[Ferro List] dougs fc

[Doug Lacy]

The Parabolic Stress Skin Process

 Starts with rolls of welded wire remesh.  This is the ten gauge steel, welded in roughly 6 inch squares, that comes in the 150 foot rolls in most hardware stores.  Often called 6-6-10, Concrete Steel and a few others.

The steel is cut in short pieces and then folded into five foot long wire frame blocks.  The blocks are five feet long because that is how wide the roll of steel is.  Usually we do 7 inch blocks and 12.5 inch blocks.  They resemble little wire cages that have four flat sides.  We hog ring these together mostly these days, we use to tie them by wrapping the heavy wire around with a little pipe, but now we use mostly the hog ring gun.  An SC7 works great if you use the slightly heavier clips than what it is designed for and also the SC7XE works even better especially for hanging the lath.

I wire these blocks together like legos to make structures that are usually curved in many directions to achieve a big structural goal with the least amount of material.  Economy of form, and economy period, is a big theme.  

I usually put a bunch of nicey sculptural details like, sconse details (strange lampshades), planters, water features, gutters, nichos, sea shells, waves, using various forms of flat remesh ribbons to capture certain lines in the complex forms.  These flat peices of steel remesh have aquired names like single rods, single rod centipedes, double 6 bandaids, ass-ended centipedes and such to describe the shapes needed to make it easy to tie into the form in progress.  We also have a tech for taking large line forms from graph paper into reality and also making small segments of curvy shell that have accurate curves in two directions.  

After the wire armature is done, we tie down a nice tight skin of expanded metal lath, the 2.5 guage which is the medium weight stuff that is most comenly used in stucco.   
Once all the loose ends are tied down with both wire ties and mostly hog ring ties and double checked, we plaster this metal form with a high-strength composite.  The composite is made by throwing two buckets of sand in the mixer, adding a bag of quality Portland cement, adding 2.5 gallons of water, adding 12 to 16 ounces of Eucon SPJ, Walk away for about 3 minutes (most important and difficult step)
  

At this point, the portland will have reacted in a way that it may reveal exactly how hydrated it is by showing one of four stages of plastic consistancy.  This eliminates any guesswork on how much water is really interacting with the cement which by-basses the function of knowing the exact WCR with a more direct and usefull measures of workability as plaster, with the absolute minimum of water added.

If it is still churning around in mostly balls of rolling chunks of various sizes, you are still almost there and a two to ten ounce mist of high pressure water added to the mix at this point will cause the mix to change radically in consistancy in a minute.

 If the mix has achieved a marked plastic consistancy and is still rolling around in the mixer and trying to ooze off of the paddles but mostly flops around like runny taffey, you are almost there and have stopped adding water at just the right time and a tiny shot of water will bring it to perfection.     

When the mix is still being scooped up off of the bottom of the mixer but mostly rolls off the paddles before they rotate all the way around, you are right on the money.  

If the mix is drips off of the paddles in stringy drips and while it is mostly puddle in the bottom instead of churning around in your 9 cubic foot horizontal mortar/plaster mixer, have someone take the water hose away from you and grab a hold of the sparkplug wire on the mixer motor to help you remember that you have just added too much water.

Now add a half a bag of Micron 3.  This will make if very runny but it is important that nothing is added to the mix until the super p. has done its magic.
When the nodules in the runny mix become less noticable, after about a minute, the time it takes to stuff a container full of fibers, add about 1.5 compacted quarts fibers of PVA rec 15 - 8 mm fibers and about 1.2 compacted quarts of Forta Ferro 3/4 virgin fribulated fibers.  I am not sure if they are still virgins after this mixing.  
Now add another two full five gallon buckets of sand, another 1/3 bucket of sand and then go fluff-up a bucket of Mearlcell 3532.  To do this, you just add one ounce of the concentrate to 40 ounces of cool clean water in a five gallon bucket.  With a drill paddle that has a 10 inch by 10 inch roll of metal window screen rolled up like a newspaper and wired on to the bottom of the paddle, stir the mix, being carefull not to let any slosh out, until if fluffs into a nice creamy white mix.  Keep mixing it until the very slight yellow sheen it has in the sun, not noticable by everyone, turns into a blue sheen.  Pour it into the mixer and wait another minute until you get some flat grey coloring.   

We plaster the shell with this mix at about 3/4 of an inch thick and later inject the whole hollowish form with cellular concrete, for homes that is.  I have only used between a 5 to 6 bag per yard mix of neat cellular concrete which might be a bit costly from a home project point of view, but lower density, less expensive and more insulating mixes will probably work fine.  If I were you, Janoahsh, I would practice on a couple of these low density mixes to get an accurate cost for your project and an accurate feel for the structuralness of the fill.  It could mean the difference of thousands of dollars.  
We almost finished an interesting sculpted wall project today and more to come.  

Here are some related videos.  http://youtube.com/user/ShambhalaVillage

More Project Info will be posted soon and soon I will be able to edit the website.
Doug
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