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Cold Weather Concrete Tips
You can pour in cold weather, as long as certain precautions are taken. Concrete set time at 70 degrees is approximately 5 hours, at 50 degrees it is 10 hours, at 30 degrees it’s up to 20 hours (if the concrete doesn’t freeze!). There are things we can do to “speed things up” and mimic those warm weather set times.
Cold Weather Set-Time Graph
Cold Weather Extends Set Times:
Rule of Thumb: Each 20°F drop in concrete temperature will double the set time.
- Never pour concrete on hard, frozen ground. Try warming the ground with concrete blankets or black plastic for a few days before the pour.
- Call Smokey Point Concrete or Skagit Readymix ahead for advice on what type of mix might work best. Cold weather effects can be countered by:
- Adding an extra sack of cement.
- Adding a chemical accelerator such as calcium chloride or a non-chloride admixture.
- Using heated water instead of cold.
- Using a water-reducer to reduce bleed water.
- All of the above, or a combination, depending on conditions.
- Once the concrete is poured, you MUST protect and cure the concrete for 3 – 7 days. You must use blankets or straw over the plastic to insulate the slab. If you leave the concrete open you could experience:
- The top of the concrete can freeze and pop off.
- If it doesn’t freeze, the top will still be seriously affected, and may NEVER be as durable as if it were protected.
- The overall strength of the concrete may never reach its full potential.
- DO NOT use de-icing salts for at least one year. Use sand instead.
Concrete can be placed, finished and cured to it's proper strength in cold weather conditions if sufficient planning and care are taken. Call Smokey Point Concrete or Skagit Readymix and we will help you be successful!