Purdue doctoral student Charles J. Korhonen has led a team developing a new type of cement that cures in below-freezing temperatures, an innovation with implications for the construction industry, which spends hundreds of millions of dollars annually to heat construction sites.

Korhonen is a research civil engineer with the U.S. Army Engineer Research and Development Center's Cold Regions Research and Engineering Laboratory in Hanover, N.H.

He has received a national award for leading the team that developed the cement to solve a problem at the Sequoyah Nuclear Power Plant, operated by the Tennessee Valley Authority and located near Chattanooga, Tenn.

The concrete floors in the plant's ice-storage rooms had heaved upward because of frost action and needed to be repaired. The dilemma was that the work had to be done under the tight time constraints of a nuclear refueling outage and at - 8°C, the operating temperature of the ice-storage rooms. The storage room temperature was too cold for ordinary concrete to cure properly. Shutdown of the rooms was not possible, since each day of shutting down the plant represented $1 million in lost revenue and service interruptions to utility customers.

Korhonen, in a joint effort with the Tennessee Valley Authority, S&ME Singleton Labs in Louisville, Tenn., and a private material and concrete construction consultant, developed a lightweight Portland cement mixture that allowed repairs without shutting down the nuclear plant or disrupting service.

“This technology for placing concrete at sub-freezing temperatures could extend the concrete construction season by several months in much of North America,” said Korhonen.