Turn to Crosby when essential projects must move forward despite cold weather
It’s a fact of life in the Midwest: When the temperature drops, the challenges associated with concrete pouring and curing rise. So when a project absolutely, positively must go forward despite cold weather and other adverse conditions, Crosby Construction, like many other contractors, adopts Cold Weather Concrete Placement Procedures.
“Although we’re a general contractor offering a full range of services, we specialize in the construction of new water- and wastewater-treatment facilities and in the modernization of aging water- and wastewater-treatment facilities throughout northern Indiana,” says Russ Jacobs, Crosby Construction’s senior project manager. “So, pouring concrete is a huge part of what we do.
“One of the biggest challenges we face every year is pouring concrete during the cold-weather months,” Jacobs continues. “We have to manage unpredictable weather conditions throughout the process, from pouring, to curing, to protecting the newly formed concrete from freezing. Of course, protecting our workforce from the extreme weather experienced while working outside in cold weather is also uppermost in our minds.
“In addition to the vast amount of experience in working with concrete in cold weather we’ve accrued over the years, we also adhere to the standards set forth by the American Concrete Institute, a nonprofit technical society,” Jacobs adds. “Solid experience, coupled with following proven formal guidelines, is a recipe for success.”
A brief look at the American Concrete Institute guidelines for the placement of cold-weather concrete, closely followed by Crosby Construction:
- Cold-weather procedures will be adopted when for more than three successive days the average daily outdoor temperature drops below 40°F.
- The average daily temperature is the average of the highest and lowest temperature during the period from midnight to midnight.
- Schedule and record pour dates.
- Monitor and record current and predicted temperatures.
- Do not pour on frozen sub-grade or surfaces.
- Do not pour when steel embedment or reinforcement steel surface temperature is 32° F.
- Do not pour when the ambient air temperature is predicted to be at or fall below 25°F.
- All structures, in-place forms, sub-grade, and older concrete surfaces shall be heated to 51° to 55° F +/- 2°F and protected prior to pouring new concrete. Monitor and record all temperatures.
- Confirm with the concrete supplier the temperature of the concrete when it leaves the plant.
- Confirm concrete temperature before the concrete is placed. Record results.
- Monitor concrete temperature during pours. Record results.
- Never pour concrete that has lost more than 15°F to 20°F of temperature.
- Once concrete is placed, measure the temperature of the surface at regular intervals and record the results.
- Protect freshly poured concrete from freezing and maintain surface temperature for a minimum of three days.
- Do not allow the surface temperature to drop below 40°F to 50°F in a 24-hour period. Install additional combustion heaters if required to maintain the minimum surface concrete temperature. Do not overheat.
- Protect all concrete from freezing for 24 hours during periods that are not defined as cold weather.
“As one can see from these general guidelines, and the ACI standards for Cold Weather Concreting (306.1-90), the proper placement of concrete is a science,” Jacobs says. “Having the necessary experience and following these guidelines is important regardless of the season. However, it’s even more important during the winter months.