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Cold Weather Concreting Tips and Precautions to Follow

Cold weather concreting is the concreting performed at lower temperatures. As per ACI 306, a concrete is classified as cold concrete, when:

  • The concrete is exposed to an average daily temperature of less than 5oC
  • The concrete is exposed air temperature is not greater than 10 degrees for more than one-half of a day.

The article explains some tips to be followed while performing cold-weather concreting.

Fig.1. Cold Weather Concreting; Image Courtesy: Herbert Construction

Tips for Pouring Concrete in Cold Weather

When the concrete is poured in cold weather, special care must be taken to avoid freezing just after the concreting. Care also involves providing sufficient heat to the concrete to promote the hydration process of concrete. This way, the concrete attains the required strength. 

The below-mentioned steps must be followed to performed cold weather concreting to obtain the required design strength. 

  1. Start the concreting activity by defining the strategies required for cold weather concreting and the materials, formwork, testing, and other requirements.
  2. The cold weather protection measurement of the concrete mix must be scheduled and determined.
  3. Prepare a well-defined temperature record chart that specifies both the concrete temperature and exterior temperature. 
  4. Do not pour the concrete on a ground that is frozen with snow or ice. Heaters can be employed to thaw the ground base before pouring the concrete.
  5. The concrete must be protected for specific temperatures based on the strength requirements.
  6. Check whether the heat enclosures used for placing the concrete in cold weather are windproof and weatherproof.
  7. If the concreting employs combustion heaters, prevent carbonation by venting process.
  8. The cold weather concrete designed must possess a sufficient amount of air entrained voids to resist the freezing and thawing effects.
  9. The cold weather concrete mix possesses a lower slump value and lower water-cement ratio so that bleeding and setting time can be decreased.
  10. Curing blankets can help prevent freezing and maintain the curing temperature.
  11. The use of insulation blankets can help maintain the concrete temperatures above 50 degrees celsius for three to seven days.
  12. The final finishing of the concrete surface must not be performed when there is bleeding water above the surface.
  13. Take special care not be let the temperature of concrete below 40 degrees celsius in 24 hours.
  14. Start sealing the fresh concrete when the setting process has started. 
  15. The concreting must be performed as soon as possible. If the batching plant and the final concreting destination is far, special care must be taken to reduce setting issues.
  16. Around 50% of the potential 28-day strength is reduced when the fresh concrete freezes.

Maintain Concrete Temperatures During Cold Weather

The temperature at which the concrete must be placed and protected during cold weather are recommended in ACI 306. The code serves the objective to keep the concrete warm ( temperature greater than 5 degrees Celsius ) for the first two days ( strength development period).

When the concrete is placed at a temperature below 5 degrees ( temperature not less than freezing point), it takes longer to attain strength.

The formwork must not be removed when the concrete is too cold. The use of frost blankets and insulated blankets is one remedy to protect concrete. Beams, columns, and walls can be covered with insulated forms or temporary covers to perform curing.

Also Read:

  1. Top 15 Factors Affecting Strength of Concrete
  2. Stainless Steel Tying Wire In Construction

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