Fellow owner builder talk was Cob and Bathrooms (fairly long

[Speireag Alden]

Sgrìobh Patrick Newberry:

>In my own work I try to maintain the 10  to 30 percent clay in my bag
>mixtures,
>but I have one arch I build way back when out of just sand filled bags and a
>cement plaster which  as been thru all kinds of rain, weather etc. I
>figure the
>sand doesn't absorb water so it seems to hold quite well. It isn't even
>sitting
>on a foundation. I did it for fun and it's just a decorative item in our
>driveway.  I have had earth bag walls collapse, but only with arches not
>plastered.

    The sand definitely absorbs water if there's any water in contact with 
it.  Sand will hold, and keep, quite a bit of water.  That's why you can't 
fill a rubble trench foundation with sand; you have to use stones large 
enough that there's no capillary action.

    That said, sand in the application you mention may be just fine; 
barring freezing or real saturation, I don't know that its characteristics 
would change that much.  However, I'm not a soils scientist.

    Just a caution for cobbers:  sand *will* wick water from one place to 
another, and it does heave when it freezes, unlike stones with no fines.

-Speireag.
0>>>>>>(---------------------
Speireag Alden, aka Joshua Macdonald Alden
Joshua.M.Alden.91 at alum.dartmouth.org
Usually found somewhere in the wilds of New Hampshire.
Nach sgrìobhaidh thugam 'sa Gàidhlig?