Oversite concrete slabs employ a 1000 guage 250 microns polythene sheet laid underneath the concrete to prevent the moisture from being absorbed.
Polythene sheet for concrete slab.
Keep w c at or below 0 5.
Starting with lower water cement ratio concrete will let the slab dry faster.
The general standard employed for the testing and verification of polythene sheets for use as a vapor barrier is the astm4397.
The order upwards for the slab is.
However this list is a summary of current applications.
As polyethylene is a relatively new plastic scientists are busily exploring and developing new applications for the products.
Today most experts feel very strongly that engineered films designed specifically for use as vapor retarders should be used as vapor retarders.
Vapor barriers also block gases such as methane or radon.
A concrete vapor barrier is simply a sheet of polyethylene plastic visqueen placed directly on top of the sub grade before the concrete floor or slab is poured to help keep moisture from the soil from passing up through the concrete.
A vapour barrier in concrete slabs full basements and crawl space construction.
Polyethylene sheeting under concrete slab.
Under slab vapor retarders play a very important role in retarding moisture from coming up through the concrete and into the structure.
Undisturbed soil crushed stone 4 inches of type i eps 6 mil polyethelene sheet another 4 inches of type i eps and then the 4 inch concrete slab for a total insulation value of r30.
This is because polyethylene allows the passage of oxygen and carbon dioxide.