Protection of concrete structures under sulfate environments by using calcifying bacteria

Abstract

Abstract Application of microbial induced calcium carbonate precipitation (MICP) via biomineralization process has been considered as a novel method in improving durability properties of concrete. This bio-based treatment had been extensively targeted to improve the overall performance of concrete at lab scale experiments. Durability of microbial treated concrete under aggressive environments is still unexplored. In the current study, the durability properties of microbial treated concrete structures were studied after exposure to chemical and physical sulfate salt solutions (5% Na2SO4 and 5% MgSO4). It has been observed that sulfate attack damaged the untreated concrete specimens causing ultimate failure due to expansion under both exposure regimes. Thick salt efflorescence and severe surface scaling was observed in untreated mortar during physical sulfate attack. However, specimens treated with bacteria (Bacillus sp. CT5) significantly improved the resistance towards sulfate ingress. The experimental results indicate the extensive reduced expansion rate, salt efflorescence and surface scaling in bacterial treated concrete in sulfate exposure. The present study results indicates the potential of this technology in the overall improved resistance of microbial concrete against sulfate environment.