bcotton's ferrocement system

bcotton

Disclaimer, before this project, i have zero experience with cement or stucco or ferro. This may be a thread on how not to build a ferro system as much as it could be a thread about how to build one.

This is my 5th system. (I have moved a few times the last few years), but i am now in a place that i plan to be for several years. I have traditionally used ibcs, stock tanks, 55 gallon barrels and wood grow beds to build my system In this case i want something that i can shape better, age better and HOPEFULLY make it look better.

I plan this to be a multi year project.My short term plans are to build a 700 gallon fish tank and 1 8'x6'x1' grow bed. My long term plans are to add two more tanks with similar sized grow beds, and then to cascade additional grow beds down the slope my back yard for sort of a waterfall effect before emptying into a [yet to be designed and very large] sump.

Without further adeu, Pictures of the beginning of my 700 gallon ferrocement tank.

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File comment: I didnt want to poor a foundation. The wood is just a frame to frame the cement base

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File comment: A remesh sheet,reinforced by rebar, wrapped in chicken wire and some rebar 'L's protruding.

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File comment: cement base poured,

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Charlie

Ill be watching with interest, I love this stuff and would like to have a go at it one day. We have a member here called stucco, check his thread out as he has done some incredible ferrocement work.

bcotton

Yes charlie, stucco's ferro examples are my inspiration for certain. I have read stucco's thread and between his duck enclosure and the ferrocement thread i seem to think anyone can do ferro. We'll see.

I am not happy with the smoothness that i was able to achieve on the cement base. There's obvious ripples and unevenness. I hope i get better as i get used to working with this media. I adopt a motto based on a line from movie the big lebowski. "nothing is f'd here dude" and i press on.

I continue to water the cement base in the morning and at night. I do not keep a cover on it. Temperatures range from 50-80 degree F throughout the night-day.

I have started adding the frame for the tank. I started by tying 3x 4'x8' remesh to the protruding 'L's. Then Reinforcing the remesh with 8 x ~4' rebar at each "L". Then i coated the inside and outside with steel mesh horizontally 8'x27". I thought the mesh was 2' wide but it turns out it is 27". So when i stacked it on top of each other i got some extra room at the top. I am not worried about this. It makes my tank a little bigger, The top wont have much pressure on it and there will be an extra 6 inches above the water line so maybe i dont have to cover the tank to mitigate jumpers.

brian

MartinC

This looks really interesting - "Subscribe topic"! :-)

Regards, Martin.

bcotton

The ground is not completely level. I thought i was going to be able to adjust for this after the fact but that is not going to be possible. The base is already 400 lbs and is too heavy for me to work with on my own. Hind sight. I should have used some of my leftover expanded shale to level out the area before setting down the base.

I have added 3" couplings to top/sides of the tank for exits. The inside of each coupling is slip and the outside is threaded (so they can be easily capped) I plan to only use one of them to empty to the first grow bed but I want the flexibility to change my mind and the meta-design later.

I started applying mud on the inside of the tank. I am not really measuring out the ratios properly. i am using about 1.5 gallons of gray portland cement type I/II and 1 gallon of water. After i get the water and cement pretty well mixed, I add a 50 lb bags of play sand. I usually add between 1/8 and 1/4 more gallons of water to get the consistency right.

I am applying a little less water than maybe i should so that the mud is a little thicker than it should be. I feel this is necessary to get it to stick to the mesh. I am scooping it on in clumps and I cant smooth it out very much because the smoothing action causes the mesh to vibrate and messes up other areas. I stopped fighting myself and decided to just get the clumps on so that tomorrow when i come back the mesh will hopefully be more rigid due to the dry cement and i can press more and smooth without the mesh vibrating.

Takeaways,
1) Level your work area before you begin
2) I think i can secure the mesh better by tying it to the remesh and rebar vertically instead of wrapping it around the frame horizontally (which seems to promote sagging, gaps and vibrations when applying mud.)

MartinC

Hi bcotton,

This is really impressive. Would you mind giving an idea of costs for the different elements going into the construction? It would be really useful to be able to compare these costs with those of buying a conventional tank of the same capacity.

Thanks for documenting this process it is really appreciated.

Regards, Martin.

bcotton

Martin,

I will put together a complete parts list next week once i am a little closer to completion. I will add dallas area home depot prices and calc my total but material costs may vary from region to region.

I started putting mud on the outside. I am able to apply it a little more even than on the inside but i still fail at smooth concrete. I have to apply the mud with trowel vertically because of gravity but then if i try to smooth it by stroking horizontally i get a grainy look, which still isnt smooth. I stopped trying to do the top half because i was getting vibrations again. I probably didnt use enough mesh ties. So i just tried to add mud to the bottom and go a little above the seam. I'll try to finish the first layer of the outside tomorrow.

MartinC

Hi bcotton, thanks, I look forward to more information on the parts and costs. I understand costs will vary but it will be good to have a ballpark amount.

I can imagine how difficult it is to get a smooth finish. I have worked a little in construction a long time ago and one of the skilled people you needed was the plasterer. To get the consistency of the cement to the right level of moisture and plastering it on the walls was a bit of an art form. The final smoothing was impressive as the moisture levels were so important. It had to be dry enough to stick on the wall but wet enough that when you applied some pressure it pushed water out of the concrete onto the surface so that you could use it to smooth the wall. A well finished wall is more impressive than many people realise.

Regards, Martin.

scotty435

MartinC wrote:

The final smoothing was impressive as the moisture levels were so important. It had to be dry enough to stick on the wall but wet enough that when you applied some pressure it pushed water out of the concrete onto the surface so that you could use it to smooth the wall.

I've never tried concrete work and you comment made me wonder, if your a bit off in the water content of the mix, can you just spray the outside to make it easier to smooth?

Ronmaggi

There are sand-able finishes that can be applied after the fact.

Ronmaggi

Instead of smooth at this point, perhaps you should leave it notched, using the notched side of the trowel...

MartinC

Hi Scotty, I think you noticed from my post I am no expert but I remember the guys used to have a large soft brush sitting in a bucket of water and they would use it to flick water onto the wall until they had the right moisture level to work with successfully.

I am assuming if you overdo it then it gets wet enough to slide off so use my advice at your own peril. ;-)

Regards, Martin.

Sleepe

I have posted this one before but it may give you some idea of the technique and consistency. http://www.youtube.com/watch?v=U7IGsG0TzUo

scotty435

Thanks for the info Martin.

thanks for posting the video Sleepe, Doesn't look that difficult, just a lot of work.

bcotton

I patched up the inside where there were gaps, let it dry and then put a last layer on the inside.

I tried using "mixing sand" instead of "play sand." which is more expensive but seems to be necessary. It's a lot finer sand and i have found that it makes mud a lot more like the mud in the youtube video sleepe posted. It's smoother and easier to work with but it seems to set faster so i still have a lot of uneveness and lines because i placed the mud on the whole wall and then tried to work out the lines [but it was too late.] I think if i slow it down and try to smooth it out a little at a time i wil maybe have more success. I have to relearn the application because the properties are significantly different now.

It's also hard to smooth out a concave surface because my trowel is bigger than the surface i am smoothing.

I will finish the inside and fill it with water tomorrow.

The plan is to leave it with water for a couple of weeks for it to cure. I will eventually seal it with a yet undecided fish safe, non toxic waterproofer to keep it from leeching. (Most likely some sort of epoxy) I want to use white for sun reflection and so i can see the fish easily.

I dont need the inside to be completely smooth but i will be looking into grinding out some of the worst creases and un-evenness so the epoxy applies well.. Any suggestions are welcome.

I still need to put one more thin layer of ferro on the outside of the tank, I need it because some mesh is still showing and needs to be protected, but otherwise it's just for looks. I will practice making it smoother. I am pretty sure usingw hat i have learned i could make the same tank with only 60-70% of the mud i used on this one.

I will also start building my 6'x8'x1' ferro grow bed. I will be using a billboard liner instead of a sealer because it's cheaper and its going to be covered by gravel anyway.

brian

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