While only a short-term solution, mixing concrete while hot gives laborers and finishers the additional time required to finish a pour with measured precision. Water heaters are especially proficient when used in conjunction with space heaters. Without space heaters, electric blankets can end-up amounting to too-little, too-late.
Space heaters can be used to heat the ground prior to a pour and keep the temperature of concrete reasonably high while it is being poured and finished, until the concrete is ready to be covered. Blankets, of the three options, are the most critical. Except in the most extreme conditions, concrete will generally not freeze while being poured because the cement hydration process usually generates enough heat to keep the concrete above freezing until it is finished.
Once it is finished, if the concrete is not covered and the ground and air temperature remain below freezing, there is a good chance that some — sometimes all — of the concrete will freeze. Covering uncured concrete with electric blankets will prevent this from happening.
In conclusion, there are three things to remember about pouring concrete in the winter: temperatures above 50 degrees, but as close to it as possible is good for compressive strength; the freezing of uncured concrete is the worse possible scenario; and if you can only choose one means of keeping uncured concrete warm, choose electric blankets.
Ready to get started on that next project? Contact our team at BN Products for all of your concrete pouring needs or questions! Toggle navigation. The colder the temperature of concrete, the slower the speed of the reaction. In winter, your enemy is the clock. The concrete needs to harden as rapidly as possible to resist the pressures caused by water freezing within the concrete. If newly placed concrete freezes, the damage caused is immediate and permanent.
Even if you warm the concrete, and allow it to cure, the damage is done. According to the Portland Cement Association , if concrete freezes while it is still fresh, or before it has developed sufficient strength to resist the expansive forces associated with the freezing water, the concrete loses up to 50 percent of its compressive strength.
However, proper precautions help you successfully pour concrete during hot or cold weather. Maintaining the correct temperatures for the concrete curing process is extremely important. Concrete must set before it is exposed to freezing temperatures. You can overcome cold weather challenges by following the tips below:.
Offset detrimental effects from heat, humidity and wind with the following tips:. Pouring concrete in hot or cold weather is possible when you take the right steps and work quickly.
Keep in mind, set times will vary depending on temperature, no matter the time of year. With careful planning, you can achieve good results in less-than-ideal temperatures. For high-early strength concrete that won't be exposed to freeze-thaw cycles, one day at temperatures above 40 degrees is sufficient. But a concrete foundation or other structure that will carry high loads at an early age requires 20 days or more at a minimum temperature of 50 degrees. Remember that cement curing is an exothermic reaction that produces some heat on its own, and often it is sufficient to cover the concrete with polyethylene sheeting or insulating blankets to trap the heat.
Under no circumstances should concrete be allowed to freeze within the first 24 hours after pouring and placing. Finally, there are techniques you can use during the curing process to ensure the concrete reaches maximum strength:. Peter C. CRC Press, American Concrete Institute. Alireza Farzampour. Accessed Sept. Sina Kazemian, Bujang B.
Huat, and Maassoumeh Barghchi.
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