Icy cold weather doesn’t have to hold building pros back from working with concrete. Although concrete sets more slowly when the air temperature is colder, it can still be quite workable if you follow the right steps.
What helps concrete set in winter is water, which prohibits freezing. As the temperatures outside fall, workers at my company, Consolidated Concrete, heat up the water used in the concrete mix and use accelerators to help it set. The best news is once concrete is set, it cannot freeze.
Temperature does play a large role in the usability and strength of concrete and special techniques are needed when temperatures dip below 40 degrees F. First off, it’s important to find the right mix of concrete for cold temperatures through early spring. Fortunately, temperature issues can be overcome by adjusting the mix to match the prevailing conditions.
In addition, we ensure that everything that comes into contact with our customer’s mix is heated so the concrete leaves our plant at 65 degrees F, keeping in mind that the temperature will drop 25 percent during a one-hour delivery time. Our large heated water tank ensures that we can provide customers with as much warm concrete as they need.
Another important factor in working with concrete during the colder weather months is the quality of the concrete mix itself. The right “recipe” is needed in order to ensure concrete will perform properly. This includes using setting accelerators and water-reducing additives, avoiding fly ash or slag cement as they set more slowly and generate less internal heat, and adding extra cement to the mix to generate its own additional heat.
Accelerators can help prevent frost damage by speeding the setting time so the curing can happen faster. By reducing the amount of water, the cement paste will have higher density, thus adding to the strength and weather-resistant qualities. We can also add accelerants to the mix which helps speed up the start of finishing operations which is important in cold weather.
Reducing or avoiding fly ash in the mix can also help reduce surface scaling, or peeling, when exposed to de-icing chemicals once the concrete is cured.
Lastly, it’s crucial
to prepare the curing site using the following tips as a guide:
•Never place concrete on frozen ground, ice, or snow
•Thaw the ground for a couple of days using heat pipes and blankets or electric blankets.
•Triple-wrap corners and protrusions.
•Remove standing water; bleed water needs to evaporate or be removed by a squeegee or vacuum.
•Keep setting concrete covered until it is cured – consider a temporary enclosure.
With a little advance planning and a skilled concrete contractor, you can ensure that your projects this winter and early spring will be successful and last for decades to come.