Waterproof Portland for parging


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Old 08-28-05, 04:42 PM
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Waterproof Portland for parging

I asked for waterproof portland cement at my rockery and I just got a blank stare (actually this happens a lot). Does it go by any other other name or designation or is this a really unusual product?

Thanks
 
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Old 08-28-05, 06:08 PM
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Waterproof Portland for parging

There is no such thing as waterproof portland cement. Mixtures are made waterproof by adding materials to a Portland cement/sand mix and applying them properly.

For parging, you can use a 3:1 (sand ortland cement) mixture. Add a latex modifier (Acryl 60 by Thoro Products) to increase bond and densify. Mist afterwards frequently for several days to improve the coating.

For a premium material you can try Thoroseal (about $30 for a heavy ???lb bag). Apply like pancake batter to a wet masonry or concrete surface.

I don't know what you are trying to seal. but if it is a basement I have another suggestion: Do not just rely on the material on the outside for water proofing. Make sure you have a properly installed drain tile system - it is the cheapest insurance you can have.

Good luck.

Dick
 
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Old 08-28-05, 08:41 PM
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Just a retaining wall. Doesn't matter if it leaks but it's not good for a block wall to be constantly exposed to moisture? I have a drain field on the upslope side and weep holes.

Must be an editing error in Dick Kreh's book because he says to ask for waterproof cement.
 
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Old 08-29-05, 10:09 AM
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Waterproof Portland for parging

If you are talking about a segmented retaining wall, it is not the same thing as a concrete block wall.

A block wall is a rigid structure built using mortar and block. While codes and standards do not require coating or waterproofing, they are frequently coated.

A segmented retaing wall is made from block that look like ordinary concrete block, but the structure acts diffferently from a rigid wall that traps moisture behind it. Construction specifications for segmental walls frequently impose durability requirements on the units that do not exist for common concrete block.

It is not necessary to coat the back of a properly constructed segmental retaining wall. You have drain tile and weeps to drain the area behind the wall. I see no benefit in coating the wall.

You are correct - it must have been an editing error or a poor choice of terms in the book. Frequently, people refer to "cement" when they mean a blend of Portland cement and other materials.

Dick
 
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Old 08-29-05, 09:05 PM
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I use "lafarge type S waterproof cement" for blocks, is this what you are looking for?
 
 

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