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+--- Thread: ferrocement using cinders? (/showthread.php?tid=8873)
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ferrocement using cinders? - csgray - 06-17-2011
Has anyone here experimented with using cinders or other locally available material, instead of sand, to make ferrocement? I am interested in doing a small ferrocement wall/fence/gate project on a very uneven stretch of ground and would like to use as much local materials as possible, and while the Big Island doesn't have much sand we sure have a wide assortment of cinder.
Carol
RE: ferrocement using cinders? - leilaniguy - 06-17-2011
I've tried it for small flatwork projects, a couple of stairlanding slabs and to patch recurring driveway pukas. The cinders are soft, so it wears down over time. Where I used it to cement rock together for walls it has held up fine.
RE: ferrocement using cinders? - DanielP - 06-17-2011
Portland cement bonds to the surfaces of the sand and gravel, holding them together; The finished mix will only be as strong as the aggregates used. Cinder is not strong and has lots of surface area. More cement needed for a relatively weak mix.
Dan
RE: ferrocement using cinders? - csgray - 06-17-2011
Strength isn't a big issue since we are talking about something that is more of a fence than a wall, all it will need to hold up is itself. It does need to hold together though.
I've been fascinated with the possibilities of ferrocement for a long time and have a very steeply sloped hill in between two short level stretches where I would like to erect a dog proof barrier. Fencing it to keep in my Houdini hounds would be complicated by any method, but the flexibility of ferrocement made this project seem like a perfect marriage of need and interest.Plus the ability to curve around existing landscape elements with a more organic form is really appealing.
Carol
RE: ferrocement using cinders? - Peter Epperson - 06-21-2011
To be "ferrocement" the design would need to fit certain criteria. A dense aggregate is one of those requirements. Cinders are too soft to meet the standards of real ferrocement but would probably make a fine ferrocement-like material that would be suitable for the project that you have in mind. The lava rock that Glovers turns into sand would be a much better choice and would be a lot easier to work with. I've made ferrocement fences using diamond lath for the reinforcing and then troweling onto it a mixture of 2) parts #4 sand, 1) part mortar sand, 1) part cement and 1/10th) part hydrated lime. That will give you a very strong and workable mix.
Let's try that recipe again if my description isn't clear. If you're going to mix a small batch in your wheelbarrow: 50lb. #4 sand, 25lb. mortar sand, 25lb. Hawaiian cement and 2.5lb. lime. Add enough water to make it workable so that it's easy to trowel and will stick to a vertical wall. Remember that the more water you add, the weaker the final product will be.
www.pacificgunite.com
RE: ferrocement using cinders? - csgray - 06-21-2011
Thank you Peter! That is what I was looking for, a local source for materials for this project and having a "recipe" will be a big help too. How far does a wheelbarrow's worth go when doing fences?
Carol
RE: ferrocement using cinders? - Peter Epperson - 06-21-2011
"Thank you Peter! That is what I was looking for, a local source for materials for this project and having a "recipe" will be a big help too. How far does a wheelbarrow's worth go when doing fences?"
A cubic foot of concrete weighs about 150lbs. The wheelbarrow recipe that I gave, plus water, would probably produce around 120lbs of mortar. You could cover about 15 square feet at 1" thick. You might be able to keep the wall down to 3/4" thick or less if you are careful with your wire tying.
RE: ferrocement using cinders? - Kapohocat - 06-22-2011
Pete -
Can you add any recycled glass to replace part of the sand?
(I saw a "pic on the internet" of a wall made with the glass. "pic on the internet" is the phrase most dreaded by my husband!)
-Cat
RE: ferrocement using cinders? - Peter Epperson - 06-22-2011
"Can you add any recycled glass to replace part of the sand?
(I saw a "pic on the internet" of a wall made with the glass. "pic on the internet" is the phrase most dreaded by my husband!)"
We did try glass as aggregate some time back. ConAgg agreed to test it for me but it turned out to be very weak. I think that part of the problem was that the edges of the glass pieces are too smooth and don't make a physical bond with the cement. We ended up mixing the fine glass powder with cement and latex binder and brushed it onto our septic tanks as a protective coating. It worked well for that and the tanks sparkled in the sun which was cool.
RE: ferrocement using cinders? - Smith - 07-17-2011
All good advice! I've worked on a fair amount of experimental ferrocement projects.
Most were walls, both house and fencetype walls....using nylon fibers as "mini rebar" gives great strength
with thinner coating of the substrate. I've got the best supplier for the fibers for ordering,if you're interested.