What you need to know
Extra care must be taken when pouring concrete in cold weather. The biggest problem you will face is if concrete is allowed to cool below freezing point, the concrete may become so damaged that it will be unfit for purpose.
It is also important to understand that even if temperatures do not drop below 0°C, the concrete will develop strength at a much slower rate than during warmer weather.
The main problem when pouring at sub zero is if freshly poured concrete cools below 0°C the water in the mix will freeze and expand resulting in damaged and unusable concrete.
The key to a successful pour is for the concrete first to be able to reach a strength of about 2 N/mm2, if this happens it is much more likely to resist any problematic expansion. In most occasions and for most mixes, this strength is achieved within 48 hours if the concrete is kept at or above 5°C. However, even after the concrete has reached 2 N/mm2 low temperatures will slow down the strength development.
During cold weather the most important thing is to keep the concrete warm (above 5°C) for the first 48 hours, then it is important to ensure that the strength is still allowed to develop, at the lower rate associated with cold weather.
Checklist for pouring on cold weather
- Plan ahead: Check the temperature the day before and on the day of your pour
- If temperatures are likely to be below 5°C then make a plan to avoid complications
- Never allow concrete to be laid onto frozen ground, ice or snow!
- Use thermal blankets to help prevent frost from forming overnight and help to retain the heat of the concrete
- Protect freshly laid concrete with thermal blankets and windbreaks (if necessary)
- Don’t let your concrete freeze within 48 hours of being poured
If you need any further advice regarding the placement of concrete during cold weather conditions please do not hesitate to contact our office on 01273 594394