Has anyone done any papercreting/testing with one of those vibrator
probes that they use to get air voids out of concrete? When they pour a
large area like a dam, bridge footing, or roadways you often see them
insert a vibrating probe into it to get out the voids.
This could have an impact on the shrinkage/form of the block after
drying, the strength, water absorption, and the insulation value. Maybe
better, maybe worse, but I think it would be worth trying if anyone has
access to something like this.
Dan
_________________________________
Re: boric acid one more thing
Posted by: "mdumiller" mdmiller1@gmail.com mdumiller
Date: Sun Aug 12, 2007 1:35 pm ((PDT))
I haven't tested this theory, but I think the amount of water
reabsorption of cured papercrete is related to the amount of original
water in the mix as poured/used. As the water evaporates from curing
PC, creating airspace voids in the pC, rewetting will tend to permit
water back into these itsy spaces. The fibers are probably encased
in portland and don't absorb much, which is why a block that is
rewetted dries so quickly.
I'm guessing that if you took two identical just-poured pc blocks and
squeezed all the water out of one of them and let them both dry, the
one with the water squeezed out is smaller and of higher density and
probably won't absorb as much water. It contains less air space,
even though they both contain the same amount of paper and other
material.
On the other hand, if you don't put in enough portland to coat the
fiber, then the paper fibers themselves will saturate and become part
of the equation, and in this case, I think you're right.
In situations where you expect to have PC exposed to a lot of
moisture, based on this theory, it would be wise to compress the
blocks while wet to eliminate water. Obviously this could impact the
insulative properties of the finished product. And this is just a
theory, so don't do anything based on this untested crazy idea.
Compressing Slurry -was- Insulation Value
Posted by: "slurryguy" slurryguy@yahoo.com slurryguy
Date: Mon Aug 13, 2007 12:21 pm ((PDT))
Compressing slurry can take many forms. Following are a few ideas.
NONE OF WHICH I'VE TRIED AT A PRODUCTION SCALE. I've played with all
these concepts successfully on a SMALL SCALE. Experiment all you
want at your own risk. Be careful out there gang.
Compressing slurry to make blocks might be easiest. I envision a
contraption similar to the Cinva system for making compressed earth
or adobe blocks. Imagine if a cinva were built using a perforated
box? Water could easily drain out as the block is getting
compressed. Think of a big industrial strength potato ricer! (btw,
a regular potato ricer works really well for small scale
experiments. Make sure you clean it before returning it to the
kitchen or incur the wrath of the family cook!!! slurryguy claims no
responsibility for injuries resulting from flying cookware thrown by
angry cooks.) Several hundred psi seems reasonable in a block
press. It would also be easy to reclaim the water draining out of a
press and recycle it back into the next batch of slurry.
Compressing slurry in a block making slipform like Judith uses might
be as simple as laying some lumber across the top of the form just
covering the slurry, but not overlapping the form. The vehicle
towing the mixer might be driven over the top after some initial
draining, thereby compressing the mix into the form. I wonder if the
slurry might try to ooze out from under the sides of such a form, so
I'm not certain if this would work well. If someone tries it, please
be careful to not damage your vehicle. This concept may need to have
some bugs worked out to make it work.
Compressing slurry while slipforming would be more difficult, but
still could be done. Imagine someone were using a wall system
similar to the diagram posted in the photos section for a bailing
twine reinforced wall. With each lift of slurry poured into the
slipform, a box beam could be laid across the top of the slurry so
that it nests inside the slipform. Long strap clamps could be looped
over the wall and attached to the rebar staples embedded in the
foundation as shown in the diagram. The box beam would obviously be
removed before the next lift of slurry were poured.
Cast in place walls could be compressed in a similar manner to that
described for slipforming.
I cannot think of a good method to compress sprayed slurry. The
variables about the shape and location of the potential surfaces are
too many to wrap my feeble brain around.
--- In papercreters@yahoogroups.com, <bob@...> wrote:
>
> Good thinking- I like the thought process. If your form has a
trough on top
> with a water repellent barrier- then you could use water to
compress the
> slurry-more water more compression. What is water about 8 pounds to
the
> gallon? Bob C
>
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