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December 17, 2020
The building industry tends to work year-round, which means that concrete is poured and placed no matter the time of year. Although concrete can be placed in cold weather, certain precautions should be taken to ensure the job is handled properly. Take a look at the following six mistakes you want to avoid when placing concrete in cold weather.
MISTAKE #1: PLACING ON FROZEN GROUND
If the ground is frozen or covered with ice or snow, you should not place your concrete. Frozen ground will settle as it thaws, which leaves your concrete susceptible to cracking. In addition, when wet concrete is placed on a cold surface, the concrete will set more slowly. This, too, can create cracking in the concrete.
MISTAKE #2: ALLOWING CONCRETE TO FREEZE
Plastic concrete freezes at about 25° F and doing so can reduce its final strength by more than 50%. Therefore, it is important to keep fresh concrete from freezing until it reaches a compressive strength of at least 500psi.
It is very important to protect the concrete and keep it as warm as possible (at least 50° F). This can be accomplished with thermal blankets or through the use of heaters.
MISTAKE #3: IMPROPERLY USING HEATERS
In order to keep concrete at least 50° F, it’s a good idea to use heaters. However, if you use these heaters incorrectly, you could cause a large amount of damage. For instance, if you’re using a fuel-fired heater, be sure that it is properly ventilated. If not, the carbon dioxide given off in the exhaust can create a chemical reaction called carbonation, which can cause the surface of the concrete to become weak and dusty.
MISTAKE #4: USING COLD MATERIALS
Aside from ensuring that the concrete and ground are warm enough, it’s also important to ensure additional building materials are also warm. For instance, any forms, embedments, or tools being used during the concrete placing should be warmed up to at least 32° F.
MISTAKE #5: MISJUDGING DAYLIGHT
During the winter months, daylight seems to leave as quickly as it appears. If you are running behind schedule, you could end up losing out on the daylight you need to complete the job. Always be sure to try and schedule your concrete pours during the day. Not only does this give you an ample amount of light, but it also allows for a warmer temperature. If you will be forced to place concrete before the sun rises or after it sets, be sure you have plenty of lights and heaters on hand.
MISTAKE #6: SEALING WHEN IT’S TOO COLD
Most concrete contractors will either seal the concrete after it has cured or will recommend sealing to the customer. While sealing concrete offers plenty of benefits, it shouldn’t be done if the temperature is less than 50° F. If you are placing concrete in cold weather, be sure to follow the manufacturer’s recommendations before sealing.
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