researchers develop self-healing concrete that can fill its own cracks in 24 hours

concrete, the most widely used man-made building material, is known to have a massive carbon footprint, contributing around 8% of global emissions. in order to tackle this problem, researchers at worcester polytechnic institute (WPI) have developed a self-healing concrete that is four times more durable than traditional concrete, extending the life of concrete-based structures and eliminating the needs for expensive repairs or replacements. the process uses an enzyme found in red blood cells that reacts to CO2 to create calcium carbonate crystals which can fill cracks before they cause structural problems within 24 hours.

‘the global use of concrete is ubiquitous,’ said nima rahbar, associate professor of civil and environmental engineering and lead author of the paper. ‘if tiny cracks could automatically be repaired when they first start, they won’t turn into bigger problems that need repair or replacement. it sounds sci-fi, but it’s a real solution to a significant problem in the construction industry.’

(main image) by simone hutsch on unsplash 
(other images) courtesy of worcester polythenic institute

inspired by the process of CO2 transfer in nature, rahbar’s research uses carbonic anhydrase (CA), an enzyme found in red blood cells that quickly transfers CO2 from the cells to the blood stream. the CA enzyme, which is added to the concrete powder before it is mixed and poured, acts as a catalyst that causes atmospheric CO2 to create calcium carbonate crystals, whose matrix is similar to that of concrete. when a small crack forms in the enzymatic concrete, the enzyme inside the concrete connects with CO2 in the air, triggering the growth of a new matrix that fills in the crack.

‘we looked to nature to find what triggers the fastest CO2 transfer, and that’s the CA enzyme,’ said rahbar, who has been working on self-healing concrete for five years. ‘since enzymes in our bodies react amazingly quickly, they can be used as an efficient mechanism to repair and strengthen concrete structures.’