Which Type of Concrete Do Contractors Use In Winter?

Dropping temperatures can play a massive role in the day-to-day operation of a construction site.  Concrete temperature monitoring is crucial in cold weather because low temperatures can decrease the rate of strength.  The drop in strength affects the general durability of the structure.  For this reason, you have to make sure that you take consistent readings to ensure that the structure is optimized as much as possible.

The Heat of Hydration & Concrete

The heat created from the curing process comes down to an exothermic reaction.  This reaction is otherwise known as the heat of hydration.  When this reaction occurs, the hydration rate will slow down.  The concrete can then be placed and transported after this point enters the dormant phase, which has not yet hardened and is highly workable.  The dormant period will depend on many factors, such as the type of cement used, the additives added, and the presence of slag and fly ash.

The Initial Strength Gain During Cold Weather

As concrete hardens, the heat generated can last for hours.  The concrete in-situ hardens, and the hydration process begins to slow down.  It is imperative to control the general temperature of the concrete during the setting phase and the dormant phase.  The hydration process can be impacted if the placed concrete gets exposed to temperatures that are too low.  These low temperatures can significantly impact the strength of the final product.  For this reason, companies need to account for this when working with concrete.

Pouring Concrete in Cold Weather

Cold weather in Canada is defined as three or more days of low temperature below 10° C. Concrete temperatures must be maintained above this for 48 hours after pouring.  Concrete surfaces must be covered and protected for the first 24 hours to prevent frost damage.  On top of this, the concrete cannot reach freezing level before 500 psi has been achieved.  If this is not guaranteed, the result won’t be as strong as it could be.

Controlling Conditions

Concrete contractors can use different techniques to maintain an appropriate temperature to ensure the elements are curing as they should in cold weather. One would be to use insulation blankets. These cover the concrete and allow heat to get distributed throughout the hydration process. This heat distribution helps maintain a consistent temperature throughout the concrete as it sets. Another thing that contractors can do is to use a mix with less slump or water.  Contractors can add hot water to the mix, and various additives can be added on top to speed up the curing process and the setting time.

One more approach would be to use concrete designed for cold weather conditions.  Type III cement can generate more heat than type I and type II. Using finer cement will also help to generate heat, which is beneficial when working in very cold conditions.

Conclusion

If you have any questions about cold weather concrete or our other services, please don’t hesitate to contact the experts at Garden Concrete today!

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