Back in 2009, the American Society of Civil Engineers gave U.S. infrastructure a grade 'D’, and said getting to 'B’ standard would require $2.2 trillion worth of investment. So, any technology that might make repairing bridges, roads, and buildings easier, and perhaps cheaper, is welcome.
Led by Chan-Moon Chung, a professor of chemistry at Yonsei University, in South Korea, researchers have come up with a protective coating for concrete that seals up cracks when exposed to sunlight. The research is written up in the journal ACS Applied Material Interfaces.
Though concrete is very strong and adaptable, it is also brittle. Fine cracks can easily appear that, when exposed to air and water, expand over time. The coating contains polymer microcapsules that melt over the gaps when exposed to the sun. And Chung says the agent is relatively inexpensive, and won’t freeze in winter.
Reached via email, he says the material should be available commercially within two years, but "the stability of the system needs to be investigated first."
There are several other innovative concrete ideas out there. A team from the Delft University of Technology, in the Netherlands, has developed a living "bio-concrete." The mixture is impregnated with a bacteria that produces a crack-filling mineral, called calcite.
The healing process is similar to the way human skin repairs itself: A paper cut heals much faster than an inch-wide gash. When Li’s concrete develops hairline cracks, the dry composite is exposed to the moisture in the air, which it absorbs. As it does, it "grows" new concrete, filling in the minuscule cracks. Meanwhile, calcium ions inside the cracked concrete mix with moisture and carbon dioxide from the air, creating a calcium carbonate material similar to what seashells are made of. This enables the concrete to regain its initial degree of strength.
Then there’s this biological concrete from Barcelona that supports fungi, moss, lichen, and allows you to create nice-looking living walls.
All in all, we’re in for a few new concrete ideas going forward, though all them will have to justify themselves in cost terms. They may heal (and beautify) themselves in the long term, but someone, as ever, will have to pay up-front.