NIST Touts Performance of Internally Cured Concrete
The federal agency joined Purdue University researchers to champion this technology, which can extend the service life of bridge decks and thus reduce state repair and maintenance costs.
The National Institute of Standards and Technology, a Commerce Department agency, reports Indiana state transportation officials are making use of "internally cured" high-performance concrete. Research by Purdue University and NIST researchers showed its use can extend the service life of bridge decks and reduce the state's repair and maintenance costs.
A NIST release quotes agency engineer Dale Bentz, who said water is an essential part of the chemical reaction that gives concrete its strength. "The chemical reaction is ongoing for years and years," he said. "It essentially never stops, but it keeps going slower and slower. Usually, about 75 percent of the reaction has occurred by 28 days, but the other 25 percent might happen over many, many years, as long as there is still water available and those reactions can still take place."
Bentz worked with Purdue's Jason Weiss on internal curing, a technique for distributing extra water uniformly throughout the concrete in absorbent materials mixed in with the cement and aggregate. The resulting concrete is more resistant to early-age cracking, which is especially important for concrete bridge decks. Cracking allows winter deicing salts to penetrate more rapidly and damage steel rebar, Bentz said.
Making concrete in this way also allows for more environmentally friendly concrete mixtures, he said.