Self Healing Cement

A Bacteria can do Wonders for Cement Industry

Cement, as you can relate to while constructing homes. Mason lays the bricks, put some cement on that and then lays another layer of bricks. With time, after the curing process, the bricks get stuck to each other permanently with good strength.
From where does this cement came from ?
First time the world came across this word in 1824. Cement was first developed by Joseph Aspdin in his kitchen. An enterprising 19th-century British stonemason heated a mix of ground limestone and clay in his kitchen stove, until the mixture calcined and finally grinding it into a fine powder. The result was the world's first hydraulic cement, one that hardens when water is added.

Today, Cement Industry is one of the largest industries of the world. It ranks next to steel in construction material and so is the basis of all modern construction. It is the same material that is cursed the most for the cause of environment deterioration. The high temperature needs and huge carbon emissions make it environment unfriendly.

Before we curse the process, let’s understand how cement is produced these days?

Cement is produced in cement factories by taking materials from the earth, various carbonates, silicates and then processing it at very high temperature, greater than 900 or 1000 degrees Celsius depending on the type of cement and then processing it, grinding it, mixing it. So, it is an energy intensive process. And in addition to that it is environment unfriendly as this process emits a lot of carbon dioxide.

But we need cement for construction. Then what to do ? Here comes the saviour in the name of bio cement.

Bio-cement synthesis is more energy efficient as it requires temperatures in the range of 30 to 40°C whereas conventional cement production requires above 900⁰C.
Bio-cement is eco-friendly because it has negligible carbon dioxide emission, whereas conventional cement production is a significant contributor of global carbon dioxide emissions.
Bio-cement production can potentially be more economical since industrial wastes can also be used as raw materials for the bacteria.
Bio-cement production is faster in comparison.
Further, research on bio-cement has shown that it has comparable shear strength, durability and reduced water absorption capacity and permeability to the conventional cement.
The concept is decades old but it is yet to reach you. Why this is favourable, experts have the answer.
This process does not need high temperatures, it does not emit lot of carbon, it emits very little carbon dioxide and microorganisms are put out as part of their metabolism and so on. So, just by these mild conditions and no emission of carbon dioxide this material gets made. That is the basic difference.
Bacterias serves the purpose of making cement environment friendly. Not only this, it makes the cement self healing and the process is called Microbially Induced Calcite Precipitation (MICP). This is done in IIT Madras laboratories by the respective researchers. The IIT Madras Research team was led by Prof. G. K. Suraishkumar and Dr. Nirav Bhatt, Assistant Professor, both at Department of Biotechnology with Ms. Subasree Sridhar, Research Scholar, IIT Madras.
MICP is something like this. It is from the point of view of cementing things together. What happens is some bacteria under some conditions produce this calcium carbonate around them. They slowly generate calcium carbonate as a part of their metabolism. When they do this they bind various things together. Therefore, these bacteria under certain inert conditions, they get mixed with normal cement and then they are used when cracks appear in the cement. This is the biggest problem with cement when cracks appear in cement and leads to deterioration of properties, the air and water etc, get through those cracks, and reach these pores, that provides appropriate conditions for the germination of these spores to bring bacteria to the life form again. Once it becomes live, it produces calcium carbonate in the cracks, it cements the cracks and that way it becomes self healing. You just have to use this bacteria to seal the cracks.
A demonstration project of self healing roads was done in a village about 90 km from Bengaluru… The road was constructed in October 2015 was developed by an alumunus of IIT Delhi, Nemkumar Bhantia who is now a professor in the Civil Engineering Department at University of British Columbia in Canada.
This self healing road had to be monitored during the Indian summer and monsoon to make sure it lasted despite extreme weather fluctuations. After long observations, the road has been declared a success. It is expected to remain in best of its conditions for 15-20 years. No doubt, the concept of bio cement has the potential to radically change the construction industry. Then what are the we waiting for? Hope to adapt to such innovations and bring them to our life soon.