The Ultimate DIY Rocks! - Page 2

Travis L. Stevens · #26 03/24/2006, 02:03 PM

I'm not curing it by cooking it. I'm drying it by cooking it.

The curing process is a good 4-6 weeks in water. So far, it's structural strength has been quite sound. It took a lot of work just to break that hunk of rock in half

Qwiv · #27 03/24/2006, 02:12 PM

Why are you drying it, just leave it outside. You mentioned that it takes a long time to dry, this is because you are evaporating the water inside the concrete. The concrete uses this water to hydrate.

I know a lot about concrete, I work with it every day. Baking it can lead to crazing, dusting and all types of problems. I typically use concrete in a structutal way, but it also applies here.

If you are getting great strength now/density, you could do better if you cured it right. The best way to do it would be to set it outside and mist it for a few hours. Then throw it in a tub of water.

Why did you stop using the oyster shells, I liked the texture it produced.

Travis L. Stevens · #28 03/24/2006, 02:19 PM

Leaving it outside and misting isn't an option for me since I live in an apartment, and with two little kids, leaving it still wet inside is also not an option. Messy kids...

So, just baking it solved the problem. Instead of taking 24 hours, two works for me. If you have the chance of not cooking it, go for it. But I don't. I doubt in the future that I will leave 100 lbs of wet rock lying around the apartment for 24 hours either since it seems to work fine for me

I stopped using the oyster shells because it looks too "unnatural" for my taste. And it is really sharp. When taking out a 10lb piece of rock afer having your hands in the tank for an extended amount of time makes it really easy to cut your skin. The Salt/Cement is very smoot, on the outside of course.

hmott · #29 03/24/2006, 02:51 PM

Quote:

Originally posted by Qwiv
I am sorry, I love the thread but baking the rocks is a bad idea. Concrete does not cure by drying, it gets hard by a proccess called hydration. It is actually using the water as fuel in the chemical reaction to get hard. The strongest concrete is cured in water. Backing the mix is only making it weaker. If you are looking to speed up the cure time, you want to use an accelerator in the concrete, not bake it.

Other than that, good work man.

will an accelerator still leave the rock "reef safe"? What accelerator should be used or won't it matter?

tekknoschtev · #30 03/24/2006, 03:14 PM

Quote:

Originally posted by Travis L. Stevens
tekknoschtev - Did the Sand and Cement stick together well? Thanks for sharing your experiences.

The sand + concrete + rock salt (I used the driveway ice melting stuff, works great, but I've only used solid rock salt, not the calcium chloride or Mag Flake stuff) works great and provides very light rocks. I'll get a picture in a week or so when I'm home with my batch that has been curing for a while. The sand gives the outside a nice natural texture. The sand I used is a mixed grain size from dust to 3-5mm. Nothing huge, but the variances in the grain size allow for some cool textures.

Quote:

Originally posted by Travis L. Stevens
Leaving it outside and misting isn't an option for me since I live in an apartment, and with two little kids, leaving it still wet inside is also not an option. Messy kids... So, just baking it solved the problem. Instead of taking 24 hours, two works for me. If you have the chance of not cooking it, go for it. But I don't. I doubt in the future that I will leave 100 lbs of wet rock lying around the apartment for 24 hours either since it seems to work fine for me

As long as it works. I found that with my first mixture with more concrete to sand ratio that it hardened in my sand molds over night, but with the less concrete per volume it took longer in the mold to cure. We kept the sand damp to make the molds, but after that the slow evaporation did the trick. Two weeks later we have some pretty strong rocks. The best part of doing it this way is that we did it in rubbermaid tubs so the lids could be put on and they could be stored out of sight for a while. But if baking them did the trick for you (and by the appearances of it, it did) thats great. I molded it in the sand to get some intricate shapes and caves, and overhangs, etc.

Qwiv · #31 03/24/2006, 03:50 PM

Quote:

Originally posted by hmott
will an accelerator still leave the rock "reef safe"? What accelerator should be used or won't it matter?

There are so many accelerators on the market, that you would need to read the MSDS on them. The only problem with using an accelerator is aquiring it and getting it mixed correctly. This would be a tough task my hand. Quickctete at HD had a pretty fast cure time as is, so for a DIY job, should work fine.

As to putting the concrete in the oven, if it works for you, that is fine. For others following the thread, don't do it unless you have a strong reason too. The concrete would have be hard enough to handle in 4 hours and putting it in the oven only makes it weaker.

http://www.popularmechanics.com/home...s/1275111.html

Another experiment people following this thread can try is to make you rock and a few hours later dig into it with something hard to get a more unique shape. Then after a little wait, spray the rock with a preasure washer. This should clean the smooth concrete off the surface and expose the arrgagate below. This is how you pour the concrete you see that shows the pebbles inside of it, common on walk ways. It is called exposed aggregate concrete.

M.Doshier · #32 05/08/2006, 03:18 PM

I was wondering, after you make your mold and its sitting to dry, what if you threw some salt on it to make little indentions. Also, if this rock is so light and stuff, would any of it ever crush under the weight of other rock on top of it?

M.Doshier · #33 05/08/2006, 03:18 PM

I was wondering, after you make your mold and its sitting to dry, what if you threw some salt on it to make little indentions. Also, if this rock is so light and stuff, would any of it ever crush under the weight of other rock on top of it?

Travis L. Stevens · #34 05/08/2006, 03:30 PM

So far, weight of other rock doesn't seem to effect it. This isn't testing it with very much. Maybe I should go home and stand on one. I'll let you know if it fails. Afterall, I weigh 250lbs and if only one rock can hold up that weight, then a large pile of rocks should be fine. But that is a great question.

As far as the indentions on the outside goes, I've thought about either molding my rocks in a bucket of rock salt similarly like you would with a bucket of sand. This way, you can wash of the rock salt incasement unlike sand molded DIY rock where it sticks to the outside. Also, the outside of the rock is already rather "bumpy" as it is. But I guess it's more of a personal preference.

afelder · #35 05/10/2006, 01:56 PM

How many shapes have you tried. I have the GARF style rock and have made all sorts of shapes. Plastic shopping bags make a great interior to artificial tonga style rock. You just mold around it and it holds branching shapes well.

Travis L. Stevens · #36 05/10/2006, 02:02 PM

Truthfully, I haven't tried to make very many shapes, I just wanted to make sure that it worked first. It has the same consistancy as any other DIY Rock, so I would venture to guess that you can make it into any shape that you want.

itstheantitang · #37 05/10/2006, 09:01 PM

I ended up making some, and the problem is a few pieces float. Even some of the big pieces float. This confuses me, because it would seem the cement would be less dense with the water.

FWIW, the rocks have been curing for 1 month now.

Stonepost · #38 05/10/2006, 09:07 PM

Anyone thought of using PVC tubing for holes / crevices? wouldn't be to hard to mold around it and could make diffrent sizes fairly inexpencive.

exoticaquatix · #39 05/10/2006, 09:34 PM

Quote:

Originally posted by itstheantitang
I ended up making some, and the problem is a few pieces float. Even some of the big pieces float. This confuses me, because it would seem the cement would be less dense with the water.

FWIW, the rocks have been curing for 1 month now.

the reason your rocks floats is beause the total density of your rock is less than water. basicly you have enough air trapped in the rock to make it float. have you ever seen pumice? sometimes you get little pieces in the pockets of new jeans. its volcanic and as it cools enough air is trapped to allow it to float. same thing.
-nick

Travis L. Stevens · #40 05/11/2006, 08:19 AM

Quote:

Originally posted by itstheantitang
I ended up making some, and the problem is a few pieces float. Even some of the big pieces float. This confuses me, because it would seem the cement would be less dense with the water.

FWIW, the rocks have been curing for 1 month now.

VERY interesting. None of my rocks have ever done it. Was your mixture straight salt/cement? Or did you put some PVC in the middle or some sort of plastic as well?

WIJAONKA · #41 05/11/2006, 07:08 PM

Okay, The rocks look GREAT!!

I live in Las Vegas where the popular type of Portland Cement is Type V.

My question is this:

Does the cement 'type' make any difference in creating rocks? I understand that it needs to be 'portland', but does it have to be type I??

Thanks,

W

NCreefwannabe · #42 05/11/2006, 10:48 PM

what about using say crushed coral to give more texture? Its fairly cheap compared to sand. You could also make rigs of say pvc rods or small pipes or such and mold around those. Then pull them out to create porous rocks, caves and holes.

ReeferMac · #43 05/12/2006, 05:17 AM

The Type does matter.... Gosh, forget where I read that, but.... the different types each have different curing materials, or rates, or... there's something about the type's out there (obviously). I don't know as it was anything that would affect your rock, however. There was some discussion way back when about different curing agents you could get, and some names of chemicals were tossed around (from folks in the Cement business, not me), but I can't even come close to remembering the particulars. Perhaps the search engine can tease it out?

- Mac

Travis L. Stevens · #44 05/12/2006, 08:43 AM

Quote:

Originally posted by NCreefwannabe
what about using say crushed coral to give more texture? Its fairly cheap compared to sand. You could also make rigs of say pvc rods or small pipes or such and mold around those. Then pull them out to create porous rocks, caves and holes.

That defeats the whole purpose of using the rock salt. Crushed Coral is solid, dense, and doesn't dissolve. There will be very little porosity after it's done curing. You can do the different methods of pipe, and such to create caves and overhangs in any formula of DIY Rock.

For a reference point, if you go back to the First (or second, I can't remember) Batch where I used just Crushed Oyster Shell, a cheap alternative to Crushed Coral, and then look at the Third batch where I used Rock Salt, you can see a dramatic difference in porosity. The importance of the porosity isn't for looks. It's to help harbor more Denitrifying Bacteria to make it actually work like real live rock.

WIJAONKA · #45 05/12/2006, 07:14 PM

Quote:

Originally posted by Travis L. Stevens
The importance of the porosity isn't for looks. It's to help harbor more Denitrifying Bacteria to make it actually work like real live rock.

This is very true. HOWEVER, The Third Batch looks fantastic!

Thanks for the info regarding cement types. I will have to do some more research.

W

ReeferMac · #46 05/12/2006, 07:34 PM

There was some type of additive you could put into the cement mix (or, buy type "___" Portland Cement, which already had it in there), to add stability in marine environments. But it really didn't matter to the end result all that much, IIRC (which is hopeful at best), because properly cured, the arragocrete should be equally inert, regardless of wether you used that fancy additive or not. I think it was some guy talking about marine grade cement used for pilings, and that sorta thing (might find it, or info about it, at a boat shop, if you happen to live near the coast). There was something they put in that type of cement, that changed the type #, and made it 'better' for marine environments.. but again, once cured, was moot.

Sorry, best me feeble mind can do at this level of inebriation.

- Mac

Travis L. Stevens · #47 05/15/2006, 08:41 AM

If anyone actually finds a link to it, either PM me or post it on thise thread. I would really like to read it and it would be good reference for anyone else reading this thread.

itstheantitang · #48 05/15/2006, 08:49 PM

Quote:

Originally posted by Travis L. Stevens
VERY interesting. None of my rocks have ever done it. Was your mixture straight salt/cement? Or did you put some PVC in the middle or some sort of plastic as well?

It was just straight salt/cement, 4 to 1 salt to cement.

I have shaken rocks out and there is no air trapped inside.

Anyway, I think in about a week they will be done (need to test pH), and I will either skewer them on some PVC or put them in mixed in with some LR. They are not very buoyant, enough to float them.

As time goes on, the rocks sink more. Hmmm. I can only hope the higher density of saltwater doesn't affect the situation.

humboldt reefer · #49 05/15/2006, 09:06 PM

How large is the grain size of the salt your using? You could have a bunch of hollow pockets in the rock that's causing it to float. I made some yesterday and some today. I havent put yesterdays in the water yet. hope they dont float. the average size of the salt I used was probably 3/16 - 1/4"

Travis L. Stevens · #50 05/16/2006, 08:02 AM

Quote:

Originally posted by itstheantitang
It was just straight salt/cement, 4 to 1 salt to cement.

I have shaken rocks out and there is no air trapped inside.

Anyway, I think in about a week they will be done (need to test pH), and I will either skewer them on some PVC or put them in mixed in with some LR. They are not very buoyant, enough to float them.

As time goes on, the rocks sink more. Hmmm. I can only hope the higher density of saltwater doesn't affect the situation.

That's very interesting. Sorry about your plight. But it is kinda cool. Care to share pictures with us?