Concrete in Cold Weather
In our last post, we started talking about curing concrete in cold weather. Sometimes covering your work area in blankets simply won’t cut it when you’re pouring concrete in cold weather. If your job requires more insulation in order for the cold weather concrete to set, there are more options.
If regular blankets alone aren’t enough to insulate your concrete, you can use hydronic heating pipes. You can lay the pipes over the concrete that you’re curing, and the heat will help add to the warmth within the covered work area. Additionally, you can use electric heating blankets instead of normal blankets, which will increase the temperatures surrounding the setting concrete.
Sometimes you may be involved in a job that requires placing concrete where it’s too cold to even pour it outside. In circumstances such as these, you need to enclose your workspace and heat the air within the space. Setting up a temporary enclosure is an expensive operation, but sometimes it’s the only option if a job must be completed at such a time.
Carbonation becomes a problem when you’re working with concrete in an enclosure, or even in a building that’s using a temporary heat source. Unvented heaters and gas-powered equipment can increase the levels of carbon dioxide in the workspace, which can create a chalky, carbonated layer on the surface of concrete. The layer created by this reaction is soft and an unacceptable result for the job. For this reason, it’s important to use heathers that can exhaust to the outside of your enclosed workspace. Always be sure to have someone monitoring the heater overnight, so that it remains fueled and functioning.
Another problem that occurs when curing concrete within an enclosure is that dry, hot air may sometimes cause the concrete to cure too quickly, which dries the concrete out and crusting may occur. If you’re using propane-powered heaters, you also run the risk of fire, which is something to be aware of at all times.
If the concrete stays at about 50°F, you can remove the protection you’ve put in place after two days. It’s best to wait about 4 weeks before using the area where the new concrete has been placed.