in an ideal world, all outside concrete work projects could wait until the warmer months. But sometimes the construction schedule doesn't match up with Mother Nature and you have to start laying concrete when the temperatures are dipping well below freezing. There are a few tips and tricks you need to keep in mind before beginning the project to ensure that the concrete comes out stable, smooth and suitable for your project.
Use the Right Concrete Mix
Your concrete mix should include instructions for using hot water during the mixing process for a cold weather project. Make sure you follow the directions closely and ensure that both the water and the resulting concrete mix are at the specified temperatures. This process makes sure that the interior of the concrete doesn't freeze and weaken during the setting process.
Ask your concrete supplier to provide an accelerator that can also be mixed into the concrete so that it sets up faster in the cold weather. Note that if you plan to implant any steel beams or posts in the concrete, you want to make sure that the accelerator doesn't contain calcium chloride. This cheap material works well as an accelerator but will eventually eat through and weaken the steel.
Keep the Setting Concrete Warm
You need to keep the concrete warm during the setting process to prevent freezing and allow the mix to actually set up properly. Invest in some concrete warming blankets that cover the entire surface of the concrete to keep the mix warm enough to do its job. Resources like Powerblanket would have the necessary equipment.
Make sure that you put extra layers of blankets around the exterior of the concrete where it meets with the ground. This prevents the contraction and expansions of the ground from perverting the integrity of the concrete in those areas. You also want to wrap up any posts or beams sticking out of the concrete to prevent the same problem.
The warming blankets might need to be kept on the concrete for several days depending on the temperature of the air and surrounding ground. Keep checking the concrete underneath to see how the setting is progressing. You can also use a thermometer to ensure that the concrete is staying warm enough under the blankets.
Use a Wet Vacuum to Remove Bleed Water
Bleed water is essentially some of the concrete mix water that gets pushed to the surface when the concrete sets. The bleeding process tends to happen slower in colder temperatures but it makes it more important for you to remove the water as it appears so it doesn't freeze. A wet/dry vacuum is often enough power to remove the bleed water as it appears. Work quickly but carefully so that you can return the concrete back under the protection of the blankets to finish setting.Share
20 February 2015
When I was in college, I lived in an old house just south of the university campus with five other girls. When we came back from Christmas break, the heater was broken. The beginning of January was the coldest time of the year, and because it was the weekend, the heating company couldn't come fix it for a few days. My roommates and I pulled our mattresses into the front room and slept all together to keep warm. Two weeks later, our heater broke again! That time we ended up getting a completely new furnace. Needless to say, we got to be good friends with the heating contractor that month, and it was a good experience that led to the creation of this blog.