The British weather is famously unpredictable. This means that you can’t always be sure that the sun will be shining when you decide to pour concrete. Cold temperatures can have a big impact on freshly laid concrete, causing it to become damaged and useless. Read on to find out how to pour concrete in cold weather.
What are the risks of pouring concrete in cold weather?
Pouring concrete in cold weather is often unavoidable, particularly if you’re rushing to finish a project to a deadline. However, there are risks involved in doing so, with low temperatures impacting the quality and condition of the poured concrete. If the concrete is allowed to cool below freezing point, it may be damaged to the point that it will be unfit for use.
When temperatures drop, the chemical reaction that strengthens the concrete slows down, leading to weaker concrete. Below freezing, the water inside the mix can freeze and expand, leading to cracks, scaling, and crumbling. This can lead to an unsightly and substandard job. Even if the temperatures don’t fall below zero, the concrete will still develop strength at a much slower rate than if it were laid when the weather is warmer.
What counts as cold temperatures?
Many people wonder what counts as cold temperatures when laying concrete. Usually, this refers to temperatures below 5°C. In the UK, the weather usually reaches these temperatures any time between October and February. Fortunately, temperatures don’t fall below freezing very often, with extreme winter weather a rare occurrence. You can still pour concrete in cold weather, as long as you follow the correct procedures.
Protect concrete from freezing
Protecting your concrete from freezing is imperative during the first 24 hours. Since water makes up much of the concrete mix, ice could form, with expanding water crystals disrupting the hydration process. This can lead to the concrete losing as much as 50% of its strength. If newly-poured concrete freezes, immediate and permanent damage can occur.
Let the ground thaw
Before you pour the concrete, it’s vital to let the ground thaw. Don’t risk laying the mix on top of ice or frost. On the day you plan to pour it, check that no frost has formed overnight. Inspect the cavities and trenches in the ground carefully. One step worth taking when pouring concrete in cold weather is to lay down thermal blankets the night before. This will insulate the ground, helping to stop ice from forming.
You may also choose to use special industrial heaters to hasten the thawing process. If you do use heaters, they should be vented and not positioned in a way that directly heats or dries out the concrete.
Concrete surfaces which are exposed to carbon dioxide released from unvented combustion heaters can be damaged by a process known as carbonation. Carbonation happens when carbon dioxide reacts with the cement hydration products, leading to surfaces becoming soft and chalky. Unvented combustion heaters also create carbon monoxide which is harmful to workers.
Lay thermal blankets and use windbreaks
When the weather’s cold, you may choose to lay thermal blankets over the poured concrete. Concrete blankets are very effective at keeping the concrete warm during the curing process. In fact, these blankets can help concrete remain at an ideal temperature, even when temperatures drop below freezing. You should use thermal blankets to maintain the correct concrete temperature for three to seven days.
After around a week, the concrete will have gained roughly three-quarters of its compressive strength. Some people also choose to use windbreaks if the wind temperatures are particularly cold. T
his can add further protection to your concrete when pouring it in cold weather.
Remove the insulation or heaters gradually
Once the concrete has set, it’s important to remove the insulation heaters gradually. This lets the surface temperatures cool slowly over the next 24-hours. If you remove the protection too quickly, the concrete may cool down too rapidly, creating thermal gradients that can cause surface cracking. Consider leaving the protection in place and slowly reducing the sources of heat until the concrete temperatures begin to match the average air temperatures.
Add water to concrete
There is a simple solution to ensuring that freshly poured concrete doesn’t freeze in cold weather – adding water. Combining water with the poured concrete will allow the mix to set in without it freezing. The reason for this is that water creates heat during the hydration process, which helps to prevent the concrete from freezing.
Why hire Doncaster Quickmix
Doncaster Quickmix has become one of the leading concrete supplies in Doncaster and Rotherham over the last 10 years. During the past decade, we’ve helped hundreds of domestic and commercial customers source the concrete they need for their projects, providing a professional and efficient service they can rely on time and time again.
We supply quality, ready mix concrete which is made to your exact specifications. This ensures that it will be ideal for your needs, whether you’re laying a driveway, creating a patio, or building a block of flats. We can cater to all requirements, with no job too big or small for our team to handle. Our fully automated batching plant mixes concrete that meets BS8500 standards. You can rest assured that you’re buying a first-rate product when you come to us.
Hopefully, this has answered all the questions around how to pour concrete in cold weather. At Doncaster Quickmix, we’re proud to be the first point of call for people seeking quality concrete in Rotherham and Doncaster. If you’re ready to discuss your requirements or you need expert advice, don’t hesitate to get in touch. Call us on 01302 972997 (Doncaster) or 01709 807977 (Rotherham) to talk to one of our friendly team. You can also send us a message via the website and we’ll back to you as quickly as possible.
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