Performance enhancement of brick aggregate concrete using microbiologically induced calcite precipitation

Abstract

The use of brick aggregates is very common in Bangladesh and nearby regions as artificial aggregate replacing natural stone. To ensure sustainable construction, finding a way to enhance its durability is extremely necessary. Microbiologically Induced Calcite Precipitation (MICP) using indigenous urease positive bacteria collected from soil showed promising results in initial research, hence further investigation has been carried out for comprehensive understanding on the effectiveness of this method. Two incubation periods of 24 hours and 48 hours were considered for bacterial culture. Absorptiometric method was used to examine population growth of bacteria due to varying incubation period. Both Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) were used to identify the presence of CaCO3 due to bio-treatment. In addition to Rapid Migration Test (RMT), Rapid Chloride Penetration Test (RCPT) was conducted to evaluate reduction of concrete permeability due to application of treated brick aggregate. It has been found that 48 hours incubation was more effective than 24 hours incubation. The longer incubation resulted in almost twofold reduction in aggregate absorption test. Compressive Strength, RCPT and RMT of brick aggregate concrete resulting from 48 hours incubation showed 14%, 27% and 43% improvement over untreated brick concrete, respectively. Keywords: Brick aggregates, Durability, Incubation, Bacteria, MICP