A review and study on the effect of bacterial factors in reducing the permeability and increasing the strength of concrete

The components of concrete and their composition play a decisive role in explaining the mechanical properties; However, some factors aggravate the weak durability and integrity of concrete. Pores in concrete are considered as one of the most important factors that knowledge of concrete repair methods can effectively protect concrete structures or increase their strength and stability and use in other industries such as water purifiers and a number of surface coatings. The development of cracks, owing to a relatively lower tensile strength of concrete, diverse loading, and environmental factors driving the deterioration of structures, is an inescapable key concern for engineers. Reparation and maintenance operations are thus extremely important to prevent cracks from spreading and mitigating the lifetime of structures. However, ease of access to the cracked zone may be challenging, and it also needs funds and manual power. Hence, autonomous sealing of cracks employing microorganisms into the concrete sans manual intervention is a promising solution to the dilemma of the sustainable improvement of concrete. ‘Ureolytic bacteria’, key organism species in rumen-producing ‘urease’ enzymes such as Bacillus pasteurii or subtilis—when induced—are capable of producing calcium carbonate precipitations into the concrete. As their cell wall is anionic, CaCO۳ accumulation on their surface is extensive, and the whole cell, therefore, becomes crystalline and ultimately plugs pores and cracks. This natural induction technique is an environmentally friendly method that researchers are studying intensively. This manuscript reviews the application process of bacterial healing to manufacture autonomous self-healing bacterial concrete. Additionally, it provides a brief review of diverse attributes of this novel concrete which demonstrate the variations with the auto-addition of different bacteria, along with an evaluation of crack healing as a result of the addition of these bacteria directly into concrete or after encapsulation in a protective shell

کلیدواژه ها:

self-healing ، concrete ، bacteria ، autonomous curing ، cracks ، strength ، durability ، sustainability ، microstructure