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Building a Smart City from scratch – IX


Bio-concrete with self-healing properties. To the left is visible a portion of concrete with a crack. To the right the crack has been (slef) repaired by bacteria producing limestone. Image credit: Syn.de.Bio

9. Self-healing concrete

If you place a bunch of stones one over the other it won’t take long to discover that the structure is weak and will collapse at a moment notice. This is no news, our ancestors were familiar with the problem and as far as 8,500 years ago they had found a solution: using a sort of glue to provide strength. This is what concrete is. In these millennia the concrete has become better and better, resisting to water, becoming more elastic, when needed, able to dry even under water… The concrete we use today is an evolution of the Portland cement (1824, from the name of the city where it was invented, Portland in UK, not US!).

Today’s construction are making larger use of steel but concrete remains a crucial material in cities. Even the best quality concrete (and even prepared and deployed in the right way) over time is subject to wear. Stresses create cracks and these cracks let humidity and water seep in. Freezing makes it worse slowly making it brittle and the water seeping in may reach the iron rods providing structural strength rusting them.

This is why we often see repairs in tunnels and bridges and why from time to time buildings require maintenance.

Well, researchers have invented a way to shift the maintenance chore from humans to bacteria! A Dutch bioTech company, Green Basilisk (and it is not alone), has started to sell bio-concrete (see the video clip explaining how it works, produced by TU Delft).

The concrete is mixed, at the time of deployment, with bacteria that remain in a dormant state. Once the concrete cracks, the water seeps in and wakes up the bacteria that will start producing limestone. This acts like a sealant in the crack stopping the water and putting the bacteria back to sleep.

According to researchers bacteria will remain effective (they can be waken up) for 200 years, meaning that they can keep repairing the concrete over this span of time.

No wonder than, that BleuTech mentioned bio-concrete among the technologies they will be using to build BleuTech Park.

This is another example of smart material, one of many that will become in widespread use in the next decade.

About Roberto Saracco

Roberto Saracco fell in love with technology and its implications long time ago. His background is in math and computer science. Until April 2017 he led the EIT Digital Italian Node and then was head of the Industrial Doctoral School of EIT Digital up to September 2018. Previously, up to December 2011 he was the Director of the Telecom Italia Future Centre in Venice, looking at the interplay of technology evolution, economics and society. At the turn of the century he led a World Bank-Infodev project to stimulate entrepreneurship in Latin America. He is a senior member of IEEE where he leads the Industry Advisory Board within the Future Directions Committee and co-chairs the Digital Reality Initiative. He teaches a Master course on Technology Forecasting and Market impact at the University of Trento. He has published over 100 papers in journals and magazines and 14 books.