Expanded polystyrene (EPS) particles as a carrier to improve the growth of microorganisms in concrete

Abstract

At present, microbial-induced carbonate precipitation (MICP) is still difficult to apply to cement and concrete, mainly because bacteria are easily corroded by alkaline cement. However, the carrier commonly used in engineering is expensive and difficult to be obtained. To solve the noted problem, this study reports an economic and environmentally friendly carrier to carry microorganisms, namely waste expanded polystyrene (EPS) particles. This work aims to investigate the potential of EPS particles as a biocarrier applied to the concrete. A series of tests were used tests were used to characterize the biocement samples with EPS particles, and the samples were analyzed for strength, pore distribution, and density. The results show that EPS particles as the carrier can improve the biomineralization by 5.85–17.79% and the pore distribution of concrete. The porosity and self-supporting of EPS can adsorb microorganisms inside or on its surface, thus avoiding the microorganisms from being eroded by highly alkaline concrete. The OD600 value increased by 0.45 when EPS particles are added. Many CaCO3 and hydration products are generated on the surface of EPS particles, which improves bacterial growth and also proves that EPS particles are not mutually exclusive with cement. EPS particles in the samples cured for 28 days are still intact and not decomposed by bacteria. The cost of the EPS carrier is 80% lower than that of the common carrier, such as diatomaceous earth and microcapsules, but the strength of the sample decreases because EPS is a lightweight material. This is of great significance to the utilization of solid waste and the development of biotechnology.