With proper planning, successful cold-weather concrete placement can be done. Cold weather conditions require special precautions when placing, finishing, curing and protecting concrete from the adverse impacts of low temperatures. In this blog, TR Concrete Construction Project Manager Nick Blanchard highlights the essential steps to take for winter projects in the Midwest.
Cold Weather Concrete Placement
The American Concrete Institute (ACI) definition of cold-weather concreting as stated in ACI 306 is, “a period when for more than three successive days the average daily air temperature drops below 40 degrees and stays below 50 degrees for more than one-half of any 24-hour period.”
Important steps to take for successful cold-weather concrete placement
All concrete must be protected from freezing until it has reached a minimum strength of 500 psi, which typically happens within the first 24 hours. Early freezing can result in a reduction of up to 50 percent of the design strength.
Prevent freezing temperatures.
Maintain subgrade temperatures above freezing. This can be achieved by covering with insulation blankets and/or use of ground heaters. Do not place fresh concrete on frozen ground.
Use hot water in the concrete mix.
Typically, concrete at placement should be 65°F or higher during cold weather months. Hot water use in the concrete mix helps offset the effects of cold weather. Adding hot water allows initial concrete temperatures and moisture levels to be maintained and can help concrete achieve normal cure times and strength gain.
Accelerating admixtures may also be used.
Since colder weather leads to colder concrete, the set time can be delayed. Accelerators added to the concrete can keep it on schedule. Accelerators also help prevent frost damage and allow finishing operations to take place in a timely manner.
Protect concrete after placement.
This can be achieved by covering with Insulation blankets and/or the use of heated enclosures.
Maintain proper temperatures during extended cure times.
The concrete must maintain a temperature above 50° for approximately 3 days for the concrete to reach the required strength. Continued use of concrete blankets keeps curing concrete warm and at ideal temperatures as it cures. Concrete should remain covered until cured.
Following these recommended steps when placing concrete in cold weather will help to ensure the concrete obtains the required design strength and mitigate other potential issues from concrete exposed to freezing.
TR Concrete Construction in Omaha, NE
This industry takes a lot of heavy machinery and tough labor, but it also requires as much or more planning, critical thinking, and fine touch to get a quality finished product. It is a very rewarding career and keeps you constantly on your toes being that 2 days are never the same. It is a profession that has been around for a long time and is ever-evolving and still remains a very vital staple in today’s economy.
As a reputable business with over 25 years of concrete construction experience, TR Construction has expertise with projects large and small to include:
- commercial building concrete
- remove, and replacement of concrete
- industrial projects
- special projects for clients