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Re: Water Proof Membrane

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Rich,

I could spend several hours answering your questions, I could do my own work, or I could go shopping for new curtains.  Needless to say,  answering all your questions is not in the running.

As a short answer - if I had a job where the owner did not want to spend much money and the leakage was not that significant,  I would probably just put a sealer on the slab, without doing anything about the cracks.  Sealers are not able to stretch, so if the cracks open up, there may be some leakage, but there will be less.   I would try to have it sealed on a cool day, and early in the morning so that the sun had not been beating down on it.  The cracks will close to their widest - if you get them sufficiently full of sealer, you may actually stop all the leakage.

I don't have any strong feelings in the silane/siloxane debate.  Siloxane molecules are bigger and therefore are theoretically better for larger pores.  Typically siloxane is specified for sealing masonry.  For concrete, I would specifiy:

a.  Enviroseal 40, Hydrozo Inc.;
b.  Baracade Silane 40, Tamms Industries ;
c.  Penetrating Sealer 40, Sonneborne ; or equal.

All three of these products have been around awhile and are specified a lot by other engineers.  All three are silanes, the 40 indicates 40% solids which people seem to agree is the magic number for silanes.

I would emphasize that this is the low cost option,  the only thing lower in cost would be to do nothing.  There are probably dozens of other options, when you consider all the  different combinations of crack repair and waterproofing products.  All will be more expensive and some may only result in a limited improvement as far as stopping the leakage.

But there lots of other things you will need to address.   For example, you probably need to specify what is required for surface preparation - water blast, sand blast, shot blast or simply scrubbing with soap and water.  Soap and water may be fine,  in which case it is a waste of the owner's money to require shot blast.  If you have oil or grease stains, you will probably need to use a special degreaser.  Using any kind of acid is not really recommended for surface preparation because unless you really do a good job of subsequently removing it, you will have problems.

And again, I don't want to blast anyone for asking questions, but my personal feeling is that when there is a problem with a concrete repair, it is usually because the engineer has no idea what he or she is doing.  

The best way to learn repair is to work with someone who knows what they are doing.   The second best way is work with someone who doesn't know what they are doing are learn from their mistakes.  The worst way is to have to learn from your own mistakes.   

Gail Kelley