How long does concrete take to set?

The quick answer to this question is, if you want to know how long before the neighborhood kids can’t leave finger prints on your new paving, in about 24 to 48 hours. The truth is Concrete never actually cures 100%. It will always be in a state of hardening.

For concrete there is no Cure!

The continual hardening or referred to as ‘Curing’ occurs because cement particles react with the water in the mix (hydration), and as long as cement is in contact with moisture, even minuscule bubbles, it will continue to form bonds. That is one of the reasons that the cement is kept wet for the first few days. It is a very small amount after “full strength” is achieved, but it is continual.

A delicate balance

Moisture plays a critical role in curing time for concrete. If there is not enough water in the mix, the concrete will cure too fast, resulting in weaker overall strength. Where there is too much moisture, it will cause weakness in the top layer and cause flaking of the concrete floor. In South Africa, hot ambient temperatures and windy conditions accelerate the evaporation of moisture–speeding concrete setting time and making it a very difficult process for 100% concrete floors.

Why is rib and block the answer then?

Suspended slabs is a recognised and proven system for construction in and around South Africa.  The benefits of the use of precast pre-stressed slabs are mainly quicker and easier construction, a reduction in site problems and overall supervision and greater confidence in the slab structure. It is time saving and economical.Because of the slabs being precast, there is a massive reduction in time spent on curing and overall cost of getting a floor installed is reduced.  With new technical developments and improved construction management techniques we are  ensured that this is a sound and viable form of construction for the 21st century.