Concrete setting time
Here we leave you a post that talks about the setting of concrete.
Drying the concrete or technically called as curing is the main concern after pouring the concrete. It is this step that will allow the concrete to achieve its capabilities.
These are strength and durability. Just as the proportions and manner of making concrete is important, so is how long it is allowed to dry and under what conditions.
Concrete drying time is characterized by two important dates when tests are performed to verify the quality of the concrete:
- Test after 7 days
- Test at 28 days
We will see that multiple factors influence the drying time of concrete, such as external conditions, type of concrete, quality of concrete: water content, quality of aggregates, type of additives. But the most important factor is its field of application.
The compactness of concrete is a value that is often indicated by a “c” to determine the void volume contained in a material. It is simply the relationship between the apparent volume of the object considered in its actual volume (without the voids).
How to dry concrete properly
The drying time of concrete, whatever it is, is regulated by the standards NF EN 206-1. The curing of the concrete (in other words, its hardening) is the last essential step in order not to neglect to obtain the desired characteristics.
This last step requires special attention and should be carried out as homogeneously as possible.
It is obvious that waiting for the deadlines indicated in the standards, for optimal drying, is rarely respected on construction sites.
However, minimum lead times are recommended before work is resumed to ensure future strength characteristics of the concrete and to prevent the newly poured slab from collapsing under its feet.
The concrete will have reached its class resistance in 28 days and, as there is no concrete drying system, you will have to be patient and simply wait for the recommended times.
Precautions when setting concrete
If the temperature increases, the concrete will set faster! And contrary to what you might think, it’s not always a good situation. Taking too fast can result in a long-term loss of strength.
Hydration solutions or even cooling of the structure can be implemented, so it will be necessary to regularly water the surface of your concrete or provide refrigerated slabs. Yes, even your concrete can catch a hot shot!
In the event of frost, the concrete curing process can be negatively affected and its adjustment slowed down. It is necessary to refer to the regulatory texts they contain and to indicate the procedure to be followed in the event of a sudden drop in temperature.
Namely, the impact of temperature around 5°C can extend the concrete setting up to a factor of 5! It is for this reason that the implementation of concrete at a temperature lower than 5°C is prohibited.
Risks of improperly set concrete
In addition to the loss of strength mentioned above, the worst consequences that can lead to a poor curing of a concrete is, of course, the long-term cracking of the structure.
And, unfortunately, this pathology of concrete is very common, but it should not always be put on the back of a poorly dried concrete. Many other factors come into play to explain the appearance of these cracks.