Concrete Construction During Winter
We often get questions about winter construction and more specifically whether or not concrete construction can occur in the winter months. Although not ideal, it is very normal for concrete construction to occur during the winter months.
We just broke ground on an addition for a commercial car dealership building and it’s already been snowing. Last winter we built a 36,000 sq. ft. commercial building in the dead of winter. As you can see in the photos we we’re right in the middle of pouring concrete footings for the building in the dead of winter.
Complications of Pouring Winter Concrete
Winter concrete construction is certainly more complicated for several reasons.
- Concrete achieves strength by a chemical process called hydration. The process happens when water combines with Portland cement. The process works best when the hydration water is warm. The cold weather in the winter slows down the chemical reaction and therefore slows down the rate of strength gain. Ultimately all that really means is you need to wait longer before you apply any significant structural loads to the concrete.
- In order to combat the low temperatures and slow rate of hydration, chemical accelerators can be used. In the past calcium was used to accelerate the chemical reaction and increase the strength gain of concrete. However, over the years we’ve discovered that calcium helps cause corrosion in the reinforcing steel. So today we use non-chloride accelerators in order to protect the reinforcing steel from corrosion.
- Concrete plants actually use warm water when mixing concrete in the winter. As you can imagine this can be quite costly due to the shear volume of water that must be heated.
- Finally insulated blankets and heaters are used to protect concrete from freezing when it’s first poured. This allows the chemical process of hydration to continue and therefore continue to create stronger concrete.
So the answer is yes you can continue concrete construction in the winter. It’s typically more expensive and slower going. However, there are times when winter concrete makes sense from a schedule point of view. Be sure to ask your concrete construction contractor whether they have experience doing winter concrete work. Make sure they are responsible for covering their work with frost blankets.