The adaptability of Sporosarcina pasteurii in marine environments and the feasibility of its application in mortar crack repair

Abstract

Existing studies focus mainly on how Sporosarcina pasteurii can effectively repair concrete cracks in freshwater environments, but they rarely discuss the influence degree and functional mechanism of seawater salinity on the growth and mineralization of the bacterium and its repair effect on concrete cracks. This work compared the growth and mineralization characteristics of the bacterium under two extreme salinity conditions (freshwater and seawater) and the self-healing behaviour of cracks after the bacterium was mixed with mortars. The results showed that the salinity of the seawater changed the morphological structure (from rod to oval) of the bacterium, reduced its growth rate, inhibited its mineralization behaviour, and slightly reduced the self-healing efficiency of cracks in mortars with the bacterium loaded with diatomite. Nonetheless, the bacterium survived and mineralized in the seawater, and it induced calcium carbonate precipitation to effectively fill cracks (the self-healing rate was over 80% after 15 days of healing), reducing the permeability of water flow through the cracks. The research results help us comprehensively understand the mineralization of the bacterium, are of reference value for its potential microbially induced carbonate precipitation (MICP) application in marine environments, and have important engineering significance for improving the durability and service life of coastal concrete structures.