Bio-sintering of Limestone to Produce Pollution Free Cement

Abstract

Industrial cement is produced by consuming too much energy and emitting very high CO2. Nature too produces cement, but it is pollution-free. This research demonstrates an emulation of natural cement by bio-sintering limestone, a process of successive dissolution and reprecipitation of limestone with the help of bacteria in ambient environmental conditions. When the bacteria Acetobacter aceti were introduced into a mixture of ethanol and limestone powder, the pH came down rapidly, and dissolution of limestone into calcium acetate was observed. After the ethanol was fully consumed, the pH rose gradually, and biocement crystals were reprecipitated. All the reaction rates have been determined, and the products have been characterised. It is observed that the morphology of the biocement could be tailored by controlling the reprecipitation process. The dissolution and reprecipitation took place within the time scale of present construction methods. Thus, this process can potentially manufacture industrial cement from limestone sans the pollution.