To my knowledge thermal conductivity has nothing to do with thermal
heat
storage per se. I believe that the thermal heat capacity of the
material
is the parameter of interest when discusing a materials ability to
store
heat. As such I don't personally know of any additive that will
increase heat capacity in concrete without substantial ammounts of
the
stuff. Anyone else?
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To increase the heat capacity, you need the right aggregate. Most of
these would in fact be high magnesium minerals such as olivine or
soapstone (perhaps talc also). Soapstone, for example has 4 times the
conductivity of concrete, about 120% the specific heat, and 120% the
density (of standard aggregates). So - it depends on what you've got
available locally - there's olivine aggregate available in north
western North Carolina and north western Washington, for example. There
is no magic bullet to my knowledge that you would just sprinkle in the
mix. Only other thing I can think of would be to use a lot of steel :-)
--
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Norbert Senf email: mheat@mha-net.org
Masonry Stove Builders mheat@hookup.net
RR 5, Shawville website: http://mha-net.org/msb
Quebec J0X 2Y0 fax: 819.647.6082
voice: 819.647.5092
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