[GSBN] use of ashes in clay plasters and/or floors

[Norbert Senf]

At 01:57 PM 2/5/2009 -0500, Rob Tom wrote:
>(snip)
>The ASHRAE Handbook of Fundamentals lists the thermal conductivity of wood
>ashes as being
>
>     0.041 Btu/hr*ft*degree (Fahrenheit) @ mass density of 40 lbs/ft^3
>(snip)
>
>dry packed earth (@ 90 lbs/ft^3 density)  = 0.037
>(snip)

Hi Rob:

I don't have a whole lot to add, my speculation would be along the same
lines as yours. I think the big clue, however, is that your data, above,
shows that the conductivity of ashes is HIGHER than dry packed earth.
In other words, the insulation value is lower.

Best ........ Norbert

>Oficial-looking numbers aside, my gut tells me that ashes wouldn't do much
>towards providing any insulation value to a clay floor, either if mixed
>with the clay or configured as a separate layer underneath the clay.
>
>
>Why ? Because my guess is that any insulating value that ashes my have is
>probably due to trapped air in the interstices between the ash particles
>and when compacted (as would be the case in a floor construction, most of
>those air pockets would likley be gone.
>
>The other thing is that ashes seem to suck up water quite readily and when
>a materialis water-logged, it becomes a better thermal conductor than
>insulator.
>
>But all this is just speculation on my part. I've copied Norbert Senf on
>this message and my guess is that he'd know more factual info.

-------------------------------------------
Norbert Senf---------- mheat(at)heatkit.com
Masonry Stove Builders
25 Brouse Rd.
RR 5, Shawville------- www.heatkit.com
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