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.