‘BioConcrete’ – The Remarkable ‘Self-healing’ Concrete

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What is, your apartment fixes itself while you catch up on some of your favorite seasons this summer? Or better still, spend your house ‘maintenance and repair’ money on a nice little vacation in Hawaii while you let your house repair itself? This is no sci-fi concept. Say hello to ‘bio-concrete’, the concrete that heals itself!

The green revolution is upon us. Whether it is global warming that has triggered this phenomenon or it is the awakening and awareness of mankind, people have started incorporating natural substances in everyday inventions, technology and the environment around them. Almost every other industry has opted for this path and the construction industry is no exception.

The construction industry has been growing rapidly ever since modern methods of construction were developed along with the creation of modern construction machinery. Concrete is at the heart of all of this growth. Although concrete is not a new invention and Romans have been using it in the construction of their buildings some 2000 years ago. With growing world population and boost in the economy, construction hasn’t seen a downward trend in present times. China and India alone are the biggest users of concrete. In fact, China has used more concrete in the last 3 years than the United States has in the last century!

Although it is a staple construction material, concrete has its problems. No matter how and where concrete is made, it always ends up with cracks. Because the material is extremely hard and dry, it is prone to developing cracks over time. These cracks, if not fixed in time, lead to leakage in our walls and ceilings and can lead to water reaching the steel reinforcements used in concrete. Water will eventually cause corrosion of the steel bars and cause the structure to collapse.

Apart from this, fixing concrete is very expensive. Even though it has its drawbacks, it is highly unlikely that concrete will be replaced by any other construction material in the near future. It builds our buildings, paves our roads and spans our bridges and is the most widely produced and consumed material on earth apart from water, according to a WBCSD report.

Hendrik Jonkers, a microbiologist at the Delft University of Technology in Netherlands, has come up with a remarkable invention that has the potential to increase the lifespan of concrete and which will rid us of all of our building repair woes.

Bio-concrete, as he calls it, is normal concrete with special bacteria mixed in it. These bacteria are actually limestone-producing bacteria and when mixed with concrete, they can make the concrete to ‘heal itself’ where cracks form. It is an incredible invention.

The mechanism involves the bacteria Bacillus pseudofirmus or Sporosarcina pasteurii. These bacteria thrive in alkaline environments and are found in lakes near volcanoes. When they come in contact with water and feed on calcium lactate, they produce limestone. This limestone fills up the crack in the concrete.

In order to let these bacteria work only when required, they are enclosed in biodegradable capsules along with the calcium lactate. When the concrete forms a crack and comes in contact with water, it will activate the bacteria to do its job. Since these bacteria can live for up to 200 years without water or oxygen, they can keep on doing their job for a very long time.

The only problem with the use of bio-concrete is its high price. It is almost double the price of normal concrete. The reason is the use of calcium lactate as food for the bacteria. Although a sugar source was also tested to serve as food for bacteria, but it made the concrete weak. Unless it is available at a lower, more affordable price, its use cannot be widespread and benefits will not reach the common man.

Other than affordability, this self-healing concrete can’t cure very wide cracks or potholes on roads just yet; the technology is currently able to mend cracks up to 0.8mm wide. More research and testing required to make it a viable alternative green construction material is well underway.

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