Weight, and stability when tilting

I’ve been perusing the net reading up on papercrete; what people have done and what they think. I ran across a bit from someone who asked why anyone would want to pour a whole wall at once. They stated it would be heavy but it could probably be done with sufficient rebar to keep the wall structural intact while being lifted into place. Rebar? Okay, I can see where that could be a good thing if you didn’t already have a support scheme in mind for the wall or you expected the papercrete portion of the wall to be structural.

As to the weight, 60 pounds of paper, 65 pounds of sand, 94 pounds of concrete and 1334 pounds of water makes a pretty hefty wall (1500+ pounds). But a bunch of that water is going to drain away when the slurry is poured into the mold, then a bunch more is going to evaporate as the wall cures and dries. So say you’re left with 10% (actual dried wall content should be closer to 2% – 27 pounds) of the water still in the wall. That’s only 150 pounds! That would give you a total papercrete wall weight of 369 pounds per mixer load of water. So if a wall takes two mixer loads, you’d have a finished papercrete wall weight (12’x8’x6″) of around 700 pounds. Not too shabby! I’m asking Nolan what he thinks a ferrocement wall would weigh.

I’ve seen mention of people making papercrete logs (actually, really long bricks) that break in two when lifted, so I can see tensile strength is an issue. Being able to use the layup table to tilt the wall to an upright and pickable (a lift is called a “pick”) position is going to save me from adding structural steel to the papercrete layer. I may cheat and add one layer of chicken wire between the two batches of slurry as insurance, though having the papercrete layer tied to the ferrocement layer should be all the stabilization the wall would ever need.

Nolan says a square foot of cement weighs 130 pounds. If I assume my ferrocement layer is going to be 1″ thick, that gives me a square foot weight of 10.33 pounds. That puts the ferrocement layer for my sandwich wall at approximately 800 pounds. I’ll bump that to 850 pounds to give myself some wiggle room. I’m not calculating the full 12′ x 8′ because I have to have the reinforcing exposed around the edges for connecting to foundation, bond beam and reinforcing of the adjacent walls. Leaving 6″ exposed all the way around may be too much, but for testing I’d rather have too much exposed than not enough to work with. I can add concrete, I can’t necessarily take it away.

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