Hi everyone. Found this group while googling the use of paper in
concrete. Anyway, like the subject says I'm interested in using
papercrete for small scale modelling and sculpting. I haven't had much
luck with my test mixes so was wondering if anyone could tell me what
I'm doing wrong. And I'm very sorry for the long post.
At the moment I'm experimenting with thin corrugated cardboard as the
paper source. I get heaps of it from used "soft pack" wine casks and
such. The first test batch I tried - before finding this site - the
cardboard wasn't really pulped completely. It was basically just
soaked for several days and rubbed and kneaded with the hands until it
was the consistency of clay. Then I added about half it's volume of
cement, mixed and added a little more water until it was again almost
like a very soft clay. This mix was put in a plastic fast food
container and molded into a bowl like shape. It dried in a matter of
days, although wasn't very strong.
So after reading here and a couple of other sites, the next batch I
pulped the cardboard really well (like when making paper), added the
cement and mixed for a longer time. This mix was much more uniform.
Putting it in the plastic mold though, it seemed to be too watery. But
reading the excess water would just bleed out/evaporate I molded it
the same as the first time and soaked up any bleed water with paper
towels. Well this batch took much longer to dry enough to remove from
the mold, but it seemed better since it was more uniform etc. After
letting it cure for nearly 2 weeks, it seemed fairly strong. It
definitely had more compressive strength. But it just crumbles too
easily to be used for anything. If I break a bit off it looks and
feels like the cement hasn't even really set. It's more like paper
mache with dust in it than a concrete product. There's no way I'd
build a house with it :)
Since then I made another test batch. This time I added about the same
amount of water as the first batch, but put more cement in (about a
1:1 ratio with paper). However this time the cement didn't even seem
to set at all. When tapping it sounded like it should be dry enough to
remove from the mold, it just crumbled in my hands. Maybe too little
water?
I really don't know what is going on. I can make lightweight concrete
for sculpting using perlite mixes and stuff. But when trying with the
cardboard I fail. Could it be the cardboard has some additives which
prevent the cement setting properly? I expected the glue in it would
help bond but maybe not? I think I'll do a batch with newsprint and
see if it works better. But I'd like to use the cardboard since I can
get so much of it.
Any ideas what I'm doing wrong? I spoke to a neighbor that works at a
concrete pipe factory and he's not sure why it won't work. He said
maybe use a bonding agent to help. But I'm trying to use as few
additives as possible.
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