Bio-Cement and Bio-Cementation Process

Today most of building materials are extracted  from non renewable source which contribute huge amount into CO2 emission into atmosphere. Innovation are required in building materials and techniques to achieve the goal of Sustainable Development and reduce the CO2 emission. The evidence of micro organisms involvement in calcium carbonate leads to development of Bio cement.

The activities of microorganisms produces a  deposit of Calcium Carbonate (CaCO₃) in bulk form or in small crystal form. These deposited CaCO₃ is known as Bio Cement or microbal induced carbonate precipitation (MICP).

Advantage of Bio Cement

• The production of Bio cement is slightly different process which needs a much shorter time for production.
• The raw material of bio cement can be produced at low temperature, much efficient than ordinary cement which needs 1500˚C temperature in production process.
• Bio cement can be used as eco construction material since it consume less energy and less CO2 emission in the production process as compared to other ordinary cement. 
• It increases compressive strength of mortar by up to 38 percent.
• Bacteria in Bio Cement consumes all oxygen inside the reinforced structure and reduce the internal corrosion.
• The bacteria is not harmful for human. 

Bio Cementation Process

The process to produce Bio Cement involve MICP(microbal induced carbonate precipitation) process. The microorganism has a special ability to create an alkaline environment (high pH and DIC increase) through their various physiological activities. Three main groups of microorganism that can induce the carbonate precipitation are - (i) photosynthetic microorganism such as cyano-bacteria and microalgae; (ii) sulphate reducing bacteria; and (iii) some species

of microorganism involved in nitrogen cycle. Photosynthetic microorganisms utilize urea using urease or urea amidolyase enzyme, based on which it is
possible to use microalgae as media to produce bio cement through bio cementation.
The patent method of producing Bio-Cement is shown in below figure

The Cementation process takes place in pipes. These pipes are filled up of sand and Urea/calcium and bacteria culture is mixed in tank and then sprayed into pipes several times until the sand in pipes are fully saturated. The process take 24 hours to complete the reaction and then produced mixture is dired in 60°c  and grind properly to get fine powder.
Mortar is generally made of a binder (Cement) or fine aggregate. Similarly the biological mortar made up of three main components- limestone, nutritent and bacteria paste.

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