You don’t have to stop working on your exterior design projects during the winter, but the autumn and winter chill do raise an important question: do you know how to pour concrete in cold weather?
It can be done, but cold weather can have some adverse effects on concrete. If you prepare ahead of time, you’ll have a much easier experience pouring concrete in colder temperatures. Our guide will walk you through figuring out when it’s okay to pour, how to ensure your concrete won’t crack in the cold, and how to know when to leave it for another day.
Question One: Can You Pour Concrete in Cold Weather?
Yes! However, there are additional considerations to be made when it comes to pouring concrete in cold weather, so don’t assume that it’s safe to pour no matter what.
First of all, the American Concrete Institute defines “cold weather” for pouring concrete as a climate with a daily air temperature of less than 40 degrees Fahrenheit and not greater than 50 degrees Fahrenheit for half of a given 24-hour period. If it’s been colder than 40 degrees for three days in a row, you should follow the ACI’s guidelines for working with concrete in cold weather.
It’s also important to note that many concrete sealers should not be used if the temperature is below 50 degrees Fahrenheit. If you’re working with concrete in cold weather, be sure you keep in mind that it isn’t just the concrete to look out for, but also everything that goes into the process, including sealers and equipment.
Question Two: Can Concrete Cure in Cold Weather?
Yes, concrete can cure in cold weather. However, you shouldn’t add additional water to it. Too much water can cause problems if the concrete freezes, even if it reaches the desired compressive strength.
Concrete needs to be kept at 50 degrees Fahrenheit or above to properly cure. If the ground is frozen, the concrete closest to the ground will cure more slowly and potentially cause cracking as the ground thaws. To prevent this, avoid pouring onto frozen ground, and use portable heaters, blankets, or enclosed structures to keep the concrete above 50 degrees.
Question Three: Can Concrete Freeze?
Yes! Concrete freezes at about 24 degrees Fahrenheit, which can cause problems with the compressive strength. Typically, concrete takes around 24 hours to reach 500 psi, which is when it is believed to be stable enough to resist damage from freezing. Cold weather extends that time to reach 500 psi to around three days, increasing the window for something to go wrong.
If concrete freezes within that window, its strength can be reduced by up to 50 percent. It also becomes more susceptible to damage from weather and water, though it can be restored to almost normal strength if it’s cured and insulated properly.
Question Four: Can You Speed Up Concrete Drying in Cold Weather?
Yes! Concrete accelerators for cold weather can help speed up setting. Calcium chloride is one such accelerant, as it makes the hydration reaction go faster. However, chloride can corrode steel, so adding calcium chloride as an accelerant should not be done if rebar or similar materials will be used with the concrete.
There are other kinds of accelerators as well. They tend to be more expensive, but may work better for certain projects, such as those using colored concrete or concrete projects involving steel.
Adding additional concrete or using Type III concrete can also speed up the setting process.
Do you have more questions about how to pour concrete in cold weather? Ask us in the comments! And if you’re ready to get your backyard renovation project started—no matter what the temperature outside is—contact your local Transblue Franchise today!