[papercreters] Re: Burlap-Crete (John Annesley's original post about it.)

In another thread, someone mentioned John Annesley's Burlap-Crete.

I knew John was a member of our group, and I knew he had posted about it previously, so I looked it up. Instead of just posting a link to his post on the topic, I decided to reply to it so that my post would quote his words entirely. So, here I am replying to a post that is over 5 years old. Better late than never, right?

The post below was written by John on March 4, 2008.
The url for a direct link to the page I got this from is:
http://groups.yahoo.com/group/papercreters/message/5432

Enjoy this trip through the way-back machine everyone. I sure hope the Flux Capacitor in the Delorean holds together for the trip home. Oh crap!... I better get a move-on. I see Biff headed for me.

--- In papercreters@yahoogroups.com, "John Annesley" <John@...> wrote:
>
> There's a few folks that have used burlap soaked in cement slurry and
> draped it over wire formwork, therefore being able to build a house
> with a similar approach as a large piece of sculpture. Another way is
> to stretch the burlap over an armature and paint a weak cement
> solution on it, building up layers-- which takes about forever unless
> you have lots of people. I've tried a bunch of different mixes and
> have come up with one that works so well its just about amazing: my
> exterior walls are made this way, 1,200 square feet!
>
> I found that portland and sand and water, in any combination generally
> don't do well for burlap-crete, as the result is fairly easy to crack
> and then powders and seperates from the burlap. I tried adding latex
> paint which was suggested on numerous web pages as a way to add
> elasticity, but it wasn't strong at all. I suspect in several layers
> either of these approaches could work, but I was looking for a thin
> shell that would be strong enough to use as a wall without building up
> layer after layer... I tried plastic cement, which is a bagged cement
> product with clay and other plasticizers and that worked fairly well,
> mixed 2 parts medium grit sand and 1 part plastic cement. However, it
> takes a long time to dry and in two layers is only so-so for strength
> and it does crack easily when moderate pressure is applied. Then I
> tried traditional sculpture recipes using 20 minute casting plaster,
> which in two layers was generally stronger than the cement-and-burlap
> products, and was rock hard in 20 minutes. The problem with that stuff
> is it isn't weatherproof at all, and dissolves in damp conditions and
> I was concerned about water vapor condensating in the wall, as it will
> in any structure when the outside temp is lower than the inside temp
> unless you have a vapor barrier paint on the inside of your walls or
> something similar. So then I tried 5 minute post hole cement, which
> failed miserably but did set up rapidly. It crumbled and powdered into
> oblivion very readily when even mild pressure was applied. I tried a
> bunch of other things, and finally tried rapid set non-shrinking
> grout, which in two layers (one layer half overlapping the next like
> shingles) is very strong, about as rigid as 1/2" plywood coated in
> stucco. You can crack it with a lot of force or a hammer blow, so I
> added latex conctrete binder to the mix and that added a fair bit of
> elasticity to it so that when it dried, it was tougher and when enough
> force was applied to break it, it would bend slightly before breaking,
> and only a fine hairline crack would appear as opposed to a large
> shattering pattern. In 30 minutes it achieves 3,000 psi compressive
> strength, 6,000 overnight, and 9,000 after 28 days. (That's what the
> bag says, Cement-All fast set non-shrinking grout.) It sets up
> underwater, is highly durable in wet locations, and has a sandy beige
> color when dry. The seams between pieces of burlap feather into each
> other and disappear, and when dry all it takes is dampening to be able
> to blend another layer of burlap-crete onto it without any cracking
> and the splice becomes seamless. If you add too much concrete binder
> (a latex glue), it will shrink when drying and cracks will appear, so
> I misted the walls for half an hour while drying, and came up with
> appropriate amounts of concrete binder to add. This stuff sets up
> quickly, and if you use a plastic or metal bucket you won't have it
> very long. Get a rubber feed bucket, a big one about three feet around
> and a little over a foot high. That way when the stuff turns into rock
> which it will until you find out what mix to use for your climate, you
> can flex the bucket and the stuff will drop out. I tried it on cold
> days and warm days and windy sunny days: each time I needed a
> different amount of water. The basic mix I found worked well was to
> use a plastic 5 gallon bucket to mix it in and then pour it into the
> rubber feed bucket for use with the burlap. The sacks of Cement-All
> are 55 lbs. and you can mix a sack in a 5 gal. bucket, but as soon as
> you're done mixing, pour it into the rubber bucket and clean your
> plastic one immediately. Using a 1/2" drill with a mixing paddle is
> probably mandatory, I hung mine from a rope at a comfortable working
> height so all I had to do was pull the trigger to mix the stuff. It
> depends on the brand of concrete binder as to how much of the stuff to
> use. Sika brand required 3 quarts of binder and 2 quarts of water per
> 55 lb. bag of Cement-All grout. Supercrete brand concrete binder is a
> lot thicker, and slightly less expensive, so that I can use 1 quart of
> it and 5 quarts of water. Put the binder and water in your plastic
> bucket first, then pour half the sack of Cement-All in and stir with
> your paddle on a drill for about 30 seconds, add half of what's left
> and stir again, and add the last of it and stir until creamy smooth,
> about a minute or two. Be sure you've got your burlap soaking water
> overnight, cut into pieces that will more-or-less fit in your big
> rubber feed bucket, about two-feet square works good. Ring it out a
> little and dip it in, working the Cement-All into it from both sides
> by turning the burlap over a few times. Work your hands around the
> bottom of the rubber bucket as the Cement-All will start to harden
> there but you can get it workable again by pressing it around with
> your GLOVED hands and it will mix with the water from the burlap. If
> it sets up too quickly, make sure your next piece of burlap isn't rung
> out so well, a little water goes a long way. Soupy is good, but don't
> go beyond pea soup consistency in terms of making it more runny.
> You'll need a ton of large wooden clothes pins to hold the burlap onto
> your wire wall, I used stock panels, but you could get really
> sculptural with this stuff. Because it really does set up FAST, I put
> the clothes pins onto the wire about a foot above where I'll be
> putting the burlap, so that it will be all ready to go the moment I
> need them. Oil the clothes pins, otherwise they'll become part of your
> project on a permanent basis. To hold the middle of the burlap against
> he wire, press the clothespins around the wire trapping the burlap
> against them, this leaves an interesting divot in your wall, which can
> be filled later with more Cement-All if you don't like the look of it.
> Seriously, if you overlap each layer half way, it ends up 2 layers
> thick and is as strong as a 'real' house covered in stucco. Then you
> can do whatever you want inside, out of the rain and sun and wind
> while you finish your project. It's non-flammable, too, and you can
> cut out the doors and windows as needed later on, using a cutting
> wheel or sawzall. I'm thinking of using it for a roof at about three
> layers thick, but it isn't cheap at about $18 per 55 lb. sack. The
> concrete binder is less than $10 per gallon, and only one quart is
> needed if you use the Quickrete brand. In an overlapping pattern, a
> sack will yeild about 25 square feet of soaked burlap. One person can
> work quickly enough to deal with the entire process alone if
> pre-planning is employed. Wear a dust mask while mixing the stuff, its
> dusty. When hard, its fairly rough in texture, but by dampening it and
> then smoothing on a thinned out layer of Cement-All with binder with
> your gloved hand, from the remnants of your rubber bucket full of
> stuff when there isn't enough left to coat an entire piece of burlap,
> you can even out the contours and make it nice and smooth. You can
> also add cement coloring powder to a final coat and trowel it or glove
> it on. I'm not at 'my' computer now, I'll add a follow up with
> pictures soon. John A
>




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