Influence of <i>Pondus hydrogenii</i> on Self-Healing and Permeability Properties of Bio-mortar

ABSTRACT Strength and durability characteristics of cementitious composites using microbiologically induced calcite precipitation were studied. The microbe used in this study was isolated from concrete debris in the soil and identified as Bacillus paramycoides. The novelty of this research lies in it exploring the permeability reduction and healing efficiency of the isolated species in mortar specimens, cured in various Pondus hydrogenii (pH) and adjusted in a pH range from 3 to 13. After 7 days of curing, the specimen was precracked manually to a crack width of less than 1 mm and cured in water with an adjusted pH. Higher healing percentages were noticed for specimens to which Bacillus paramycoides was added and cured at pH 6, pH 7, and pH 8. A water permeability test was conducted for specimens at regular intervals to study healing in the matrix pores. Permeability was reduced by 82 % in samples cured in water with pH ranging from 6 to 8. X-ray diffractometer analysis indicated the presence of calcite, aragonite, and vaterite compounds. Investigation with a scanning electron microscope revealed the existence of calcium carbonate compounds and traces of bacteria. Overall, the cost of maintenance and repairs was likely to decrease. This will help to minimize greenhouse gas emissions and advance the development of sustainability in construction industries.