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Cold Weather Concrete Innovators

Walsh Construction, known as experts in heavy civil construction, received a contract from the U.S. Army Corps of Engineers to repair a portion of the Illinois Waterway, which connects Lake Michigan to the Mississippi River. The project, located in the Lockport Lock and Dam area, focused on repairing two-and-one-half miles of concrete wall with a panel construction.
The timeframe of the project dictated that concrete pours needed to continue during the Illinois winter. Since water in concrete can freeze starting at 30⁰F/-1⁰C, and at about 27⁰F/-3⁰C the hydration process can stop entirely, cold temperatures posed a risk. Since ice occupies about 9 percent more space than water, the integrity of the concrete needed protection.
Walsh concluded that a system that could maintain temperature control, did not use an open flame, and would retain moisture in the concrete would save them fuel and labor costs.
Walsh Construction, in evaluating its cold weather concreting options, determined that maintaining an open flame oil-heater to cure the concrete would cost several thousand dollars a month in on-site personnel. Further, that cost would not include the labor to build and move enclosures on the 40 foot (12.1m) long segments, or the cost of the fuel for the open flame heater.
After talking to Blue Sky Contractors Supply in Merrillville, Indiana, Walsh found an alternative that saved time and money. The company purchased eight Powerblanket® 6’ x 25’ (1.8m x 7.6m) and eight 3’ x 25’ (0.9m x 7.6m) Multi-Duty heating blankets.
After calculating the savings in fuel, personnel to monitor the open flame, personnel and time to build and move enclosed shelters, and the heaters themselves, Walsh Construction realized it saved more than $5.43 for every $1.00 spent on the Powerblanket® blankets.
Even better, the workers on the site found the blankets much easier to work with. In fact, Vern Adkins, Carpenter Foreman with Walsh Construction, stated that this was the best cold-weather heating /curing system he’s worked with.
Because of the GreenHeat® Technology used by Powerblanket® products, the heat spreads evenly, and even the corners and edges of the concrete receive protection. The thermal im-age records how evenly the product spreads heat. In fact, 98 percent of the temperature data points measured within a range of 137°F to 147°F – only 10 degree difference (58.3⁰C to 63.8⁰C).

Test Results

■ 2.8 Times Faster—that’s how much a recent test found that Powerblanket® cur-ing blankets outperformed standard curing blankets. That means doing jobs quicker in the winter.

■ 3,925 psi (276 kgf/cm2)—the strength of the concrete cured under the Powerblan-ket® curing blanket during the three-day test, which took place in temperatures ranging from 22⁰F/-5⁰C to 38⁰F/3.6⁰C.

■ 2,162 psi (152 kgf/cm2)—the strength of the concrete cured under a standard cur-ing blanket in the same test.

■ To read the test , visit powerblan-ket.com/concrete.