Inflatable concrete form (temporary shelter)

Discussion in 'Homesteading Questions' started by sisterpine, Aug 17, 2005.

  1. sisterpine

    sisterpine Goshen Farm Supporter

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    How young folks come up with these ideas while listening to all that ?music? and playing video games is amazing! Could it be that not ALL young people are lazy slobs who never stand up and move about LOL. This could really be a helpful idea if they can get it working though the current cement shortage (Japan is building the worlds largest dam so I am told) could present some additional challenges. Perhaps it could inflate and be covered with some other type of impregnated cloth that would harden....
     
  2. wy_white_wolf

    wy_white_wolf Just howling at the moon

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    They spray them with foam insulation first. Then lightwieght concrete after running rebar. The balloon form actually ends up on the outside and can be left on for a protective coating and/or stuccoed over if desired
     

  3. cc-rider

    cc-rider Baroness of TisaWee Farm Supporter

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    How do they get INSIDE the balloon to spray the foam? Funny mental image there.
     
  4. gobug

    gobug Well-Known Member Supporter

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    There are more ways to construct a cement shell than the monolithic system of using the airform on the outside with rebar and foam sprayed inside.

    Last summer we used an inflatable form provided by Lloyd Turner, the inventor (not Monolithic - they just own the patent for the rebar connector). The form had a flap door and was inflated with a small rented squirrel cage fan. We sprayed cement and PVA fibers on the outside using a ceiling texture gun (instead of a shotcrete crew like Monolithic). When the cement was about 1/8" it didn't need the form any more.

    The product mentioned here is a canvas soaked in cement. You just add water and turn on the pump. It is designed to be dropped from the air to those suffering catastrophes.

    I don't think it would work as well for a larger structure; however, it wouldn't be too difficult to get several and connect them.
     
  5. cc-rider

    cc-rider Baroness of TisaWee Farm Supporter

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    That did you use this structure for?

    I can imagine this new "invention" would come in handy....even if they were only tent-sized. Any port in a storm.....
     
  6. gobug

    gobug Well-Known Member Supporter

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    CC

    The structure was made as a demonstration. It was 10 feet in diameter and about the same in height. We stopped spraying when it reached a little more than 1/8 inch. It stood for a year at the home of the conference host. Then he had it torn down.

    Lloyd Turners "bubble house" has several bubbles. If you have ever looked closely as soap bubbles, when there are several, the intersections are straight lines. Lloyd built the bubbles one at a time, but made plywood intersections to flatten the form where doors were to go.

    Lloyd and his wife have lived in the house for more than 40 years and it has been featured on television. He is now selling or has sold it.

    Here is a link to his website:
    http://www.enchantedcreek.com/Artists/lloydt.html
     
  7. Rick

    Rick Well-Known Member Supporter

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    Hello Gobug

    I have several questions, if you don't mind.

    Can you tell me if these forms are available, and how much they might cost. How much longer than a year do you think it would have lasted?

    Do you have any idea how much it weighed, and what the cost was to build it? It sounds like it could be done in a weekend.

    Thanks,

    Rick


     
  8. Cyngbaeld

    Cyngbaeld In Remembrance Supporter

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  9. gobug

    gobug Well-Known Member Supporter

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    It is relatively easy to make your own inflatable form. The cost from Monolithic would be excessive compared to making your own. This is just one area they rake in the money. (monolithic > $1000, DIY < $100)

    The panels in an inflatable are all the same shape (they are called gores). Tyvek will work well as the material. Tape holds the panels together, but you could also sew them.

    If we wanted the form we sprayed to be permanent, we would have kept spraying cement until is was about 1/2 inch thick. Doing this without the rebar or other metal requires specific fibers (PVA or steel - not fiberglass). It should last many lifetimes. Weight depends on surface area. I estimate the surface of the shell we sprayed was 400 sq. ft. X 1/96 ft thick ~ 4 cu ft of cement. At about 160 pounds per cu ft, the structure was probably close to 600 pounds.

    Making the airform might take a long day for your first one. It would take another day to prepare the ground and mount the airform so it would be immobile. Maybe another day or part day to spray the concrete. All of this is dependent on size and the site.

    I have some pictures, but I recently took them off line to make room for this years' pictures.

    Gary
     
  10. Terri

    Terri Singletree & Weight Loss & Permaculture Moderator Staff Member Supporter

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    Out of curiosity, how does one spray concrete?
     
  11. Ozark-Dew

    Ozark-Dew AMDG

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    Wow, "paper mache" for grown-ups! this is very intriguing.
    I would like one for a chicken coop! cool in the summer!
     
  12. wy_white_wolf

    wy_white_wolf Just howling at the moon

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    From http://en.wikipedia.org/wiki/Concrete


    Shotcrete uses compressed air to shoot (cast) concrete to a frame or structure. Shotcrete is mostly used for rock support, especially in tunnelling. Today there are two application methods for shotcrete: the dry-mix and the wet-mix procedure. In Dry-mix the dry mixture of cement and aggregates is filled into the machine and conveyed with compressed air through the hoses. The water needed for the hydration is added at the nozzle. In wet-mix the mixes are prepared with all necessary water for hydration. The mixes are pumped through the hoses. At the nozzle compressed air is added for spraying. For both methods it is used additives like plasticizers and accelerators. Shotcrete is normally reinforced by fibers.
     
  13. Cyngbaeld

    Cyngbaeld In Remembrance Supporter

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    I think one would make a really fine tornado shelter, or root cellar.
     
  14. gobug

    gobug Well-Known Member Supporter

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    Shotcrete machines are powerful machines. Some pump 40-70 cubic yards per hour. I saw one in Las Vegas in July that had a dozen cement trucks lined up to keep it running. It takes an experienced crew to operate a shotcrete setup. They can be dangerous. And they are definitely messy. You have to cover everything anywhere near the area being sprayed. These machines require a huge air compressor - like 300 cfm+

    I have a Tyrolessa sprayer and use a standard 6 hp compressor with an extra tank and puts out 10 cfm. It's also called a hopper sprayer. The hopper holds about a gallon of cement and it takes about half a minute to spray the gallon. It works best to have someone mixing the cement, someone delivering the cement to the sprayer and someone spraying, but it could be done alone.

    When we sprayed the inflatable in Oregon last year, we used a home deport $60 texture sprayer. It was real slow, like a quart in 5 minutes, but it put a fine layer on the form, whereas the hopper sprayer would be like oatmeal.

    Shotcrete is not a DIY method, but for about 3000 extra dollars, the job is done in less than a day. Whereas, with the hopper sprayer you can do it yourself, but it will take a lot longer.
     
  15. hatwoman22

    hatwoman22 Well-Known Member

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    Gobug when I wrote you this is what I was talking about, you made it sound as though you had built a small demonstration dome not just a roof. Sorry for any misunderstanding.
     
  16. gobug

    gobug Well-Known Member Supporter

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    hatwoman
    sorry for the confusion
    I did help build a demonstration cylinder as described.
    I did not make the inflatable form, Lloyd Turner did.
    Making one isn't very hard to do, though. If I wanted to build a house like this, I would make my own forms instead of buying them.
    Gary