huangyhg

concrete waterproofing help
i'm currently working on specifications for a waste water treatment project. for waterproofing, another engineer recommended xypex or other similar crystalline type admixture for the concrete, though he did not have much else to tell me about it, and i have read what i can find on the web. the structure has large concrete tanks (a number of cells) which are mostly above ground (20' or more) and is required to have a rubbed finish on exterior surfaces. the structure was designed using the requirements of aci-350 and no post-tensioning employed. generally our specs call for coal-tar epoxy on the interior walls, but much of the interior will be exposed and i'd be concerned about its durability under uv besides the aesthetic which is important to the client for this project. the project is large with over 1000cy for just the walls.
1) does anyone have experience with these types of admixtures & their applicability and 2) have a ballbark idea of their cost?

i have not used the product myself, but i have heard about $1.20-$1.50 per square foot, if applied as a slurry coat. it can also be used as an admixture. also check out hey'di k-11, from tamms, a division of euclid. this rep said it was the "next generation" crystalline waterproofer, and that it ran about $1/sq ft applied.
my recommendation is to stay away from "magic coatings." i'm sure xypex does what it says, but most of your problems will be at joints, tie holes and small unavoidable cracks. also, i don't think crystalline coatings work if there is fly ash in the mix.
if the client is worried about the aesthetics of the plant, use a form liner to create vertical ribs or rustications on the outside of the tank. any leaking will concentrate at the ribs and not be as noticeable.
i have had experience with xypex, best if used "in" the concrete mix and should not be used exclusively as your waterproofing agent. if client wants xypex then use in a belt and suspenders approach.
i have had success with bituthene by grace construction products as a waterproof coating.
as the ironman... i've used xypex off and on over probably 30 years and it works really well (usually as a repair). i've not used it as a primary defense. i've also used bituthene successfully... reminds me of the buckley's cough syrup... tastes terrible, but it works... bituthene is one of the uglier, stickier things in life... but works well. also used bentonite materials and they work well. are you looking at keeping things in or things out?
proper control joints with pvc seals work well also; i usually spec the ones that fit flat against the formwork and bridge the joint.
dik

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