Waiting for concrete to dry?

Concrete drying time is an issue for toppings, impermeable coatings, and floor coverings

There are many situations where concrete slabs and elements must be completely dry throughout before application of further coatings, toppings, or coverings.

Did you know that concrete dries at the rate of 25mm depth per month? That’s not from when the concrete was poured – it’s from when it was last wet. (Been raining over your way?)

Internal moisture in new concrete

MARKHAM has been dealing with this issue for about 25 years now; it is commonly seen when installing large-footprint vinyl floor coverings, e.g. in a supermarket, and the construction schedules are too tight to allow proper drying of the concrete substrate.

However the issue can occur under any impermeable coating. Lately we’ve seen it crop up in the mining industry, where industrial-grade coatings are applied for acid protection – but the concrete must be dry first!

It’s not just about curing!

As long as the slab or element is exposed to rain and external moisture sources, it will not be properly drying. Effectively, the drying process should be calculated from the date the slab is protected from the weather (weathertight). In the case of exterior elements, this simply isn’t possible. For these reasons, the time until the safe application of coatings or coverings is often underestimated – resulting in a very high risk of failure.

So what goes wrong?

The remaining free moisture in the slab can still move through the porosity of the slab, and can still evaporate as moisture vapour. Once the surface has been ‘sealed’ with a coating or covering, a certain amount of ‘moisture balance’ movement occurs within the slab, and moisture movement increases. Moisture vapour forces its way out of the surface of the slab and potentially creates bubbles beneath the coating.

What is the solution?

When high moisture levels are found, the typical response may be to apply a coat-on moisture barrier. This is usually an unplanned expense for the project team. Conversely, the construction team may simply be forced to wait – triggering knock-on delays and associated expense.

For best results, to avoid the unexpected expense and maybe even make some savings in other directions – apply concrete hydrogel treatment.

Nanoparticle silica concrete hydrogel treatments are unlike a traditional coat-on moisture barrier. The treatment binds up the free moisture in a hydrogel formation, deep into the concrete porosity. There is no surface coating – no compatibility issues – no risk of the treatment being worn away.

In fact, if applied early, the treatment can also replace the curing compound or water curing process. This is a significant saving in time and money.

Do yourself a favour

This is a serious no-brainer. Save money. Save time.

Talk to the friendly MARKHAM team about your next concrete project!

MARKHAM treatments are used on an average of 50,000 m2 of concrete every month across Australasia. Put our experience and systems to use in your project.

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