Recent natural disasters such as hurricanes in the Caribbean and earthquakes in Mexico have laid bare the need for more resilient buildings. Fortunately, researchers at the University of British Columbia (UBC) have developed a sprayable, eco-friendly concrete that makes the exterior of buildings as strong as steel and able to withstand unforeseen disasters. The material is called Eco-friendly Ductile Cementitious Composite, or EDCC – and it’s is predominantly comprised of an industrial by-product called fly ash.
Said UBC Professor Nemy Banthia, “The cement industry produces close to seven percent of global greenhouse gas emissions. By replacing nearly 70 percent of cement with fly ash, we can reduce the amount of cement used. This is quite an urgent requirement, as one tonne of cement production releases almost a tonne of carbon dioxide into the atmosphere.”
The final product is very similar to steel. It is durable, malleable and much more ductile than ordinary concrete. To test the invention, researchers sprayed EDCC on concrete block walls about 10 mm (one-half inch) thick. They then simulated a magnitude 9 earthquake — the same strength of the earthquake that rocked Tohoku, Japan, in 2011. “The results of these tests have been amazing,” said UBC engineering Ph.D. candidate Salman Soleimani-Dashtaki. “We can shake the wall extensively without it failing.”
The video above shows that the unreinforced wall collapsed at about 65 percent intensity. In contrast, the reinforced wall withstood full intensity shaking and flexing. “A 10 millimeter-thick layer of EDCC … is sufficient to reinforce most interior walls against seismic shocks,” said Soleimani-Dashtaki.
EDCC is already on the market – in British Columbia, Canada, the product has been designated as “an official retrofit option.” The product is growing in popularity, as it is more cost-effective than major structural renovations or the steel bracings often required for earthquake protection.
Plans are already in motion to reinforce the walls of an elementary school in Vancouver, B.C., and to upgrade a school in the seismically active area of northern India. With this technology, the costs of retrofitting buildings is cut in half. Said Banthia, “This can be very easily scaled to other projects. It costs about half of what other retrofit strategies would cost.”