Can you really pour concrete in the winter?

Burning question, Can you pour my foundation and garage floor in the winter? YES! ABSOLUTELY. 

Concrete sets very slowly below 50°F and below 40°F the hydration reaction essentially stops and the concrete will not gain strength. But, remember, these are CONCRETE TEMPATURES. NOT AIR TEMPERATURES. when it's cold outside, we need to protect the concrete until it can handle the cold on its own. The general rule of thumb is that once the concrete has gained strength of around 500 psi then it is fine to continue curing on its own.

One thing that happens at almost the same time the concrete has achieved 500 psi compressive strength, is that the hydration of the cement has consumed almost all of the water in the original mix. 
so even if it did freeze, there wouldn't be enough water left in the pores to damage the concrete. With most concrete projects, even at 50° this usually happens during the second day after it has been poured. Winter-poured concrete actually has a better compressive strength than concrete poured in the summer because of the slow curing process that the exterior temperature allows. It also finishes much nicer due to the increased working time we have!

To help it reach that 500 psi strength, there are two things we can do in extreme cold weather, and don't forget concrete is an exothermic reaction, So it creates some of its own heat!


1. Change the mix to allow it to set more quickly. 

2. Protect the concrete from the cold—or more than likely both of these. And we do both!

We can change the mixture from the batch plant by adding hot water instead of cold. And Bringing the temperature to around 65 degrees when the mix leaves the plant. We can also add accelerators such as calcium chloride or extra cement which will hydrate more rapidly. We use ground heaters and "blankets" during winter construction. which allows us to un-thaw the ground, warm it up, and dry it out. The blankets keep your foundation concrete warm until it is cured in conjunction with the heaters. All of this allows us to work year-round building dreams.