Several posts recently have referenced slipforming.
I'm not sure where my following thoughts fit in to the discussion, so
I'll offer them as a separate topic. Feel free to bash them and pick
them apart.
I've been thinking and looking at a variety of different techniques
for working with papercrete and I keep coming back to something I am
going to call Sideslipforming.
"Slipforming" does not have to have forms that slide UPWARD. The
forms can slide in any direction. In almost every case where
slipforming has been mentioned in this group, the forms are intended
to slide upward. I'd like to expand everyone's thoughts on the topic
and consider thinking in other directions.
I propose building very narrow forms that are the full height of the
finished wall. These forms could be made porous. A frame could
easily support expanded steel mesh covered by hail screen. The form
would need to be 3 sided. The exterior face of the wall, the
interior face of the wall, and one edge. A temporary 4'th side, the
other edge, would be required for the very first pour. The forms
would be held vertically plumb with temporary bracing.
I'll describe pouring a simple rectangular structure.
The first pour would use a 4 sided form. The forms would be firmly
attached to the floor platform or to the foundation wall. A simple
rectangular column of papercrete would then be poured inside. After
it initially drains, a beam could be placed across the top and strap
clamps or cable hoists could be looped over the top of the beam and
used to pull it down inside the form and compress the papercrete.
More papercrete could be added and compressed until the form is full
and tightly packed. Having the formwork extend above the finished
wall height would probably make the process go a little faster. The
compressing beam would squeeze downward until the finished height is
achieved.
Then ... wait. Wait until that papercrete is set and SELF
SUPPORTING! The papercrete need not be completely dry, but it must
be able to support itself.
Then the forms can be stripped off and temporary bracing should be
installed to prevent the papercrete column from tipping over in any
direction.
The forms would then be slid over and attached to the foundation
adjacent to the first papercrete pour. One open side of the form
would be filled by the existing first pour. Repeat the pouring
process compressing the new pour just like the first one.
Wait.
Repeat.
If 2 sets of forms are employed. You can work twice as fast around
the wall. You can expand in both directions on either side of the
initial pour.
I see a great number of advantages to working in this manner.
No constant fiddling with blocks. No turning them over, no stacking
and mortaring them together.
Some tarps along the ground and small pit with a pump should be able
to capture runoff water for recycling into the next papercrete batch.
The width of the formwork is variable. Ideally, it should be the
amount of papercrete that someone can easily fill in one day. If you
want to use more forms and work even faster, you can install more
slipforms adjacent to yesterday's pour that is still drying.
Using narrow forms should allow someone to pour a curved wall.
Any wall thickness can be accommodated.
Protecting the papercrete as it dries should be a lot easier. A very
small surface area is exposed and tarps can be draped over the
forms/walls when it rains. This should be a lot easier than trying
to cover an entire yard with tarps to cover a bunch of blocks when it
rains. I can even imagine using clear or black plastic and creating
a very long "pup tent" like structure that might act like a solar
greenhouse. If a fan is placed at one end of the tent, it may be an
excellent method for speeding the drying process. (always move the
air from the dry end of the wall toward the wettest end of the wall.)
If the forms are covered in wax they should easily separate from the
papercrete as it shrinks away from the form.
This technique lends itself well to the bailing twine reinforcement
technique I described some time back.
Credit where credit is due:
This idea blatantly steals bits and pieces from many other people's
ideas.
Some comes from standard concrete pouring techniques,
Tim Pye and Spaceman's experiences contributed.
ElfNori's perforated slipform idea.
Mikey Sklar's battery dome.
Strawbale wall tie down compression techniques.
and probably several other idea sources that I can't remember. My
apologies to anyone who I left out.
I encourage anyone to pick apart the idea and point out the flaws, or
at least the areas where I didn't explain it very well.
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