DIY rock

[BCOrchidGuy]

I'm going to be makeing some of my own aragocrete rock, I've actually done some but I keep running into a problem and I'm wondering if anyone else has had the issue.
I'll make the mix up, 1 part white concrete 5 parts aragonite gravel, then I'll add just enough water to make it wet, not sloppy. I'll spoon the mixture out onto a bed of aragonite gravel, then fill any areas I want to keep hollow and then top it with more of the mixture, then cover the works in aragonite gravel. I'll wait 24-36 hours before I remove the peice but it always breaks, it's always still damp. I'm using a foam box as suggested by Garf. Just wondering if anyone has a better idea?
How about curing, anyone try muriatic acid in water for a couple days then fresh water? I know folks have done vinegar.

Doug

[apepper]

You may want to add sand to that mix as well, the gravel may be too coarse all on its own. You could also try adding some reinforcement such as pvc pipe if the pieces are thin and branching or eggcrate cut to size.

You may have already seen this site but it describes a concrete mix for diy rock. 8 parts concrete, 13.5 parts sand, 11 parts gravel and 10 parts plastic shavings (light reinforcement)

http://www.mindspear.com/reef/concrete/

[StirCrazy]

what gravel are you using? and how wet are you getting it? if you are only getting it wet enuf to look like wet sand then thats not enuf water and the cement won't activate properly. you need to get it a little sloppy. I am going to be playing around with some pretty soon also, I am going to use 1 part type III portland cement, 5 parts sugar sand and one part crushed coral.

Steve

[BCOrchidGuy]

Steve, I'm using Natures Ocean Premium special aragonite gravel. I mixed it up so it would do the mud test, enough water to hold together.
My issue is that it just doesn't dry out, it stays damp the whole time it's in the box. I'm thinking I'll try it out on a open peice of plywood and maybe put a fan blowing over it to try to dry it out better.

Doug

[StirCrazy]

try leaving it in for 2 or 3 days to set up some more and see what happens.

Steve

[BCOrchidGuy]

Guess I'll have to try that, it just occured to me the videos of them doing it at Garf are all done in the bright sunlight looks like summer. I assume the heat outside helps.. aren't they in the Mid West?? probably not alot of humidity to deal with either.

Doug

[Tau2301]

Cure the concrete slowly as it makes a stronger structure. All the articles have read on curing concrete states that a slower process is the best.

When I made my pieces I left them in the mould for 24 hours. Then I would extract them from the form material (damp crushed oyster shells), but leave them in side the form enclosure (big plastic box) with the damp shells for another 24 hours.

I would then leave the pieces dry inside the garage (out of any direct sunlight) for couple of days more. After that I would begin the water curing process.

[BCOrchidGuy]

Kim thanks, I've been leaving the peices in for 24 hours but they are still damp and crumbly when I pull them out. I'm thinking that I'll just put in 100 pounds of base rock and 50ish pounds of live rock.

Doug