Once placed concrete has to go through a "curing" process as it doesn't reach full strength after the initial hardening.
This simply means that you shouldn't put any weight on it until it's completely cured.
Generally concrete continues to strengthen as time moves on - it never really stops curing, but for a practical strength to be reached most concrete mixes have an advised curing time of 28 days.
After roughly a week the concrete should have gained around three quarters of it's compressive strength but we advise you not to apply weight to it until after the advised curing time has passed (28 days).
Applying weight to the concrete before the advised curing time could result in your work being damaged so it is strongly advised to follow best practice.
Several factors can affect the curing process and how long it takes for concrete to reach full compressive strength, these include:
Typically the curing of concrete is largely dependent on moisture. By retaining moisture content (hydration) the chemical reaction between water molecules and cement will continue.
Concrete will gain strength for as long as hydration takes place. Therefore maintaining the presence of moisture for the duration of the curing process is important. But, on the flip-side, too much water can lead to weaker concrete which is why we recommend taking professional advice on this.
As concrete curing relies so much on the presence of moisture in the mix you can imagine that hot and dry weather conditions could have a detrimental affect on your concrete.
If the weather is too hot and dry then concrete cracking can occur. In conditions like these we recommend erecting a shelter and keeping the concrete damp to offset the effect of hot, arid weather conditions.
Any extremes in weather can adversely effect concrete curing - so inevitably freezing conditions can also have detrimental consequences if pouring concrete during the colder winter months (cold weather can also cause concrete to crack).
When planning concrete pours in winter we would typically recommend choosing days that won't reach a freezing point in the first 24 - 48 hours, however, we also understand that there are things out of your control (unpredictable British weather being one of them).
If you do find yourself pouring concrete in cold weather there are a few things you can do, including erecting a shelter and insulating the concrete to keep forms in place for as long as possible so that heat is distributed evenly.
The curing of concrete is an essential, important process so the type of mix, quantity and application will all affect how it cures. If you need more guidance or just some friendly advice our staff are available to help find the solution you're looking for.