My absorption tests of simple fully-cured papercrete sample show a
166% weight gain with a 60 minute submersion in water. All of this
absorbed water evaporated within 8 hours (while sitting in front of a
fan), and the papercrete is back to its original weight. Now, this
was a big surprise to me, I figured it would take days again for the
papercrete dry out. What this tells me, I think, is that the paper is
fairly well encapsulated, and the fibers are not absorbing much water,
that the water has wicked into the pores -- not the paper fiber itself
(which is the fuel source for the glow). Thus, the paper fiber
doesn't absorb much post-manufacture. So you might be able to skip
the glycol, PC sucks up pretty good on its own, different from a solid
piece of wood that needs a carrier vehicle, organic or inorganic, to
promote absorption.
BUT, the problem with surface post-manuf. applications is that the
core of the material might remain untreated (depending upon its
thickness). Nasty stuff like electrical short circuiting occurs in
the core, where you need fire glow-suppressant the most. Well, maybe
not the most, the surface is important, too. I guess they're both
crucial. The ideal IMHO is to get the PC prepared properly at the mix
stage, then you're certain it will be successful. Scraping away the
char from the sample test I showed pictures of, I was amazed that 1/8"
down there was good solid papercrete that seemed totally unfazed by
the 2000 degree torch. A perfect circle 1 1/2" in diameter and 1/8" deep.
I have a simple-papercrete sample, fully-cured, that has been
saturated with a given amount of boric acid/water mix. I made this
yesterday. Within a few seconds the sample totally absorbed the
liquid mix, to about 3/4" deep on the sample. I'll find some time to
check it out and share the find. Now, let's say you already have a PC
structure and want to post-treat for fire, at least on the surface .
Then spraying with the mix might be the only solution and better than
nothing.
What's the hitch? Finding a cheap source of boric acid.
--- In papercreters@yahoogroups.com, "Ernie Phelps" <eepjr24@...> wrote:
>
> --- In papercreters@yahoogroups.com, "mdumiller" <mdmiller1@> wrote:
> > This proof of concept is important for the code portion of this
> > work, since PC can't be used in a many construction situations if
> > there is no simple (cheap) way to totally fireproof it.
>
> Very interesting. I am wondering if the same would hold true if you
> were to form the block normally, then soak it afterward in a Bora-core
> type mixture (boric acid, borac and anti-freeze, properly dissolved).
> This is know to penetrate several inches into dry wood, even, so it
> should work.
>
> - Ernie
>
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