Concrete has been around since at least 6500 BC when Nabataea traders or Bedouins who occupied the regions of Southern Syria and Northern Jordan. Though it wouldn’t be until nearly 700 BC before they took advantage of hydraulic lime with self-cementing properties. With these tools at hand, this small empire constructed kilns to supply mortar for the construction of rubble-wall houses, floors and most importantly underground waterproof cisterns. The people of Nabataea were capable of thriving in the harsh desert partly due to the secret nature of the cisterns; some of which survive even today.
The Nabataea provide us with an important lesson however, by using the tools of the land they constructed creative solutions to face the problems their society faced. These solutions in turn benefited their empire but also the surrounding cultures. Fast forward to the Classical Era and we can see the strong advancements the Roman, Greece and Egyptian Empires cultivated and the massive landmarks we can still see today as an example of their wisdom.
It can feel at times as if time stands still, but even such discoveries as concrete made thousands of years ago continue to evolve and change today as new modern processes are discovered and cross developed into other fields. Two of the most interesting discoveries as of late have undoubtedly been Self Healing Concrete and Thirsty Concrete. Two radically different ideas that are shaping our future.
Self Healing Concrete
When we think self healing you wouldn’t be wrong to thing of biological material like skin on an animal. But in many ways that’s exactly how Self Healing concrete works. Professor Henk Jonkers, of Delft University of Technology in the Netherlands explains. “We have invented bioconcrete — that’s concrete that heals itself using bacteria,” Jonkers says. The biggest problem facing concrete are from stress or environmental conditions that create cracks, from these cracks water will seep into the concrete and cause damage to the structure. This also puts an environmental risk attached to concrete, forcing repairs or replacement to otherwise alright concrete structures. By creating self healing concrete, this negates the need for repairs and reduces the amount of environmental damage that can come from producing concrete.
As Jonkers explains, the bacteria that is added to the concrete mixture remain dormant until the concrete cracks and water gets in. This awakens the bacteria and allows them to create the repair material limestone. But bacteria still require a food source for the energy needed to repair the crack. As Jonkers goes on to explain, the concrete also contains calcium lactate in small capsules which are degraded as they come into contact with water, which allows the bacteria to germinate.
Here have a novel idea that takes the idea of water and concrete and flips it completely around. While previously we discussed the dangers of concrete and water in buildings or structures. Here we’re talking about road concrete, the type you drive your car or drunk on everyday. As anyone who has driven long enough knows, wet conditions on the road can often make driving incredibly dangerous to yourself and other drives.
This is where a company named Tarmac has come in. They have developed a new kind of concrete that is capable of absorbing up to 4,000 liters (1057 gallons) of water in the first minute. Then, as the concrete takes on more water, it typically slows to about 600 liters (159 gallons) per minute. Tarmac goes on to explain “The high-tech concrete works by having a permeable layer on top, which allows water to drain through a matrix of large pebbles and then down into a loose base of rubble beneath.”
All of this water eventually is fed into a drainage system that returns the water back into the city’s irrigation system. You check out a video of the water in action below, it’s pretty amazing!