Engineering experimental study on the mechanical and durability properties of concrete by partial replacement of cement with microbially induced calcite precipitation (MICP) bio-cement

Concrete has become an indispensable component in construction due to its high efficiency, easy of mixing to meet a variety of special needs, and ability to be formed to virtually any shape. However, despite its numerous desirable qualities, concrete has several drawbacks that need improvement, such as weak and porous interfaces making it prone to micro cracking, significant energy usage, and environmental risks. Therefore, this study aimed to investigate the effects of Microbially Induced Calcite Precipitation (MICP) in enhancing the strength, reducing the permeability of concrete, and goal to minimize cement use. The study involved soil sampling, bacteria isolation, and fermentation to produce bio-cement added to concrete in different ratios. An experimental study design was used to investigate the effect of six levels of selected MICP: 0, 20%, 40%, 60%, 80%, and 100% by wt on the workability, density, compressive strength, Strength Activity Index, tensile strength, permeability, and flexural strength of concrete. The study showed that the addition of bio-cement significantly improved the density of conventional concrete by 0.7%, compressive strength by 33.7%, tensile strength by 20%, permeability by 46.65%, and flexural strength of concrete by 6.8%. From the study findings, it was concluded that the addition of bio-cement can improve the permeability and strength of concrete up to a certain extent with the best improvement achieved at 60% bio-cement content. The research introduced a novel, sustainable, cost-effective, and environmentally friendly biomaterial for construction that demonstrated superior performance.