While you might be presented with several challenges when pouring ready mix concrete, the additional procedures and extra effort taken normally pay off in the long run. In situations where weather is extremely cold, concrete must be continuously protected from getting too cold as this would result in its weakening, something that significantly increases the risk of breaking and cracking. But by taking certain preventative measures, you can comfortably pour concrete in extreme weather conditions.
For concrete to set properly and harden, a chemical reaction best referred to as hydration must take place. This consists of the chemicals in the concrete reacting with water to bind together the mixture. For hydration to occur, the temperature of the concrete must be 40ᵒF. Anything below this temperature range has the effect of slowing down the hydration process. Sometimes, it has the effect of making the process to stop. In extreme weather conditions, proper care must be taken to make certain ice crystals do not form during the curing process. Excess water amounts in the concrete mixture have a direct connection with the resultant damaging effects.
Heat is required during the hydration process. There are a number of ways to increase the temperatures during the hydration duration. If you are using the normal concrete mixture as we know it, simply add additional cement to the mix. The extra cement with provide extra heat to the hydration process. If you are ready mix concrete, then simply use any of the available heating component.
While it is typically difficult to thoroughly heat the aggregates in the mix, it can still be done if you know what you are doing. You can also heat the mixing water to ensure equal predictability and performance. To make sure the heated mixture is adequate for utilization, it is best stored underground or indoors.
Add a chemical accelerator to the mix
Besides heating the concrete mixture, a chemical accelerator can also be added to the mix to speed up the hydration process. By speeding up the hydration process, the setting time of the cement is speeded up. The two commonly used accelerators are non-chloride types and calcium chloride varieties. Calcium chloride accelerators, however, can cause corrosion to any steel used in the concrete. The non-chloride varieties, however, are not corrosive and hence can be utilized in much larger quantities. The only drawback with non-chloride accelerators is that they are pricier than their calcium chloride counterparts.
How cold is too cold?
Cold weather is considered temperatures below 40ᵒF, for five consecutive days. These temperatures must not be above 50ᵒF for more than one day. To prepare your site for concrete pouring, make certain to have all of the proper heating and insulation equipment on your worksite and ready to go. Remember, the colder the surrounding air temperature, the more difficult it is to maintain a stable concrete temperature. The temperature of the sub-grade must be as close to the temperature of concrete being poured as possible. Once the concrete is poured, a liquid curing compound must be sprayed over the concrete and protected with an insulated blanket. If the slab being worked on is in an enclosed area, make sure to use a ventilated heater to maintain optimal hydration temperatures.