Title: Flexural Strength Recovery Induced by Vegetative Bacteria Added to Mortar

Author(s): Sarah L. Williams, Nazmus Sakib, Mary Jo Kirisits, and Raissa D. Ferron

Publication: Materials Journal

Volume: 113

Issue: 4

Appears on pages(s): 523-531

Keywords: bioinspired; biomineralization; calcium carbonate; flexural strength; self-healing; strength recovery

DOI: 10.14359/51688831

Date: 7/1/2016

Abstract:
Recent interest has focused on developing a bioinspired, selfhealing concrete in which microorganisms induce calcium carbonate precipitation to repair cracks. Although initial studies in this area have produced promising results, the ability of such microorganisms to restore structural integrity to the material through the recovery of mechanical properties (for example, strength and stiffness) has not been fully addressed. Previous studies have focused primarily on the self-sealing (that is, crack closure) of cracks as indicated by visual observation, ultrasonic test methods, or water permeability. While crack-sealing in concrete is certainly beneficial for durability, a true self-healing concrete should restore structural integrity by providing strength recovery. In the current study, the efficacy of various bacteria-based repair agents for cracked mortar beams was evaluated. Precracked mortar beams subjected to various bacterial treatments exhibited greater flexural strength recovery (8 to 30% recovery) as compared to that of precracked mortar beams without bacteria (3 to 5% recovery).