We use dimpled membranes mainly for the mechanical protection of basements waterproofing layers.
In some countries e.g. Canada these products are used as the main waterproofing product.Audacious undertaking I have to confess!!
Today we will analyse two not very prevalent uses of dimpled membranes
1.Dimpled membranes as vapor barriers under ground floor slabs
This is a very clever application to replace mechanically vulnerable polyethylene films.g>
I use HDPE dimpled membranes of at least 25tn/m2 with great success for this application. Many times I combine vapor barrier with lean concrete replacement. Thus we kill two birds with one stone!
The product is unrolled on leveled ground after we place and compact 10cm of washed gravel on a geotextile. Dimples (knobs) should face downwards.
I use an overlap of about 15cm. Sometimes I seal the overlaps with MS Polymers or proprietary tapes, sometimes I dont.
This is not of utmost importance since water vapor cannot move freely between dimpled membrane and concrete. Only if free movement existed, the sealing would be imperative.
This HDPE product is much more robust from a polyethylene foil.
2..Dimpled membranes to replace lean concrete
This is an application rapidly gaining ground in Europe
My experience from such applications is excellent.
There are very concrete advantages in this kind of job:
1. Absolutely less cost
2. Quicker job. No dependency on weather
3. Clean job
4. HPDE membrane could also work as vapor barrier. Just seal the seams with the appropriate butyl tape.
How to use
Substrate should be level. A layer of gravel could be needed. Choose a membrane with a pressure resistance of at least 25tn/m2. Dimples should look downwards. Successive layers should have an overlap of 15cm. The surface is ready to accept the slab reinforcement.
Dimpled membranes are perfectly accessible to workers and wheelbarrows
Chris Strogilis
http://maconwaterproofing.blogspot.com/
About the Author:
Civil engineer with postgraduate studies in MBA and Marketing
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