New Process Created For Self-Healing Concrete

The world of concrete coatings and repairs could be revolutionised in the near future thanks to a team of researchers working out of the University of Waikato in New Zealand, who have come up with a new way of allowing certain materials to heal themselves.

Led by Dr Aydin Berenjian and PhD student Mostafa Seifan, the scientists used a process known as solid-state fermentation and applied it with the help of nanobiotechnology to facilitate concrete regenerate and repair any cracks as they appear and develop.

While concrete is certainly one of the most versatile and widely used construction materials in the world, with billions of it used globally every year, it is still vulnerable to damage and any cracks can increase its degradation, drive up maintenance costs and even result in structural failure… until now, it seems!

A form of bio-concrete has now been created by the Waikato team, bringing in micro-organisms and nutrients into the usual mix of concrete so that calcium carbonate is created when cracking does take place. But the performance relies on numerous factors in order to be effective, including the availability of oxygen and the right nutrient ingredients and bacterial species.

Testing has thus far shown that the bio-concrete is more long-lasting and durable than traditional concrete – but cost is an issue at the moment, since the new product is more expensive than what is already out there on the market.

But it is worth noting that the new process is environmentally friendly and, because it is more durable, it’s more likely to be safe in places prone to earthquakes, for example. The team is now eager to see testing take place on a bigger scale, with Dr Berenjian excited for future applications of this bio-concrete.

He said: “With the help of the unique fermentation system and nanobiotechnology, we have engineered a process that makes the calcium carbonate production very efficient even in a harsh environment like concrete … Fixing concrete manually also means cracks are sometimes missed, particularly if they are not visible. The return comes with the longer-term strength and removing the cost of repairs.

“We have had a lot of interest and our work has been thoroughly reviewed and published. It has huge potential for a range of other materials, industries and uses worldwide.”

This is not the first time that self-healing concrete has hit the headlines, however. Back in 2015, the University of Cardiff led a project (known as Materials for Life) that trialled self-healing concrete at a site in the South Wales Valleys.

The overall aim of the project was to come up with a single system that could be embedded into concrete when it initially sets. This system will then sense automatically when damage occurs and is then able to repair itself independently, without any need for human intervention.

Shape-shifting materials known as shape-memory polymers was one technique used to repair big cracks in concrete.