Investigation of the effect of urease bioadditives on porosity and water absorption of cement composites

The results of the application of the biomineralization process in concrete to improve concrete properties such as porosity and water absorption are presented. As a result of the research, an assessment of the activity of various bioadditives based on the Bacillus subtilis strain and isolates isolated from samples of chernozem soil of the Yelets district of the Lipetsk region was given.It was found that the immobilized bacteria slightly differ from the native form in terms of urease activity, however, when stored for more than 50 days. they maintain their activity at a high level, and native microorganisms lose their ability to function, reducing urease activity by 10 times practically to minimum values. It was also revealed that when using Portland cement of various types, there is a decrease in water absorption up to 30%, and porosity decreases up to 40%.The use of different types of fine aggregate also affects porosity, so when using the same parts of sand P1 and P2, porosity is lower than with a homogeneous fine aggregate.It was also noted that all samples had increased strength characteristics – compressive strength and bending strength by 15–25%, respectively. Thus, the use of bioadditives is optimal to achieve improved concrete characteristics.