Concrete Construction in Ottawa’s Winter

by TRP Ready Mix on December 8, 2017

 How to use ready mix concrete in Ottawa during the colder months.

How Concrete Construction Projects Continue, Even in the Winter Months

With Ottawa’s winter here in full force, the weather is becoming less ideal for concrete construction. Cold winters pose a threat to the quality of concrete because concrete will set slowly in colder temperatures, plus there is an added risk of freezing. If this happens, the concrete matrix will break up, resulting in a weak concrete that is prone to cracking.

But there are concrete construction projects that continue into the winter months. So how do they do it? Concrete experts in Ottawa know the trick to keeping concrete strong, even in cold weather. With a special winter mix, your concrete can set fast without freezing, maintaining its strength and quality.

Here’s how concrete suppliers mix concrete for use in winter.

Hot Water

To keep the concrete warm for longer in cold temperatures, concrete suppliers will mix the concrete with hot water at the plant. They will consider the outside air temperature and travel time for delivery to make sure the temperature of the concrete is still warm enough when it arrives at the construction site.


Since concrete sets extremely slowly—or not at all—in cold temperatures, suppliers will add accelerators to the concrete mix to speed up the setting time and prevent the concrete from freezing. Some accelerators include calcium chloride, which speeds up the hydration reaction in concrete. There are also non-chloride accelerators available. The type of accelerator your concrete supplier uses will depend on your concrete project needs.

Extra Cement

Concrete suppliers may also add extra cement to the mix to increase the hydration reaction. This reaction generates more heat, leading to a hotter concrete that will set faster and is less likely to freeze.

Avoid Slag & Fly Ash

Since slag cement and fly ash generate less internal heat and set slowly compared to other concrete materials, concrete suppliers may not use these two materials in concrete mixes during the winter. These materials are more prone to freezing and are not able to set in cold temperatures.

Extra Considerations

Additional tips concrete suppliers will follow for concrete projects in winter include:

  • Using entrained concrete to reduce bleeding;
  • Specifying the slump at less than four inches;
  • Being cautious with water reducers—they may not be necessary; and,
  • Avoiding the use of admixtures onsite if they have frozen.

Although concrete construction projects in winter are not ideal, they can be done. With the expertise of concrete suppliers in Ottawa, you can have a concrete mix to suit your project needs in cold temperatures. These concrete experts will create a special winter mix that will stay warm and set faster, so you won’t have to worry about your concrete freezing and losing strength.