Biotechnological approach for enhancing the properties of mortar using treated wastewater

Abstract

Remediation of pores and cracks to prevent ingress of moisture in cement mortar can be done through microbially induced precipitation of calcium carbonate using tap water as mixing water. However, limited research is available for doing this with wastewater. This paper reports on research using treated wastewater to develop a biotechnological mortar by inoculating calcium carbonate-precipitating bacteria isolated from the waste medium. This resulted in an enhancement of 27% in compressive strength and 11% reduction in water absorption compared with a control mortar at 28 d. Advanced analysis with scanning electron microscopy, X-ray diffraction, rapid chloride permeability test and ultrasonic pulse velocity test was conducted to provide a deeper understanding of how the resulting wastewater ‘bio-mortar’ was improved.