Concrete Sweating: Causes & Prevention

Why is concrete sweating?

When warm air in the atmosphere meets cooler concrete, condensation (water droplets) form on the concrete, which is known as concrete sweating or Sweating Slab Syndrome (SSS). It usually happens in hot and humid weather. A sweating concrete floor can be a significant inconvenience that can create a slippery surface and make the floor damp.

What are the causes of concrete sweating?

The concrete sweating is mainly due to the temperature difference issue. But there are other causes of concrete sweating which will be discussed as below: –
  1. Concrete reaching dew point – If the air cools to or below the dew point, it begins to condense on the surface of the concrete, resulting in a wet and sometimes misty appearance.
  2. Due to wet adjacent soil – In the structure such as retaining concrete wall, breast wall which has a wet soil on the other side of it. Despite the fact that concrete is a solid, hard, and dense material, it contains minute capillaries that allow water droplets to move from one side to the other, causing the concrete to sweat.
  3. Density of concrete slab – This is caused by the pour back strips inside the tilt-perimeter. When tested, a pour-back strip’s porosity is generally found to be greater than that of the main floor. The most likely reason is that pour back strips are frequently not finished in the same manner as the main floor and may not have received the same sealer/densifier treatment as the main body of the slab.
  4. Concrete slab cleanliness – The cleanliness of the slab is another potential contributing factor. Surface permeability can also be reduced by a slab surface covered in black rubber tire marks or exhaust deposits. Not only does a less permeable slab surface absorb less moisture from above, but if an effective vapour retarder is not installed beneath the slab, moisture levels within the concrete and near the slab surface will rise over time.

How to prevent from concrete sweating?

  1. Strong air movement – Start by using a high volume, low speed fan to move the air around the room in an effort to dry it out.
  2. Turn on the heat – Control the temperature by lowering the air conditioning or increasing the heat to maintain a consistent temperature between the air and the concrete floor.
  3. Use dehumidifier – A dehumidifier can be used to reduce air moisture.
  4. Use sealer – Use a penetrating sealer to protect the concrete and keep moisture out. A concrete densifier should be used first to apply a stain repellent to the concrete.

Key Takeaways

If you’re not used to dealing with concrete then witnessing your concrete sweat for the first time might be alarming. Although concrete is a superb building material, the presence of concrete sweat can potentially result in several possible problems and expenditures including dealing with mold and mildew.

Once you understand why concrete sweat forms, you may take activities to help fix the problem. Managing sweating slab syndrome can create safer circumstances and prevent trouble in the future.

Please do not hesitate to contact us if you require more information. Our team will be happy and glad to assist you.

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