aye caramba!

that should have read:

The mix was 2 parts sand, 2 parts peat, and 1 parts cement.

Sean,
there are about as many cures as there are mixes.
Cement products cure at 28 days......
That said the initial cure of about 75% is in the 1st 7days, then gradually curing harder from then on. It really doesn't even stop at 28 days. But the 'integrety' of the piece can be damaged if there is not enough water to continue or prolong the cure time.
That said, if you take your trough out of the bag at this point and continue to mist it with water or if it is above freezing overnight where you are and is still raining you can probably get away with setting it out side. since there is a stryofoam container inside I would turn the trough upside down so that the water is hitting all of the tufa'd surfaces.
If you are thinking about roughing the surface of the trough you may want to test the surface with an old ball point pen or pencil to see if you can dent it or scratch it, 5days can be a long time to wait dependent on weather. If it is a little too hard you may still be able to wet the surface and use a harder file or wire brush to add texture.
Hope that helps,
Happy casting,
Dena

"That said the initial cure of about 75% is in the 1st 7days"

That can be untrue, especially at this time of year.
You have to know the curing temperatures before you can be sure of that.

Ahoy,

thanks for the replies.

The temperature is 'room' temperature; say 65F - 70F. From what I'm reading that is a good, temperature to cure concrete in a 'plain vanilla garden variety' kind of way. Which would allow me to assume the majority of cure in the first week(?).

After the initial misting I didn't bother again; I'd been working under the assumption (rightly or wrongly) that the humid atmosphere of the bag would suffice.

The small amount of surplus that I left as patties in the dry air is pretty crumbly.

Thanks again; as long as the steps that I'm following are generally ok, then that'll be ok to get me going.

Sean,
The surplus would have had to be misted frequently to be viable.
and thank you David for your informative post, especially a good reminder for those who haven't been doing this for very long or who have been taking a break.
Happy casting,
dena

65-70 is good temps.
If you keep the piece damp for 7 days you should be good to go.

Let us know how that recipe works out. It is interesting because it contains no large aggregate. It is akin to a hypertufa mortar.

7 days at 65F-70F should give you the 75% of your cure, the rest coming mostly over 2-3 more weeks. If it isn't pretty well set up now then it might never be strong enough. Curing doesn't need extra water, there is already enough in the initial mix, you just have stop it evaporating.

Hi s'n'b,

hypertufa mortar, eh? It's funny that you should say that; I had a look at the piece only a few minutes before reading your post, and I'd been thinking, 'boy, this looks a lot like mortar'; that or sandstone, perhaps. I left it a week in a large plastic bag, then removed it; it seems quite sound.

I took the recipe from a web page; the chief attraction was the use of a styrofoam core. The styrofoam was painted with carpenter's glue before adding the mix. I followed those instructions pretty closely, except for the curing, which wasn't mentioned at all. In fact, here's a cut and paste from the article:
"Leave the whole to dry for a minimum of 24 hours before planting - longer if you have the patience (but then what gardener does?)". Other than that the article was reasonably comprehensive, and I'm certainly grateful to the fellow for sharing the fruits of his experiences with this. I'll try and pop that in below.

Would an aggregate be desirable? I've started looking for cryogenic perlite (here in Vancouver, Canada); I asked at a couple of places, but no luck so far.

cheers,

Sean

Here is a link that might be useful: trough on styrofoam

Large aggregate can make your concrete stronger.

Traditional concretes consist of a large aggregate of rock chippings, enough small aggregate to just fill the gaps between the rock chips, and then just enough cement to bind it all together. The result is nearly as strong as the rock chips themselves. Cement is extremely strong when used to span the tiny gaps between the aggregates and the aggregate takes most of the load. Any microscopic cracks in the cement cannot spread because of the large aggregate.

In a mortar, there is only sand and cement. The higher proportion of cement means that it is harder to get a uniform cure without some cracking, and more of the load is taken by the cement. Cracks can spread more easily and mortar tends to be more brittle than concrete. But regular portland cement mortar is very stiff because the sand is inflexible and is fixed into place by the cement.

Lightweight concretes use an aggregate which may be weaker than the cement itself. Strength depends very much on uniform mixing and curing. Careful curing can produce a strong cement and the aggregate can still prevent cracking. The results can be stronger than a regular mortar when made properly. Or not. If high strength is needed you might want to include some fibres to prevent cracking under load, or work on a supporting mesh or rebar.

Hypertufa recipes vary a lot but the basic rule is that it will be weaker than the equivalent without the peat. Peat has no strength. Peat provides no rigidity and no resistance to cracking. Particularly, any lumps in the peat will make for very weak spots. A good hypertufa mix, with only fine peat particles and a suitable additive to span the resulting small holes, can still be quite strong. Fibres are useful, but other large aggregates like vermiculite can also be useful. Sand will add a lot of strength to hypertufa but also adds a lot of weight.

Morning,Sean.
For cryogenic perlite,go to Pacific Western Systems Supply.They have several locations,but,if you're in Vancouver,the one I would use is on Boundary near Broadway.Their number is 604-293-1741.
If that fails,e-me.I have stuff that doesn't figure in my future needs at present,so I'll sell you a bag.I'll be in town in a couple of weeks(I live in Garden Bay on the Sunshine Coast)and can arrange to get it to ya then.
Cheers from here

Sean
There are also two types of Perlite that are more common and almost identical to Cryogenic. Fine like sugar.
Both are used as concrete additives in concrete. I have forgotten there names. They are simply numbered.
According to Grace Industries who makes the stuff they are technically superior to Cryogenic for use in concrete.
I had a bag of one of these types and found it to be much more dusty than Cryogenic and nasty to use. I prefer Cryogenic.
So when asking about Perlite ask about the fine grades designed for concrete. They might be easier to find.
I personally stocked up. I bought ten bags this winter. That's a lot of Perlite but my supplier only brings the stuff in once a year.:)

David,
Sounds like you really like the perlite. In making concrete items from molds would it work well by mixing it with portland and sand? Would it be pretty strong?? Also, would I have less air bubbles if I used a cement mix rather than a sand mix ??
Thanks very much.

Rhonda-I'm a big user of molds.Although I've veered away from using it,I did do a number of pieces using perlite in its very fine state.With vibration,my pieces came out of the molds looking just fine.Many have now spent a rather wet winter fully exposed to the elements and there is zero trouble with these pieces.If it's the direction you want to go,good on you,mate!!
I'm not a coarse agg user,never really have been,so the fine perlite(along with 130 or so mesh sand)have given me nice details.Course,when I put in the waterfall this summer,I'll be looking for opinions abour gravel and such.
My main thrust now,an area that I want to continue to boldly explore where few have gone before(theme from "Star Trek",please)is thin,lightweight concrete creations.So far,I'm having a lot of fun with my new formulae,and I'll continue to push the envelope(theme from "A Few Good Men" inserted here!)until I'm satisfied.
Live long and prosper on,dudes and dudettes!!
Cheers from here

The yellow stand ring under this ball is 100% cryogenic perlite no sand and it is strong.

{{gwi:66773}}

This green shell is also 100% perlite. It was the liner for an osyter shell pot. Osyter shell concrete is like a sieve so the black osyter shell concrete was added to the outside of the waterproof green shell later. It was very nice when done. It's smooth and very lite weight.

{{gwi:65884}}

This pink ball was my first cryogenic perlite project the aggregate is 80% perlite and 20% very fine white sand. Very strong.

{{gwi:66066}}

IMO Perlite makes an excellent sand substitute but it takes almost twice as much perlite dry as sand because it compresses and packs. I use an acrylic admix or latex paint but only at about 25% of my water.

Cryogenic perlite carves like a dream even completely cured. It is great stuff.

Thanks David I appreciate it very much and the pics too. :)

Glad to help Rhonda.
There is another cool thing about Cryogenic Perlite concrete I didn't mention and it's a biggie.
Even a receipe with 50% sand 50% perlite is very easy to mix.
It is like smushing mashed potatoes and easy on the hands, your back, and your gloves.
It is light and almost fluffy in texture. I can make batch after batch without hand fatigue.

Sounds great!! Some of my molds are pretty small and pretty detailed (faces and masks) would this work for that. It sounds like it needs to be pretty dry. I'm wanting to lighten them up. How are the air bubbles?? Should I stick with a concrete mix?? My goal is to get some things made and put them on consignment.

Hi,

thanks for write-up s'n'b, and for all the other input. It was hypertufa troughs that brought me here originally, but the possibilities seem to mushroom right out. Cement and concrete; who have thunk?

And Rick I already have to thank for an earlier post post mentioning Pacific Western Systems Supply. I nipped by there after work today and picked up a couple of bags. Thanks all the same for your kind offer. So at this point my research efforts are starting to outstrip what I've actually been doing. Time to get my hands dirty I think.

Marvellous; thanks again,

Sean

Hi Rhonda
I don't use fine molds. All my work is hand cast for shape only and then finished with brushes and other tools.
I'm never trying for a super smooth finish and I do use a very dry mix to keep maximum strength. But you can get a glassy smooth surface with a runnier mix or a trowel..
Perlite mixes do some odd things. You would expect them to get dryer as the dry perlite sucks up moisture but they don't. They tend to get runnier as time goes on so you have to be very careful adding water. Like a superplaticizer mix it can become liquid in a hurry. As for bug holes, I don't get those in my mixes but I do get small flat surface imperfections that are easily removed with a brush. I can't explain them. I suspect they are caused by my home made release oils.
That said you can't go wrong by trying this Perlite. It's cheap and if it does work out it works great in the garden as a soil lightener.:)

Last year I made a test bowl from pea gravel and cryogenic perlite. This puppy was made for the purpose of seeing if being full of ice and snow would destroy it. It's perfect!
It was frozen and thawed at least 20 times this winter and there is not a mark on it. This is zone 3.
I'm very impressed. I doubt a box shape or straight sided trough would have made it but I'm happy.
I didn't expect a recipe of 50% stone and 50% perlite to stay
together. I was sure the stones and perlite would expand at different rates.
I'll post a picture of this bowl as soon as I get my camera back. It's not fancy but it's ALIVE!

{{gwi:66774}}

{{gwi:66775}}

The band you see around the middle in the third picture is 80% perlite/20% silica sand concrete made using latex paint as an admix and it goes right through and all way around the bowl.
This bowl was made as a test critter and not to be fancy. I'm surprised it survived the winter. It was a strong mix Portland 1 part to 3 parts aggregate.

{{gwi:66776}}

Thanks for the information all and thanks David for the pictures.I love your bowl with colors.
Bands of different textures and colors is a really neat idea. It really looks interesting.
Debbie

Awesome pictures and feedback about the finer perlite.

David, I'd like to ask, for the record, when you say 80% perlite/20% silica sand and "a strong mix Portland 1 part to 3 parts aggregate", is the aggregate referred to the mix of 80% perlite/20% silica sand?

I also can't help but wonder about the orange piece to the left. What's the story with that? Or perhaps I've missed it whilst reading through.

And, hey, one more. Some of your other perlite posts mention admix, any comment on that?

Lots of questions ; )

I'm planning on slapping some kind of perlite lightened mixture onto some 3/4" styrofoam sheet this evening. See how that goes. I've had a hankering ever since I saw those Hawaiian vacation wall photos.

Cheers,

Sean

Thanks daybees.
These are actually the ugly ones, experiments I kept and used for winter testing.
I've sold some really nice ones. I'll try to post pictures of a few nicer one's I'm working on now. I'm doing Bonsai pots right in various shapes and sizes. I think they may be good sellers. My friend wants a Bonzai slab as well so I'm trying to figure out the best way to make one that looks natural.

Hi Straw Dog.
A 80% 20% mix would be 8 parts Perlite 2 parts sand mixed together.
Then that is mixed with Portland at 3 parts mixed aggregate to one part Portland. Does that make sense?

The orange piece is just pea gravel and white sand bowl colored god awful orange. I hated the color so the piece spent the winter under a dripping roof eave. The darn thing survived covered with ice! I may just keep it around now.

Admix for me is a very uncontrolled. I use Elmers glue and latex paint in some stuff. In my good pieces I use a high quality acrylic admix. Glue, latex paint or REAL admix makes a big difference even at additions as little as 20% of your water. I recommend throwing admix into every piece you make. You can buy gallon cans of latex paint at flea markets for a buck a can.

Ok; yes, makes sense.

I just mixed up 2.6 liters of this; couldn't wait. Perhaps I could have put less water in; it was like mashed potato.

btw, that orange doesn't look too bad from here,

over and out,

Sean

Rick
Here's some ideas for concrete waterfalls that I came across.
Debbie

Here is a link that might be useful: decorative concrete net

Somehow this thread on curing got sidetracked by cyro perlite??
I would like to get it back on track for proper curing.

Lets get suggestions on all the details of curing a piece for planting.
How many days from creation to planting.
Best how to leach out the lime so the plants wont die.

I made my piece and after 5 days in a wet bag with added water once or twice I am soaking in a tub of water vor 3 days changing the water every day and then what do I do to prepare for planting?? I assume just let it dry for and day or two and plant???