POURING CONCRETE IN COLD WEATHER
When supplying ready mix concrete in London you can never be sure of the weather, the rain may pour, the sun may shine, and in the winter months your construction site may get hit with cold temperatures. Over the last few years the coldest months have tended toward January and February. In fact in 2017 some weather forecasts predict temperatures as low as -5°C! Freezing temperatures can have a big negative impact on freshly laid concrete, so now is as good a time as ever to read our top tips to help you correctly pour concrete in cold weather.
WHAT COUNTS AS COLD TEMPERATURES?
Concrete is described as being exposed to cold weather at any temperatures below 5°C, for longer than a period of 24 hours. In London the weather usually reaches these temperature ranges at any time between October and February.
DON’T FREEZE!
Luckily we aren’t in the Arctic and London will mostly avoid extreme cold weather for long periods of time. Therefore it is normally fine to lay concrete in cold weather in London as long as you follow the correct procedures and protect the concrete as much as possible.
Freshly laid concrete must be protected from freezing for at least the first 24 hours. Because water is a main component of any concrete mix it is very important that concrete being laid in cold weather is protected as much as possible from freezing after it is poured. If ice forms in your fresh concrete mix it is likely that the expanding water crystals will disrupt the cement’s hydration process, and can cause the concrete to lose up to 50% of its designed strength.
PROTECT YOUR CAVITIES!
Concrete must not be poured on top of ice or frost, so before the pour allow the ground to thaw. On the day of the concrete pour your trenches and cavities must be checked for frost that may have formed overnight. In the day leading up to your concrete pour you can prevent ice or frost forming in your cavities by laying down thermal blankets to provide insulation. Building site heaters can also be used to speed up the thawing process.
PREVENTION
To ensure your concrete does not freeze you should take extra precautions if temperatures are below 3°C. Lay thermal blankets over freshly poured concrete, this will help to capture as much heat as possible that is created during the curing process. If the wind temperatures are very cold it is also worthwhile to build a windbreak around the concrete to add further protection.
FINAL CHECKLIST
Finally, follow our checklist below to help you prevent your concrete pour from any complications. As always we recommend consulting with your building contractor who has intimate knowledge of your site, or Contact Us today if you have any further questions, we’re happy to help!
- Plan Ahead: Check the temperature the day before and on the day of your pour.
- If temperatures are likely to be below 3°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 forming overnight.
- Protect freshly laid concrete with thermal blankets and windbreaks (if necessary)
- Don’t let your concrete freeze within 24 hours of being poured.
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