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Hypertufa Crumbling

17 years ago

Some of the things I have made of hypertufa have either crumbled or broken. Can anyone tell me what could cause this or is this something that happens to everyone. I think maybe I did something wrong. I used the bag of concrete with peat and perlite. Some things held up well during the winter but I made several different batches.

thanks,

KathyAnderson

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Comments (5)

ladylong
17 years ago
Hi Kathy,

I'm a newbie myself, but I have a guess. If you used concrete instead of cement, your mixture was too weak to hold together. Concrete is cement mixed with other stuff.

The usual "recipe" for concrete is 1 part cement to 2 parts sand and 3 parts aggregate. So when you buy concrete in the bag, the cement is already diluted 5 to 1 because it's meant to be ready to use by just adding water. Adding peat and perlite to that dilutes it even more. Since the cement is what holds everything together, that means your pieces will very lack the strength they need to last.

If you buy straight Portland cement instead of concrete, you can control the proportions of your mix to keep its strength. I've been using roughly one part cement to one part each of sand, perlite, vermiculite, and peat. I haven't been at it long enough to overwinter anything yet, but so far everything's nice and strong.

Hope that helps!
LadyLong
kathyanderson
Original Author
17 years ago
thank you LadyLong,

I just don't like buying all those different things so thought it would be easier to just buy the mix that you just add water to. Then, of course, I added more stuff! I don't have the room to store all those different bags of things. Is there any way I can use that mix and make it work?

Kathy
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daisy_ny6
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Kathie,

A contractors or garbage compactor plastic garbage sacks inside a Rubbermaid lidded garbage can or lidded tub will store the Portland cement safely for a really long time (in my case, years). You can store it outdoors or in the basement or garage. Rubbermaid holds up the best, in my experience; some of the other brands crumble and break within a year, especially when exposed to UV light.

I think it's worth it to get the white Portland cement just because it is so versatile.

If you use PVA fibers instead of nylon or polyester fibers, don't use admix because that could interfer with the cement-PVA bond.
ladylong
17 years ago
Hey, Tufftufa -- I've looked at both HD and Lowe's (several of each) and haven't been able to find the fibers. Are they in a secret place? What should I be looking for?

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