Self-healing concrete could save costs and lives

Concrete is the most widely used construction material in the world but despite its durability, it is not immune to cracks and wear over time. Once cracks start to appear and expand, structural integrity of the building will be compromised and risk of collapse increases greatly.

Repairing the damage could be a costly exercise but more importantly, lives will be at risk.

Researchers from Netherland’s Delft Technical University have come up with what they hope to be the ultimate solution to this problem - concrete that can seal its own cracks.

Dutch microbiologist Dr Hendrik (Henk) Jonkers, who is leading the research, has spent the past few years developing a new type of concrete with self-healing properties he calls 'BioConcrete'.  Compared to regular concrete, BioConcrete involves one extra step in the mixing process – adding clay pellets containing bacillus spores and pellets with calcium lactate nutrients.

Both of these pellet sets will remain dormant in the concrete until cracks start to emerge, during which the elements will be let in. A reaction between the water and bacillus bacteria then forms limestone which closes up the cracks.

"You need bacteria that can survive the harsh environment of concrete. It’s a rock-like, stone-like material, very dry," Dr Jonkers told CNN.

"The next challenge was not only to have the bacteria active in concrete, but also to make them produce repair material for the concrete – and that is limestone."

This seemingly magical concrete is designed to last for 200 years and that is largely due to bacillus’ ability to lie dormant for decades, without the need for oxygen.

The technology can seal cracks up to any length provided they have a width of no more than 0.8mm.

Dr Jonkers was named a finalist in the European Inventor Award of 2015 in the Research category for his invention.

"Hendrik Jonker's bacterial concrete extends the life of bridges, streets and tunnels and opens up completely new perspectives for concrete production," says European Patent Office (EPO) President, Benoît Battistelli.

"This forward-looking innovation is a successful combination of microbiology and civil engineering - two sciences that are unlikely collaborators at first glance."

From the look of things, BioConcrete is set to revolutionise the construction industry and could potentially pay itself off by significantly lowering concrete maintenance and repair costs.

However, the cost of BioConcrete as it stands might hinder its entry into the commercial market, as a cubic-metre of the material will cost around €160 (approximately $A236) to produce, as opposed to €80 (approximately $A118) per cubic-metre for standard concrete.

Dr Jonkers is currently in discussions with several companies to examine BioConcrete’s commercialisation potential.