A review on utilization of pozzolanic materials in microbial concrete

Microbial calcite precipitation has been intensively studied recently for the improvement of compressive strength and durability of concrete, including those with pozzolanic materials such as metakaolin (MK), fly ash (FA), and silica fume (SF). Such materials possess high pozzolanic activity and have become an essential part of high strength and high performance concrete mix design. However, when replacing cement at high proportion, it has been found that such materials can cause a decrease of freeze-thaw resistance and early age strength of concrete. To remedy the defects, microbial calcite precipitation, a continuous extracellular cementation process dominated by bacteria, has been used to improve the engineering properties of such concrete. This article gives an overview of the biocementation process for the improvement of compressive strength and durability of concrete where cement was partially replaced with mk, fa, and sf. It has been found that properties like compressive strength, and durability of pozzolanic concrete can be improved with microbial calcite precipitation.