of the agent a mixture of bacterial spores and nutrients – into concrete matrix has been investigated by many studies in recent decades. Under certain conditions, the applied microorganisms proved to be able to produce CaCO 3 , and researchers used this biocalcification process to autonomously seal microcracks in concrete. However, it has been shown that the self-healing agent, especially the indispensable nutrients, can positively or negatively influence the material characteristics. In this study, some of the most suitable and frequently proposed nutrients were directly added into cement mortar during the mixing process and their impact on the compressive strength was evaluated. Results show that calcium nitrate, calcium formate, calcium lactate, and urea have generally a potential to increase the compressive strength, especially in early ages. In contrast, the applied dose of yeast extract resulted in a drastic drop of compressive strength, thus further optimization of the concentration will be probably needed.