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Precautions for Cold Weather Concreting

Extreme cold weather conditions can significantly affect the quality of concrete, as well as its mechanical properties. In cold weather concreting, one should make sure that all the negative impacts of low ambient temperature are appropriately alleviated by taking the necessary precautions. In this article, we will review important steps that can ensure you will get the quality you are looking for. But first, let’s see what cold temperature is for concrete, and why it is critical.

cold weather concreting

What is Cold Weather for Concrete?

American Concrete Institute definition of cold weather concreting, ACI 306, is:

1- A period when for more than three successive days the average daily air temperature drops below 40 ˚F (~ 4.5 °C) , and

2- Temperature stays below 50 ˚F (10 °C) for more than one-half of any 24 hour period.

In Canada, where temperatures tend to be much lower during the cold season, the following criteria is used by CSA A23.1:

1- When the air temperature is ≤ 5 °C, and

2- When there is a probability that the temperature may fall below 5°C within 24 hours of placing the concrete.

CSA A 23.1 vs ACI 306 FPrimeC Solutions Cold Weather Concreting


Why Cold Weather Concreting is Challenging?

The hydration of cement is a chemical reaction. Extremely low temperatures as well as freezing can significantly slow down the reactions, thus, affecting the strength growth. In fact, freezing temperatures within the first 24 hours (or when concrete is still in plastic state), can reduce the strength by more than 50%. The minimum strength before exposing concrete to extreme cold is 500 psi (3.5 MPa). CSA A 23.1 specified a compressive strength of 7.0 MPa to be considered safe for exposure to freezing.

Read More: On-Site Evaluation of Concrete Strength

Precautions for Cold Weather Concreting

1- Removing Ice + Snow from the surface of formwork
2- Ordering concrete with temperature between 10 °C - 25 °C
Note: Heating water and/or aggregate is one way of achieving the objective; however, heating cement is not considered as effective.
3- Avoid using Calcium chloride or other de-icing salts
4- Slab formwork temperature

Slab thickness < 1.0 m : 10 °C
Slab thickness > 1.0 m : 5 °C

Protecting Concrete in Cold Weather

5- CSA A23.1 specified that protection shall be provided by means of:

Heated enclosures

Note: The heat generated from hydration process should suffice in most cases, if appropriate insulating blankets of polyethylene sheets are used. Additional source of heat might be required based on area and temperature.

6- Avoid wet curing should you expect the temperature to fall to freezing point
7- The temperature gradient of concrete surface and ambient environment should not exceed those specified in standards, such as CSA A23.1

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7 thoughts on “Precautions for Cold Weather Concreting”

  1. Thomas Haynes, P.E.

    In addition the surfaces upon which concrete makes contact must be above freezing. If this is not done a layer of soft paste can result. This paste layer of damaged cement cannot ever set.

  2. Thank,s for all participants, but one thing which is click in my mind is spatial conditions.for example humidity,wind velocity, vegetation, plants. These all participate in build up a suitable atmosphere.

  3. Pingback: Protecting Concrete in Cold Weather | FPrimeC Solutions

  4. Monitoring of concrete is important to confirm that winter protection measures are sufficient. I supply concrete monitoring system that will cost you around $35 per pour. Please contact if interested. My cell is 6479840247.

  5. I worked on a small (Squash courtyard) project back in 1965 in Riyadh, at winter time, after B.Sc. Graduation.
    The contractor poured concrete slab at 6 p.m., concrete mix had too much water. The ambient temprature was around 10 C, and we left the site.
    Next morning I returned to the site and found the concrete cracked beyond repair.
    The reason was that the temperature fell down to 4 degrees at 7 p.m. and the water within the concrete mix froze and caused the degradation of the slab.
    Hence, protection against cold weather should be taken in what is considered as hot climate regions at certain time

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