[Cob] Alkaline soil

[jane at kirstinelund.dk]

>From what I, as an archaeologist, have learned about the use of different
kinds of clay for different purposes, alkaline clay is generally preferred
for building - if accessible. The lime will make the clay more water
resistant, and probably also stronger.

However, I do not know how high the lime content can be without causing
trouble (and it sounds like yours is very high), or if it might affect the
straw. Probably any weakening effect will counterbalanced by the
strengthening of the clay itself, but again - I suppose it depends on the
actual content.




> Hi,
>
>   We are considering building a cob house in SE Nevada.  Our soil is
> sand/silt with about 20% clay (non-expansive) and very little organic
> matter.  My concern is with the soil Ph.  We have what is apparently
> known as "free lime" soil; it is so alkaline that if you pour vinegar on
> a pile of dirt it will fizz like baking soda.  Does anyone have
> experience with this type of soil, or have any idea if it will effect
> the success of the cob walls?  Will the alkali break down the straw over
> time?  Any help and advice appreciated.
>
>   Thanks,
>   Christine
>
>
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-- 
Jane Mondrup
Bjedstrupvej 21
8660 Skanderborg
Tlf: (+45) 20 85 71 91