Concrete: The Importance of Setting and Curing
One of the most important areas to understand about concrete is the distinction between setting and curing – because knowing the difference means you can help extend its life by many months. Madmix supplies high-quality accredited concrete from its base on the outskirts of Cambridge. Here, we explain the meaning of these terms.
Setting
Concrete is said to have ‘set’ when it has stiffened to the point at which it can absorb pressure without suffering any damage. One way of testing this is to walk on the new concrete surface. If you don’t leave any footprints behind, then the concrete has set.
Although the length of time this will take varies, depending on the type of mix and the weather conditions at the time, generally it will take at least two hours for the concrete to set. Typically, it sets more quickly in hot weather, while in very cold or freezing conditions it can take up to 20 days for this process to be completed.
Once the concrete has set, then it is no longer workable. If you do need it to be workable for a longer period of time, perhaps because it is being used for a large, long or complicated project, then a special retardant can be added to your concrete mix.
What if it Sets Too Quickly?
If the concrete dries out too quickly, either because the temperature is too hot or because its initial consistency is too wet, then it won’t reach its optimum strength. This means it may be vulnerable to cracking, surface erosion and other forms of ordinary wear and tear. Its overall lifespan may also be shortened.
This is why curing is necessary even after the concrete has set. Curing is the process controlling the loss of moisture from concrete once it has been put in position. This allows a chemical reaction known as hydration to continue to take place. Chemical compounds such as calcium-silicate hydrate (C-S-H) are formed, and these are responsible for as much as 90% of the mixture’s final strength.
How You Can Cure Concrete
There are a number of ways to cure concrete. You can keep the surface moist by sprinkling it either with water, a special curing compound. or a damp material such as sand or hessian.
Alternatively, it can be covered with a protective surface. At Madmix we recommend covering your concrete with polythene, which ensures that the moisture already present won’t evaporate too quickly.
As with setting, the speed at which concrete is cured will vary, depending on the composition of the original mixture and the weather. We suggest leaving any polythene sheets in place for seven days in summer, and for 10 days in winter. In very cold weather, where there is a risk of the air temperature freezing, an air gap can be left.
Accredited Concrete from Madmix
Madmix deliver a wide variety of accredited concrete to customers in the Cambridge area, including to addresses in Ely, Huntingdon, Royston, St Ives and St Neots. We have been given the BSI kitemark, which is only awarded to companies whose concrete meets the BS EN 206 and BS 8500-2 standards.
Our website has a concrete calculator so you can easily work out how much you will need for your project. And if you have ordered too much, we can take away any excess at no extra cost.
If you would like to know more about our products and services, or need some advice about concrete setting and curing, follow this link, or you can call us on 01954 212212. You can also email us at info@madmix.co.uk.
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