The Ultimate DIY Rocks!

[TekCat]

I've seen the question about baking soda in the mix before, but probably missed the answer.

To my knowledge, baking soda is quite difficult to dissolve in water. Wont it be better to have it in the mix to create very tiny pores instead of solar salt? Please pardon my ignorance on the masonary subject, I am still learning

 

[eshook]

Yes let the sun do your work and save electricity. I actually conducted an experiment with a simple solar oven for curing rocks. For reference:

http://solarcooking.wikia.com/wiki/Minimum_Solar_Box_Cooker

I built a simple solar cooker using 2 small boxes, aluminum foil, and an oven bag for the plastic. I placed a meat thermometer in the oven and periodically checked the temperature. It got up to 120* very quickly. I think with this simple device I could reach 150* with the proper configuration. Obviously my design was small scale and would only work for 1-2 rocks at a time, but your larger scale version painted black might work well.

 

[Insane Reefer]

<a href=showthread.php?s=&postid=10560415#post10560415 target=_blank>Originally posted</a> by mosthated00
would mixing in baking soda when making the rock help with the kuring process? anyone tried it?

Sorry, Mosthated - we weren't ignoring you, just forgot it needed to be answered, lol.
A few of us tried it on rock that we were kuring, but I'm not really sure what the consensus on it was. pH of the water always seemed to hang out in the 9 range. I can't say I noticed any real difference. As far as adding it into the mix, well, I don't think anyone has tried it yet. Here is a pdf that has a formula for the addition of SB, to precipitate lime, but I don't think any of us have the mathematical or cement chemistry knowledge to actually use the formula
Too much will ruin the slurry, not enough probably won't have an effect...
http://www.miswaco.com/Products_and...llingProductsDocuments/SODIUM BICARBONITE.pdf

and do you have to change the water that the rock is in for it to kure? i mean i have been doing water changes on the rock i made for about 5 weeks and the ph is still through the roof. but i was wondering would the mix still kure if left in the same water?

The only way to avoid water changes would to be either to place it in a clean, free flowing water way, OR to add something to the water itself to buffer the pH and allow more stuff to go into solution. Even with air kuring, there is still a need for some water changes, but they are greatly reduced - usually in the week to two week range.

Welcome to the thread, Southgate!

And Kevin. I know you asked this of Cayars, but since it ties in loosely with the other questions I just tried answering, I will also add this to my reply.

...it seems to me that there is no advantage to adding anything to speed up the process and just kure for 28 days, right (other than our own impatience)? Or is there?

You are correct. For most people, who aren't on a schedule, and aren't impatient, there really isn't a reason to veer from the beaten path on this one - except to forget the "traditional" water bath start after day 3-7; rock should really just be left alone for at least two weeks, and I would urge people to extend that to 4 weeks. The only thing about the air kuring is that it does seem to be a bit harder to get the salt out of fully cured rock - but not so much so that I would try to remove the salt or start a bath before 2-4 weeks...

 

[Insane Reefer]

<a href=showthread.php?s=&postid=10567185#post10567185 target=_blank>Originally posted</a> by TekCat

To my knowledge, baking soda is quite difficult to dissolve in water. Wont it be better to have it in the mix to create very tiny pores instead of solar salt? Please pardon my ignorance on the masonary subject, I am still learning

Welocme to the thread, Tekcat!
Even the actual cement experts will admit that they are still learning, lol - cement is still not completely understood, and research on the subject leads to new discoveries everyday it seems - and things that the experts accepted as truths are sometimes being overturned with new research...
That being said

SB isn't so difficult to dissolve in water - there might be a slight residue left, but most of it dissolves pretty readily.
Adding SB into the mix for the purpose you propose just doesn't work. Even Alka-Seltzer doesn't work - it dissolves too quickly to produce any results.

 

[Neptune777]

<a href=showthread.php?s=&postid=10566965#post10566965 target=_blank>Originally posted</a> by Insane Reefer
If that is all you want to accomplish, just putting it in plastic outside in the sun will do that.

Not in the middle of January on a cold night

 

[Neptune777]

<a href=showthread.php?s=&postid=10567085#post10567085 target=_blank>Originally posted</a> by Insane Reefer
Oh, if you do the rock sauna, you can add the co2 while doing the moisture - I think the humidity should allow the co2 to penetrate the rock better, to get that carbonated layer...

LOL, Az.

CO2 + Water = Acid I don't think this is what we want during the hydration process.

 

[mr.wilson]

I don't know how the reaction would work either, but baking soda will add carbon and speed the curing process in a similar fashion to the Co2 gas method. I would use sodium carbonate, rather than sodium bicarbonate though.

The garbage can method looks fine to me. I would add an air diffuser to help with evaporation/humidity. Once the lid is on, that sucker is going to get hot and very wet, but it won't generate steam. I don't know how significant this is to the cure time or quality of the cement.

An aquarium heater will heat the water more efficiently than the burners mentioned. The heaters thermostat goes to 90F, but the actual element gets much hotter than that to achieve this.

 

[Neptune777]

<a href=showthread.php?s=&postid=10567609#post10567609 target=_blank>Originally posted</a> by mr.wilson
I don't know how the reaction would work either, but baking soda will add carbon and speed the curing process in a similar fashion to the Co2 gas method. I would use sodium carbonate, rather than sodium bicarbonate though.

The garbage can method looks fine to me. I would add an air diffuser to help with evaporation/humidity. Once the lid is on, that sucker is going to get hot and very wet, but it won't generate steam. I don't know how significant this is to the cure time or quality of the cement.

An aquarium heater will heat the water more efficiently than the burners mentioned. The heaters thermostat goes to 90F, but the actual element gets much hotter than that to achieve this.

My idea behind this is to have constant hot moist air to assist or promote the hydration process. Cement needs to have moisture present at all times to hydrate properly....and as you know this is what ultimately drives the pH down. This is why wet burlap and other methods are used for structural cement projects....to keep the hydration process moving (although for strenght not pH drop).

This sauna would keep the rocks warm and humid 24/7 during the cure....keeping it going constantly/consistantly. This is my thought process at least...

 

[Insane Reefer]

<a href=showthread.php?s=&postid=10567602#post10567602 target=_blank>Originally posted</a> by Neptune777
CO2 + Water = Acid I don't think this is what we want during the hydration process.

I'm saying add it in as a gas, not into the water, but into the upper chamber - this is what we want...

Plus, in one of my emails from Nick, he suggested "fizzy water" as it will create the carbonated surface we want, and he says that it won't create a very harsh reaction.

Basically, if I understand what he is saying, acids in general leave a alkaline surface - since alk isn't too big of a deal, we could use it, but he says he has never heard of cement being cured with acid.
I will quote the relevant bits from the email:

Even when fully hydrated (most concrete never quite fully hydrates - it
depends on the water-cement ratio) the concrete will still be very
alkaline. However, you can have an alkaline interior and a carbonated
surface. If the cement paste is fairly dense, this could act as an
effective barrier. NB: not the difference between dense paste and
porous concrete - you can have both. I mean the cement paste component
is dense but the concrete could still be highly porous if eg: you have
a uni-size aggregate and a low ratio of cement to aggregate.

Microsilica will reduce the alkalinity. Again, there are large pores -
of the order of a millimetre or more - these would contain air when the
concrete is mixed, and there are capillary pores measured in microns.
The microsilica will tend to fill the capillary pores by reacting with
the calcium hydroxide from cement hydration to make more calcium
silicate hydrate. Again, you can have dense paste, eg: with microsilica
but still have porous concrete. I suspect your bugs will want big holes
- you can have this and still fill the little holes with microsilica.
--------------------------------
The alkali in concrete comes partly from calcium hydroxide - a major
component of hydrated cement - but also from sodium and potassium
hydroxide. These have a higher pH than calcium hydroxide. They tend not
to bind with the hydrates (but can with microsilica, hence the lower
pH) and can be fairly easily leached out, which is probably good.
----------------------------------
a) instead of using vinegar, try using fizzy water. Carbonated water
contains carbonic acid; that will reduce the alkalinity a bit and also
provide some carbonate to help make a thicker carbonated layer at the
concrete surface.

b) How about substituting lime for some of the cement? Lime has a lower
pH than cement (no sodium or potassium hydroxide). Make sure it is
slaked lime - calcium hydroxide. Don't use quicklime - calcium oxide.
Or use a strongly hydraulic lime, ("eminently hydraulic" in European
terminology) as used traditionally for masonry if you can get it. If
not, a blend of 10% or 20% white cement and the rest as lime should be
OK. Obviously, lime is caustic too so take the same precautions as for
cement.

With lime, you should get a purer rock in the sense of a higher calcium
carbonate content compared with cement. It won't be as strong and it
may take longer to set and harden but the final product should be
better, provided it is strong enough. There will be less aluminium as
well. If you use limestone aggregate, you will have a product that is
maybe 90% limestone by the time it has all carbonated. Again, I would
try this mix with a uni-size aggregate to get the pore structure.

 

[Insane Reefer]

<a href=showthread.php?s=&postid=10567570#post10567570 target=_blank>Originally posted</a> by Neptune777
Not in the middle of January on a cold night

True, but I don't think a tank heater is going to do much on a cold january night either, except keep the water from freezing

And they don't call it "humidity curing", they call it "steam curing" - I think that by now, the industry would know which works best for curing rock (and I'm not trying to be snarky here). Granted, humidity is used in 3rd world countries to hasten curing, as well as on construction sites the world over, but steam is the key for one day hydration with traditional portland...

Using the grill element isn't as efficient in the long term, I agree, however, if I can accomplish in one day (proven in an oven) what it might take Neptune 7 days (and we are just guessing here at this point) to do with a tank heater, then I think that my way will be as efficient for the short term...

 

[badfish03]

<a href=showthread.php?s=&postid=10567570#post10567570 target=_blank>Originally posted</a> by Neptune777
Not in the middle of January on a cold night

That would be a good time to wrap your trashcan in a water heater insulation sleeve to help keep the warmth in. Another rule of thumb is not to work with wet concrete when the temps are 40F and dropping.

Robert

 

[Neptune777]

<a href=showthread.php?s=&postid=10567868#post10567868 target=_blank>Originally posted</a> by Insane Reefer
True, but I don't think a tank heater is going to do much on a cold january night either, except keep the water from freezing

And they don't call it "humidity curing", they call it "steam curing" - I think that by now, the industry would know which works best for curing rock (and I'm not trying to be snarky here). Granted, humidity is used in 3rd world countries to hasten curing, as well as on construction sites the world over, but steam is the key for one day hydration with traditional portland...

Using the grill element isn't as efficient in the long term, I agree, however, if I can accomplish in one day (proven in an oven) what it might take Neptune 7 days (and we are just guessing here at this point) to do with a tank heater, then I think that my way will be as efficient for the short term...

I think you have missed my point. I am not doing this for a one day cure......I never said they call it "humidity" curing......water is needed to keep the hydration process going and this is a good way for me to provide stability during cure....with nice warm super saturated air. I can wait one week from production to tank (sure beats 4-6 weeks) with very little cost involved.

Trust me....an aquarium heater in 5" of water will keep it plenty warm.....I know.

 

[Neptune777]

<a href=showthread.php?s=&postid=10567787#post10567787 target=_blank>Originally posted</a> by Insane Reefer
I'm saying add it in as a gas, not into the water, but into the upper chamber - this is what we want...

Plus, in one of my emails from Nick, he suggested "fizzy water" as it will create the carbonated surface we want, and he says that it won't create a very harsh reaction.

Basically, if I understand what he is saying, acids in general leave a alkaline surface - since alk isn't too big of a deal, we could use it, but he says he has never heard of cement being cured with acid.
I will quote the relevant bits from the email:

I know what you were saying.....in the upper chamber. It doesn't matter...if the cement is moist it will create acids when in contact with CO2.....as well as any consensation dripping.

I don't follow your acids=alk surface..... Acids + alk surface (fresh cement)= neutral not well hydrated cement.

The suggestion from Mr. Collins was to add dry rock into a CO2 chamber.

 

[Neptune777]

<a href=showthread.php?s=&postid=10568241#post10568241 target=_blank>Originally posted</a> by badfish03
That would be a good time to wrap your trashcan in a water heater insulation sleeve to help keep the warmth in. Another rule of thumb is not to work with wet concrete when the temps are 40F and dropping.

Robert

Both true......but adding Calcium Chloride allows you to work in lower temps as well.

 

[Insane Reefer]

Oh, I understand you aren't going for a one day cure - I kind of mixed two replies - perhaps I should have addressed that part to Mr Wilson, about the efficiency thing.

And I know your didn't call it humidity curing, but in essence, that is what you are doing. By warming your water to 100°, you are creating a humid environment, hence my calling it "humidity curing" - at 100° your aren't going to create any steam ("steam curing", but I am sure you knew that), but the humidity will help provide a better cure, for sure.

Will it lower the pH? Not sure, but my experiences with baking lead me to believe that you may see a slight lowering of pH within that week period (or after baking), but it isn't going to go away that quickly. If hydration has ceased (mostly anyway), reducing the pH becomes easier and quicker as you are flushing away less of the rock itself (solution only holds so much), and mainly getting the hydrates Nick mentioned in that email, out. His email also makes it more clear to me why longer air curing brings the pH down...

Keeping the rock moist/humid during hydration is a given, I'm just not sure that you are going to see the results you hope to see from your version of the rock sauna, esp. when there are other ways to accomplish the same thing. Heck - a heating blanket will do the same thing - put your rock in a bag, seal it and then wrap the bag with the blanky. It doesn't need to be high tech to work.

But if I had listened to those who didn't think many of my idea's wouldn't work (not just here, but with all the other things I do too), I'd simply be a sheep following the herd, and I'd learn nothing new
So go for it, document everything, and if it looks like it might be working, then great - we can run experiments to see if others can produce the same results and if so, then you have found another new way to create rock

 

[Insane Reefer]

<a href=showthread.php?s=&postid=10568400#post10568400 target=_blank>Originally posted</a> by Neptune777
I know what you were saying.....in the upper chamber. It doesn't matter...if the cement is moist it will create acids when in contact with CO2.....as well as any consensation dripping.

I don't follow your acids=alk surface..... Acids + alk surface (fresh cement)= neutral not well hydrated cement.

The suggestion from Mr. Collins was to add dry rock into a CO2 chamber.

I'm not sure I understand what you are saying...


But this is what Mr Collins wrote to me on it several months ago:

The first and most common would be to continue the moist curing for a
sufficient period that the concrete has become so dense that the
alkalinity of the material can not be leached from the matrix, and the
alkalinity of the near surfaces ahs been leached from the piece. This usually
happens somewhere around the 30 day mark, and has the benefit of
allowing further cement hydration giving the material a higher strength than
materials that are air dried.
It is also appropriate to begin to
provide a fresh water bath (exchange the water in the curing chamber) at
around 2 weeks of age and every few days after until curing is complete.

Another approach would be to moist cure for 3 to 7 days and then alter
the pH of the concrete material by exposing the surfaces to CO2 gas.
The CO2 gas reacts with the calcium hydroxide produced by the cement
hydration process to produce calcium carbonate which has a lower pH than
the original concrete mixture. Since CO2 gas occurs naturally in the
atmosphere, simple air drying will do this over time. The problem is that
it will take a very long time to carbonate the surface. In practice if
you wish to accelerate the process you would need an environmental
chamber so that the concrete could be exposed to pure CO2 gas under a
pressure environment. While this might be effective, I'm not sure that its
worth the trouble to design and operate such a chamber.
Your suggestion for providing CO2 in the water may have some technical
problems. Combining CO2 and water produces what is commonly used as
carbonation for soft drinks. This combination of material is typically
referred to as carbonic acid which when placed in contact with hardened
concrete causes slow disintegration of the concrete surface, and as the
concrete surface is stripped away a fresh layer of highly alkaline
concrete surface is exposed.

And then what Nick, the director of a major testing facility in Britain said (repeated from above):

Even when fully hydrated (most concrete never quite fully hydrates - it
depends on the water-cement ratio) the concrete will still be very
alkaline. However, you can have an alkaline interior and a carbonated
surface. If the cement paste is fairly dense, this could act as an
effective barrier. NB: not the difference between dense paste and
porous concrete - you can have both. I mean the cement paste component
is dense but the concrete could still be highly porous if eg: you have
a uni-size aggregate and a low ratio of cement to aggregate.
__________________________
a) instead of using vinegar, try using fizzy water. Carbonated water
contains carbonic acid; that will reduce the alkalinity a bit and also
provide some carbonate to help make a thicker carbonated layer at the
concrete surface.

Notice Collins time-frame of 3-7 days.
I think this also ties in with what Mr Wilson was saying about carbonate too.

My thought is that adding the co2 to the humid "atmosphere" will allow quicker penetration and thus quicker carbonation, esp when both replies are sort of combined.

I could be wrong, but that is the way I'm seeing it...

 

[Neptune777]

<a href=showthread.php?s=&postid=10568708#post10568708 target=_blank>Originally posted</a> by Insane Reefer
I'm not sure I understand what you are saying...


But this is what Mr Collins wrote to me on it several months ago:


And then what Nick, the director of a major testing facility in Britain said (repeated from above):


Notice Collins time-frame of 3-7 days.
I think this also ties in with what Mr Wilson was saying about carbonate too.

My thought is that adding the co2 to the humid "atmosphere" will allow quicker penetration and thus quicker carbonation, esp when both replies are sort of combined.

I could be wrong, but that is the way I'm seeing it...

I see, and you are correct. I was thinking in terms of using Micro silica.....which causes the formation of calcium silicate hydrate (lower pH) instead of the calcium hydroxide (high pH) during the cure. CO2 is not needed or wanted during this type of cure. However, if you use the traditional cement cure without Silica Fume then the CO2 would be very beneficial as stated in your response.

Water + Portland Cement = calcium silicate hydrate + Calcium hydroxide.........use CO2 during the cure and the calcium hydroxide becomes calcium carbonate.

Silica Fume + Portland Cement + Water = calcium silicate hydrate (CO2 is not necessary since calcium hydroxide is greatly reduced or gone)

 

[Insane Reefer]

And now for something completely different...

I tried to make pseudo branches like you did, Neptune. I used a mix of 1cement 1sand 1OS 2perlite. I made it slightly wetter then an Ol Skool mix. I still don't see how you get the dramatic points - I'm still stuck in porous mode, I think. The only thing I can think of is to make this more like a chunky brownie batter in consistency, so you can almost pull chunks off the mix.
Granted, working in the micro-scale sucks, especially when trying to mimic the shapes of larger pieces, but there must be some ancient chinese secret I am missing

I think the piece I just made will be the piece I use in my tank, if it fits, as I am very tired of trying to make the mini-center piece, and just want to get on to big rock that I don't suck at as much.

Because of it being perlcrete, and having such small branchy bits, I am going to leave it in the sand for 48 hours to prevent me breaking it, but will post a pic once it is out, good or bad.

 

[mmm55645]

I noticed the local HD sells pellitized and pulverised limestone, apart from aesthetics of the rock surface should I use one over another?
LOL the sales associate told me that the store did not carry Pulverised Limestone(and looked at me funny) and told me to look for it at speciality stores. He told me three other places to go, but when I walked down the store a bit, they had it in stock!

The rock at the pet chain still has the cardboard tag tied around it in the tanks with fish; wow that is an eyesore. It really creates the illustion of a natural reef seeing the tag tethered to the rock floating in the current. I don't know if they are trying to avertise the brand of rock or if they just don't care.
The rock is red but has spots of white and another shade of red. I am wondering if the white is from white sand added to red mix when it was wet.

Another thing, what quanity of perlite do you guys buy at a time, do you buy a small bag? I saw a small bag at HD.

 

[mmm55645]

just looked through the last few pages - must have missed it somehow before - the conscensus is to not use limestone as an aggregate?