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freeze-resistant ceramics, last thoughts for now

updated thu 25 jan 07

 

stephani stephenson on tue 23 jan 07


one more thing
I don't doubt the Randal/cushing/insight coefficient
but here's where i have trouble visualizing or
truly understanding the thinking behind it...here's
the scenario i picture:


if you soak a fired clay bar in room temperature
water... the water gets into all the spaces and pores
that it can get into.

when you boil the clay bar in water, the hot water
(perhaps turning to steam ?), gets into even MORE
'pores' or 'capillaries'. we know this because the wet
weight is even higher in the boiling water test, more
water is taken in by the bar then when it was simply
soaked in room temperature water.

so, in my cartoon mind , i visualize the boiling
water, with less surface tension and/or turning to
vapor, penetrating into even tinier pores or
capillaries, that the cooler water couldn't fit into..

OK I buy that
but can someone explain this to me.
when i read cushing's and Insight's articles
describing the 'saturation coefficient'
they seem to imply that if you have a
bar of clay, which is saturated to the gills with
water, room temp water, cold water, rain water....i.e.
liquid water

the only pore space left is that tiny pore space which
only boiling water could squeeze into (the word
squeeze used only for visual purpose here!)

so if room temperature water, and certainly cold water
couldn't fit into that tiny pore space, how the heck
would it accomodate
freezing water and the roughly 10% expansion of water
in its frozen state?????

ice is less dense than liquid water but ice expands
...how could ice 'expand' into the tiny pores that
even the room temp water couldn't get to? i may be
missing something key here and i would LOVE to know
what makes this "c/b ratio or 'saturation coefficent'
work!!!

also i have seen it referenced in the following site
with regard to freeze thaw and brick... so there's
definitely some basis for it
URL
a http://www.bia.org/BIA/technotes/t2.htm


so i wonder if some other dynamic is at work
and....yes the thought that the strength of the body
matters yes! and maybe the capillary system merely
allows or encourages the ice to expand back out toward
toward the surface? certainly the design of the work
is a huge factor(allowing for runoff, expansion...as
well as the claybody itself

(like a charging javelina...it takes the path of
least resistance!)


Steph... must think about other things now :)



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