A biological route for producing low energy binders

Abstract

Building materials almost certainly consist of some form of binders. Presently used binders, such as cement, consume a high amount of energy consumption in its manufacturing and transportation. This paper reports a biomimetic strategy for production of binders at ambient conditions based on microbially induced calcium carbonate precipitation (MICP). Microorganisms such as Sporosarcina pasteurii and Bacillus megaterium are used for precipitation of calcium carbonate on substrates such as concrete and brick. The deposition reduces permeability and corrosion in the substrate. The paper demonstrates the methods of increasing efficiency and cost reduction of the process. Effect of microbial action on strength, permeability of concrete, particularly near its surface, and ingress of moisture and chloride are discussed. Result of calcite deposition on reinforced concrete in terms of current passed when exposed to harsh corrosive conditions and Icorr is presented. Further, the role of MICP has been presented to develop highly efficient and durable soil-cement brick that requires very low embodied energy for production and also emit least CO2.The current work demonstrates that production of biocalcification by urease producing bacteria can at least partially replace the industrial binders and provide a more sustainable alternative