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Concrete Floors and Construction Moisture

What are the risks and what is the solution?

Concrete Floors and Construction Moisture

In the construction of new buildings, it is common practice to apply floor coverings directly to concrete floor slabs.
Markham saving the world one concrete structure at a time
Unfortunately, floor failures due to excess moisture in concrete are a common occurrence. This is largely due to the impact of tight construction schedules.
Excess moisture within the concrete beneath floor coverings can have other negative effects as well, creating a haven for mould and bacteria, with the resulting odours and impact to occupants’ health.
Markham saving the world one concrete structure at a time

Let’s talk about floor slabs

Concrete is about the most commonly used building material on the planet, due to its comparatively low cost, innate strength, and versatility of application. Its use for floor slabs is as ancient as the Romans. Direct-stick flooring is of course much more recent, a common and very practical compromise between budget and durability.
Markham saving the world one concrete structure at a time
When a slab is poured, it must cure over a certain period before floor coverings can be applied. The process of curing involves the evaporation of much of the internal moisture. Usually about 28 days from pour is allowed for this purpose.
Importantly, ‘curing’ is not the same as ‘drying’.
In fact, a concrete slab dries at the rate of about 25mm thickness per month. This means that after a period of 28 days, slightly less than 25mm will have dried, and the internal moisture levels may still be high. A 125mm thick slab may take 5 months to dry to RH of 75% or less.
Markham saving the world one concrete structure at a time

Retail floor slabs need protecting against moisture movement

It’s not just about the curing!

As long as the slab is exposed to rain and external moisture sources, it will not be properly drying.
Markham saving the world one concrete structure at a time
Effectively, the drying process should be calculated from the date the slab is protected from the weather (weathertight).
For these reasons, the time until the safe application of floor coverings is often underestimated – resulting in a very high risk of failure.
Markham saving the world one concrete structure at a time

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 floor coverings have been laid, a certain amount of ‘moisture balance’ movement occurs within the slab, and moisture movement increases. Moisture vapour forces its way out of the top surface of the slab and either creates bubbles under resilient floor coverings or dissolves/dilutes the flooring adhesives.
Markham saving the world one concrete structure at a time
Then there’s that health point mentioned earlier. Bacteria, mould or fungus grows in moisture trapped between slab and floor coverings, with potential health risks to the users of the building, to say nothing of a bad smell which can’t be cleaned away.

Retail floor slab under vinyl

Markham saving the world one concrete structure at a time

What is the solution?

When high moisture levels are found by the floor layer, the typical response is to apply a coat-on moisture barrier. This is usually an unplanned expense for the project team.
Markham saving the world one concrete structure at a time
For best results, to avoid the unexpected expense and maybe even make some savings in other directions – apply concrete hydrogel treatment.
Markham saving the world one concrete structure at a time
AQURON 2000 and AQURON 2000 Medi+ 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.
Markham saving the world one concrete structure at a time
In fact, if AQURON 2000 is applied early, it can also replace the curing compound or water curing process. This is a significant saving in time and money.
This is a serious no-brainer. Save money. Save time.
Talk to the friendly Markham team about your next construction project!

Download free information on concrete treatments beneath floor coverings





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