December 15, 2000
Doctoral student develops cement
that cures below freezing
WEST LAFAYETTE, Ind. 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 Centers 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 minus 8 degrees Celsius, 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. "Currently, the U.S. construction industry spends about $1 billion dollars per year to provide heated enclosures for placing concrete at below-freezing outdoor temperatures. Approximately $800 million of that cost is in heat from non-renewable fossil fuels, much of which could be saved by adopting this new low-temperature concrete technology."
Korhonen has received the Hammer Award for leading the research team. The award is issued by the vice president of the United States and recognizes innovation in government research. The hammer is symbolic of "hammering away at building a better government."
Korhonen is chairing a committee of the Civil Engineering Research Foundation to expedite the technology's acceptance in the construction and engineering communities. The committee, which first met in October, has members from academia, research, construction, manufacturing, standards and government.
Current construction techniques for using concrete in cold weather have remained largely unchanged since the 1950s, said Menashi Cohen, a professor of civil engineering at Purdue and Korhonen's advisor.
The ingredients in concrete have to be heated to melt any ice, and the concrete must be kept warm until it gains sufficient strength. Korhonen's work shows that concrete can gain strength at below-freezing temperatures without the need for heat, he said.
As part of his doctoral thesis, Korhonen is investigating how durable low-temperature concrete mixtures are in terms of how well they stand up to the constant freezing and thawing of everyday use. This question is important because the freeze-thaw cycle is a major cause of damage in concrete structures.
A Purdue doctoral candidate, Korhonen has been a member of the Army laboratory's technical staff since 1975. He lives in Etna, N.H., and is writing his doctoral thesis in absentia, having passed his oral and written exams and satisfied all other degree requirements. He is a coinventor holding two patents and an author of more than 60 technical reports and journal articles pertaining to moisture problems in roofing systems, cold region building coatings, and improved cold weather concrete and masonry construction practices.
Source: Menashi Cohen, (765) 494-5018, firstname.lastname@example.org
Writer: Emil Venere, (765) 494-4709, email@example.com
Other source: Marie Darling at (603) 646-4292, Marie.C.Darling@erdc.usace.army.mil
NOTE TO JOURNALISTS: Korhonen can be reached through Marie Darling at (603) 646-4292, Marie.C.Darling@erdc.usace.army.mil
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