# Concrete or hypertufa?



## SE18 (Feb 21, 2008)

In the future, I'm considering doing some rock designs. I'm thinking of screening concrete to remove the larger aggregates or just using cement and sand mix, sort of to do rock work like indoor modelers do with plaster.

But I've noticed that some modelers use hypertufa. What are the pros and cons of each?

I'm thinking that cement might be easier to detail as when making rock facings, as hypertufa looks a bit rough.


OTOH, hypertufa might have some advantages, such as encouraging moss growth. Also, I'm guessing that hypertufa might drain better (allow groundwater to seep through easier) and it also might be easier to punch a hole thru to do a rockside planting.

These are just some hunches I have.


It would be nice to hear from someone who has actually used both materials.


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## lownote (Jan 3, 2008)

Hypertufa is easy to use and to shape and it's somewhat porous, which is good. We made a small "ravine" with it and didn't put any "rebar" in it, so it's broken up. We'll redo it the same way with chicken wire. We had no luck getting moss to grow on it, not sure why


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## SE18 (Feb 21, 2008)

thanks; that was another question I forgot to ask. Would rebar be used to reinforce it like you would concrete. 

Also, would the peat decay over time and cause structural problems


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## derlux (Feb 17, 2009)

This guy from UK build his entire RR with hypertufa.
Really awesome! 

http://www.gscalemad.co.uk/forum/in...topic=2896


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## SE18 (Feb 21, 2008)

derlux 

I saw that site yesterday. I'm not a member of that forum but his work got me thinking and thus the questions I generated. 

I think his site would have looked equally well in concrete. Just a thought. 

His work reminds me of Malcom Furlow, but on a much larger scale.


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## NTCGRR (Jan 2, 2008)

to me chicken wire is too weak. I use 2' X 8" steel lattice cut to fit.


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## tj-lee (Jan 2, 2008)

I've not used hypertufa but I am a big fan of plastic cement for making rocks. 

http://www.mylargescale.com/Features/BuildersLogs/tabid/66/EntryID/12/Default.aspx 

Best, 
TJ


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## R.W. Marty (Jan 2, 2008)

You might find HT a little porus for rock work. It works good for ground and dirt fill between the rock outcroppings.
HT also has a tendency to slightly decompose over the winters, the rain seems to "pock" the horizontal surfaces somewhat.

HT can be made from several different materials and quantity combinations and I'm thinking the different combinations 
will handle the weather differently. I use a recipe of peat moss, plastic cement, and crusher fines. This combination
produces a very good "ground" but does pock from the rain and crack in the dry summer heat. The cracks are no big deal 
as they can be scraped out and called ditches. 

Coloring the HT is also an interesting problem. I have tried mixing concrete color both powder and liquid into the mix water
with varying results. I have also sprayed the mixed color onto the finished HT and that seems to work the best for me, but it 
is like ballast, has to be touched up each year.

I have found that curing HT is a thing that you have to pay attention to. Once mixed and applied it has to be kept wet and cool for several days while it cures. I found the best method was to cover the fresh HT with several layers of bath towels and keep them dripping wet for 3-4 days
then pull them off and then just keep it damp for a few more days. 

I am doing some rock work in a canyon at this time. The form is 1/2 hardware cloth with burlap dipped in plastic cement as the base then rock work applied over that. For the rock I have been using heavy duty tinfoil crumpled up. I have mixed the plastic cement 50/50 with #30 sand and had some pretty goood results. That mixture seems to leave the rock a little grainy, might be alright for sand stone but not for granit. I going to switch to a 75/25 mix and try that. 

Just waiting for the summer weather to pull back a little as it is way to hot to try to cure cement, concrete, or HT.
Hey, good luck with your project.
Rick Marty


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## John J (Dec 29, 2007)

This has been an intereting thread and informative. I have made several notes from it that gave me ideas. I am always looking for ways to build canyons. 
Thanks to all of you.


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## SE18 (Feb 21, 2008)

thanks much all. 

Sounds like the thing to do is combine several techniques, based on each's advantage


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