Factors to Consider When Using Concrete in Freezing TemperaturesDecember 20, 2016
The cold winter weather will be with us for a few months longer, so if you plan to be working with concrete at all this season, you’ll have the extra pressure of freezing temperatures to contend with.
Although this can prove difficult for any commercial or domestic project, there are some steps you can take to make sure that your concrete doesn’t end up compromised by the cold.
Concrete in the cold
We talked last month about the effects that the cold can have on concrete. The main threat posed by freezing temperatures is early freezing of the mix. If this happens, the mix will be severely weakened and rendered unusable. You want to avoid this at all costs.
There are many different mixes of concrete to suit specific projects, and these aren’t purely decided by the water-cement ratio of the concrete. Admixtures can be introduced during the mixing process to give the mix extra properties. Typically, these include things like added strength or improved workability, but you can also use admixtures to increase the setting rate of the concrete. These are called accelerators.
Concrete will set much slower in the cold, but adding accelerators to the mix will help to reduce the chances of premature freezing.
If you’re planning to pour concrete in the cold, discuss the mix with your supplier and they will be able to advise on the use of accelerators and other admixtures well in advance.
Plan your pour in advance
While the weather will be more predictable this time of year, there’s still room for things to change and some days will be better suited to pouring concrete than others. Keep an eye on the forecast and try to arrange your pour for as warm a day as possible. Keep in contact with your supplier and get the delivery date booked early on. Giving plenty of notice will work to your advantage should conditions suddenly worsen, and your supplier will be more likely to rearrange things for you if it’s too cold to pour concrete or if your site isn’t properly prepared for the drop in temperature.
Prepare your site
Whether it’s a smaller domestic worksite or a large scale construction site, you should prepare the area of the pour for adverse conditions.
Your subgrade is one of the most important things to maintain – pouring concrete on a frozen subgrade should always be avoided. You can work to stop this from happening very early on, even a few weeks before the pour, simply by covering the subgrade with frost blankets and keeping it covered until it’s time to pour.
You can also bring in heaters to warm the ambient temperature, or close off the site to prevent cold air from infiltrating into the pour site.
Discuss the conditions with your supplier
Using a professional concrete supplier means you don’t have to leave things to chance. Discuss the prevailing conditions with them and they will be able to help you prepare for the cold. Enquire about the use of hot water in your mix – your supplier will likely default to this if the temperatures threaten to drop – and discuss how best to protect the concrete before, during and after the pour.
You can also discuss the best delivery options, as well as asking for advice specific to your kind of worksite – a concrete supplier will have vast experience working in a range of worksites, both domestic and commercial.
Insulation is highly recommended during the curing process, so cover your slab with blankets to retain heat. It’s also recommended to leave your formwork in place for as long as you can to encourage a more even distribution of heat. This helps the concrete to maintain a better temperature for longer while it cures, giving it the best possible chance to attain its necessary strength.
When it’s time to remove insulation after the curing process, do so slowly. Try not to expose the concrete to a sudden temperature drop, known as ‘thermal shock’. A gradual cooling of the concrete will help to prevent against cracking, so remove blankets, heaters and formwork bit by bit, instead of all at once.
EKA Concrete have over 20 years of experience in supplying high quality concrete to a wide variety of clients throughout the South and South East of England. Our reliable and knowledgeable team are on hand to offer specific advice to aid your project, using their expertise to ensure a successful project whatever the weather. For more information on any of our services, don’t hesitate to get in touch with us today.This entry was posted in concrete, concrete tips. Bookmark the permalink. ← Best Practices for Pouring Concrete in Cold Weather How to Avoid Concrete Blowholes →