Use of bacteria to improve electrical resistivity and chloride penetration of air-entrained concrete

Abstract

Abstract Use of bacteria in concrete is an eco-friendly technique to enhance concrete durability. Since the concrete is a dry and alkaline medium, the present study implemented air-entrained concrete to protect bacteria against this harsh environment. For this purpose, electrical resistivity experiments were conducted using 90- and 120-days old concrete specimens. Rapid chloride permeability tests were also performed on 90-days specimens. The experiments were designed using fractional factorial split plot (FFSP) to decrease the number of tests while the results remain reliable. Results obtained based on FFSP statistical analyses indicated that inclusion of bacteria enhanced the electrical resistivity and reduced the chloride permeability of concrete. Even better results were achieved with high air content percentages since the bacteria exhibited a better performance near the air voids. Furthermore, it was shown that surface treatment with bacteria increased concrete electrical resistivity and further reduced its chloride penetration for specimens cured in a medium containing minerals. In addition, lower porosity was observed in scanning electron microscopy (SEM) analysis when the specimens contained bacteria.