Bacterial species impact on self-healing of cement based materials in marine structures

Despite concrete being inherently strong and resilient, durability issues stemming from undesirable cracks can significantly reduce the lifespan of concrete structures or cause costly maintenance and repair procedures. Accordingly, the phenomenon of self-healing holds crucial importance in preserving the longevity of existing buildings. This study particularly focused on utilizing two seawater tolerant bacteria, Marinobacterium litorale, and Halomonas elongata, in cementitious systems to experimentally investigate their overall performances and self-healing capabilities. Bacillus subtilis and Bacillus megaterium, which had proven effective in earlier studies, were used as controls. To gain insight into the self-healing potential of bacterial strains, a comprehensive experimental program including flow table, compressive strength, flexural strength, ultrasonic pulse velocity, and capillary permeability tests were performed. Furthermore, the extent of self-healing was assessed using a digital camera to measure crack closure rates, and the healing products formed within cracks were characterized through FE-SEM-EDX, and XRD. Based on crack closure observations, mixtures containing M. litorale and H. elongata demonstrated superior self-healing performance, particularly in salt water environments. Consequently, both M. litorale and H. elongata exhibited promising mechanical and permeability performance, showcasing similar effectiveness to popular Bacillus strains.