How do you make a stone good enough to build a house with?

Discussion in 'Designing, building, making and powering your life' started by sun burn, Jan 22, 2011.

  1. DonHansford

    DonHansford Junior Member

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    First thing first - agricultural lime is NOT building lime. Do not expect it to work in concrete, either with or without cement. So, if you want "how it IS done" (with cement), then read on.

    This will give you a chance to build something you could use as a fence post, traffic stopper, one side of a door frame, a house stump, or lots of other things. It will give you a chance to become a little bit familiar with concrete, without being a critical item.

    Materials needed:

    Sand

    Gravel (20mm bluemetal is the standard)

    (You may be able to get a mixture of sand and gravel, often called Builders Mix, or Concrete Blend)

    Bag of cement

    Scavanged timber from a building site or somewhere , enough to make a box, or mould, roughly 1.8m long by 100mm wide and 100mm deep.

    Release agent - fancy term for something oily that will stop the concrete from sticking to the timber. You can use veg. or other oil, diesel, old sump oil, or a commercial moulding release product (but I've only seen it in 20 litre drums)

    Reinforcing ("reo") - this is the "ferro" part of ferrocement. Offcuts of reinforcing mesh from building sites is good. It should be tied together in such a way as to make a single piece. Rolled up chicken netting will do, but won't provide a lot of tensile strength. If you use scrap metal for this, make sure it is not too rusty. The reo should not be exposed when the concrete is poured, so it should be at least 2 inches (50mm) shorter than the box, and narrow enough that it will be half to threequarters of an inch (15-20mm) from the sides of the box when it is laid in.

    Wheelbarrow

    Shovel

    Rubber mallet, or a hammer and a lump of wood.

    Trowel (or you can get by with a piece of board)

    Water

    Small sticks (about pencil size) about 3 inches (75mm) long - see Step 7

    Small sticks about 5 inches (125mm) long - see Step 7

    Wire - to tie the reo together

    Concrete mixer (optional, but highly recommended).

    Step 1. Make and oil the box

    Step 2. Sort out the reo, and lay it beside the box

    Step 3. Dampen the inside of your mixer and/or wheelbarrow. Try to never let wet concrete touch anything dry. Not only is it a bugger to clean, but it accelerates the chemical process that sets the concrete.

    Step 4. Mix the concrete. A standard mix is 3,2,1. (3 parts gravel, 2 parts sand, 1 part cement). If using pre-mixed sand & gravel -"concrete mix" use 1 part cement to 5 parts concrete mix.
    All shovels-full MUST be the same! Mix the dry components first (in the mixer or the wheelbarrow), then add water gradually. Be careful, because the difference between a "dry" mix, and a "wet" mix, is about half a cup of water.

    Step 5. After the concrete is fully mixed (no lumps, just like mashed spuds), pour it into your (damp) wheelbarrow and transport it to the box.

    Step 6. Shovel enough concrete into the mould to cover the bottom to about 1 inch (25mm)

    Step 7. Put your reo into the mould. The concrete mix should be stiff enough that your reo doesn't sink through it, but sort of floats. If the mix is too wet, you will need to build little "rafts" using the small sticks to make sure the reo floats. The sticks and especially the reo, must NOT touch the inner walls of the box. If it's still too wet, use the longer sticks across the top of the box, and some wire to tie the reo up.

    Step 8. Pour or shovel the rest of the concrete in, making sure the reo does not contact the box.

    Step 9. With your mallet, or hammer and block of wood, work your way around the box, giving it a series of hits, to settle the concrete down into all the corners.

    Step 10. Clean up. Do this now, or there will be tears before teatime. Wet concrete is easy to wash off - dry concrete is an absolute bugger to clean.

    Step 11. Store any un-used cement powder in a sealed container - even one of those $10 rollaway plastic containers will do for one or two days (not much longer, though). Did I mention cleaning up?

    Step 12. The top surface of your concrete is now starting to "go off" - use your trowel, or piece of board, to float it to a nice finish. Don't overdo it - every pass you make will draw more of the water to that surface, and can result in a "chalky" finish.

    Step 13. (Next day). Cut the wires and remove the top sticks (if you used them in Step 7). Roll the box over and give it a few good whacks with the mallet / hammer & block. If you oiled it well, it should separate from the post/beam. Lift the box away, and give it a good hose down, then oil it up for the next time. Now you can pick up your post (careful, it's still a bit "green") and decide what you want to do with it. Just don't drop it on anything hard for a few months, until it is fully set.

    I hope that helps to give you a "how it IS done" that will let you begin to experience working with concrete.
     
  2. sun burn

    sun burn Junior Member

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    Heavens, i've only just found farago's posts above. For some reason they didn't show up when i was reading pebble's or Don's posts. He's probably answered the question i was looking for but it might take a moment to digest it.

    Don if you read it that's probably why you are confused about what i was asking for. I wasn't asking how to make concrete. I know that, its just that i haven't done it. I was asking how to make a mortar using lime. I also understand that agricultural lime is not the same as hydraulic lime which is the lime i was asking how to use. But as I just said, perhaps farago has told me above. This is not hte first time i've missed out on reading some posts. I don't know why it happens. It must be something to do with timing.
    al

    Looks like i haven't described how i will make the ferrocement in this thread either. It is LAMINATED ferrocment which is a particular type of ferrocment unlike the traditionalmethod using rebar and wire like chicken wire or whatever you have to hand, this method uses only expanded lath, a fine small wire used for rendering. As i said its uses a mortar not a concrete to hold it altogether. So there is no gravel. (Gravel is not used in any ferrocement methods as the stones would not pass through the wire. )That's why i am interested in a lime mortar if i am to do it wihtout portland cement.

    Anyway for laminated ferrocement, you lay 1/8inch or mortar on your mold base if you are working on a plank as i would be. Then you presss in the lath. Then you lay another 1/8 inch of mortar so that it coats the lath competely. Then you lay another layer of lath. More mortar, more lath and finally a layer of mortar. Using this method the lath should be completely coated with no air pockets. This is supposed to be one of the advantages of this method over the traditional method which had all the wire tied together before any mortar was applied. So in that case, some of wire was left uncoated and it would rust causing the ferrocement to become weaker after some years. Also this lath is galvanised so that's another things that will help prevent rusting. You don't need to use rebar in this method.
     
  3. sun burn

    sun burn Junior Member

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    Well Farago, thank you for your effort in writing all that out. I thought the answer to my question would be somewhat simpler. I have read it through only once at this point but I have a pretty good idea that this method is not suitable for me or my property. Unless I can buy hydraulic lime that is affordable to make a mortar with, i will just carry on with portland cement.
     
  4. DonHansford

    DonHansford Junior Member

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    Thanks Farago - excellent post! :clap: I'd love to spend some time with you, learning that clay/ash technique.

    Sun burn - I think the issue regarding posts is because the "newbies" first few posts have to be approved by a a forum moderator before they are posted. I just went back myself and found Farago's post - very informative.

    OK - now I have a clearer picture of what you are planning. The biggest challenge I see, is working out the amount of flexibility you will get for the thickness/number of layers. Perhaps make a couple up using OPC first (since it is easy to get). I would probably use Brickies Loam instead of pure sand - it has a bit of clay in it which would have a pozzolanic effect. You will need to sieve it, of course. Also make sure the water you use is clean (keep the ducks out of it :) )

    Start with 4 loam to 1 cement (use buckets/tins to measure out to maintain accuracy).

    When mixed well, it should "stick" to a trowel (or your hand) when held upside down, but fall off if you shake it. I'ts a bit hard to explain, but you will get a "feel" for it as you go along.:nod:

    I assume your mesh will come in 1200 x 2400mm sheets? I would suggest you make your test planks 1200mm long and about 150mm wide. Too much bigger and you run the risk of having the plaster mix in the mould starting to go off before the next mix is ready. It also minimises the outlay if you get a "dud" before you get the process right.

    After the plank has set (at least 24 hours for a start) remove it from the mould, place it between two bricks, and walk, hop, skip, jump all over it and see how much (if any) deflection there is.

    If it is rigid enough, then you can look at making one using half & half cement/hydrated lime as a comparison.

    If you then want try with lime alone, I would suggest you find a local plasterer and ask about a supplier, or even if he could sell you some lime. If you turn up on a Friday afternoon with a box of beer, you'll probably be able to get heaps of info as well! :p

    Hope that helps a bit 8)
     
  5. sun burn

    sun burn Junior Member

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    What is OPC?

    What is the pozzoloaic effect. (no need to tell me what pozz... is. Just tell me what the effect is.) Does it retard setting?

    I think 150mm is too narrow to be useful unless it means its going to be about the weight i can lift. 1200 sounds ok. Anyway i shall try these ideas out and find out firsthand. Its 2400 x 700mm

    I don't really understand this. Aren't i trying to replace the portland cement altogether?
    Secondly, why hydrated lime? Aren't I supposed to be using hydraulic lime? Isn't hydrated lime not suitable. I thought that's what I've been reading.

    What do plasterers do with the lime?

    As it happens, friends are building a house across the road from us. It won't be too much longer, i guess, before the plasterers will be there. Block houses go up so fast. At the moment they've just laid the slab.
     
  6. sun burn

    sun burn Junior Member

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    Farago,

    In response to this, it seems you haven't much experience with writing. I found reading your posts above quite difficult. I haven't written a book but i've some experience in writing.

    While making a video or film for youtube is not a bad idea either, don't give up writing a book. There are two possibilities i see here and maybe more. The easiest one is to get a ghost writer or writer to work with you, ie to partner you in the book. Such a person might interview you at length and write the book for you.

    If you don't want to do that but you want to write the book yourself, then what you have to realise is that writing a book is not usually done in one go. There are many drafts that have to be done. Much cutting and editing and tightening of the text. As a writer you need to get into the head of the reader and think about what you've written from their perspective. Does one point lead to the next. Does it make sense. Is it clear. This is not an easy skill to acquire. I learnt it after getting my draft thesis shredded by my superviser. To be a good writer, one needs to read many books first.

    Also I don't think making a film or video is any easier though it may be quicker. I've seen quite a few youtube vids now and some are excellent but many leave a lot to be desired. To do a good of job of that, i'd recommend at least looking at a lot of them and identifying what works and what doesn't.

    In the meantime, why don't you start offering workshops and classes in the techniques. Maybe particularly some builders would be interested and not just people like us. But even teaching is not straightforward.

    If you've got knowledge that you think should be passed on, but don't have the skills to communicate it well, then get someone to help you. Also why not take a look at the book i've mentioned somewhere. Its called Building with Lime by Stafford Holmes. Its an introductory book. He is apparently an expert in conservation techniques using lime. You will probably have to order it but perhaps your library will buy it if you ask them.

    I"ve also realised that I've just missed out on Warren D's posts too.
     
  7. sun burn

    sun burn Junior Member

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    Warren, i realise now my title was a bit misleading. But i think my opening post is fairly clear about what I was asking for. Mistakenly, I didn't think it necessary to describe the house I am hoping to build.

    I have said several times I am asking for a mortar recipe. I have described the mechanics of the making of the stone (concrete is a stone too don't forget). Mine is a ferrocement stone made of mortar and metal lath.

    I think my first post could be clearer but it does say all of that which is pertinent. I said i was making a stone using the ferrocement method.

    I have said i need it for a floor to walk on. I said, I MAY make some walls too.

    Sorry for the confusion.
     
  8. eco4560

    eco4560 New Member

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    Yeah sorry about the delay - it was in the moderator queue awaiting approval, but we are still dealing with BUCKETLOADS of spam so it takes a bit longer at present. Hoping the spammers eventually get bored and go and do something else with their Viagra....
     
  9. eco4560

    eco4560 New Member

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    You should get someone to do some video or photos of your process too sunburn. I can't wait to see what your research comes up with once you turn it into solid structures!
     
  10. DonHansford

    DonHansford Junior Member

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    Ordinary Portland Cement - sorry, I thought I'd used that acronym before :cry:

    Non-tech answer - it makes the mortar stronger

    My idea there was that these are test pieces. You might as well practice on $5 pieces, as $30 ones. If they turn out fine, you can always use them for stair treads, or duck ramps, but if they don't work out, you haven't thrown away lots of time, money and effort.

    Patience, little one! :) Crawl, walk, then run. Using cement first will give you a quick, easy intro to the type of skills you will need to learn. Using a 50/50 mix next will then let you get a feel for the difference lime can make.

    Hydrated lime is the cheapest, easiest to source lime additive for mortar/plaster. (From lime.org)Mortars made with lime and cement exhibit superior workability balanced with appropriate compressive strength, as well as low water permeability and superior bond strength.

    They add it to the cement in their plaster to make a smoother, more weatherproof plaster that is easier to work with.

    Get your practice "planks" made before the plasterers arrive - it will make it much easier to talk with them if you can show them an example of what you are doing. If there is a plasterer among them who is middle-aged, he's quite possibly done a fair bit of work with hydraulic limes and could be invaluable for advice.
     
  11. sun burn

    sun burn Junior Member

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    Don. Ok.

    Eco, I will take plenty of pics of my project don't worry but i think a video would be good. Maybe I can persuade my sister to buy one and use that. No, on second thoughts, i doubt it would work. She wouldn't go for it. I'd have to buy my own. Given my limited funds, we might just have to be satisfied with stills. But eco, don't be impatient because I know this is going to take a really long time. I will feed you dribs and drabs as they happen but even then, it will be really slow. At the moment, i am in go slow mode. Today i have to plant the bamboos i got yesterday and I don't feel like it very much i must say. I think i might be due for a trip away to liven me up. Trips always give me a big boost of momentum. A week somewhere would be good. hmmm. maybe i'll go for a drive up to cape tribulation or out to chillago... the latter i think as cape trib could be a bit wet right now.
     

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