CONCRETE THAT SEALS ITS OWN CRACKS DEVELOPED AT PNNL

Concrete is the world’s most common building material. We use three tons each year for every human on Earth, according to the journal Engineering Failure Analysis.
But it doesn’t last; patching cracked and broken concrete costs businesses and public agencies $12 billion annually in the U.S. alone, the journal says.
That yearly tab could drop dramatically now that the Pacific Northwest National Laboratory (PNNL) has invented concrete that patches its own cracks.
PNNL engineers mixed polymers – very large or long-chain molecules – with cement, the main ingredient in concrete, bonding the two materials. 
They found that when concrete made from the mixture cracks, the polymers draw the cement to the crack and bond across the fissure, sealing it within 24 hours of it appearing.
Even better, the polymerized cement responds to cracks before they become visible, reducing cracks seen by the unaided eye by about 90 percent.
Just as important, the polymerized cement increases concrete’s flexibility by 70 percent, giving it the ability to remain intact under the impact of collisions, hurricanes, and other stresses that normally fracture concrete.
According to PNNL, their concrete mixture can triple the lifetime of concrete structures and will be especially important in oil well bores, nuclear power plants, and other high-stress, high-temperature spots.
TRENDPOST: In 2019, about 230,000 bridges in the U.S. alone needed repair and 47,000 were downright unsafe, according to the American Road and Transportation Builders Association.
The number has only grown since then, yet politicians are unable to allot the money needed to fix them. 
PNNL’s new “elastic” concrete, coupled with sensors now being tested in concrete structures to alert engineers to impending failures, will allow builders to target scarce repair or rebuilding funds to the bridges, buildings, and other structures where they’re needed most urgently.