[TowerTalk] ground rods and angle...

[jimlux]

On 1/20/16 3:53 AM, Roger (K8RI) on TT wrote:
> I have trouble understanding Bentonite needing to be "recharged"  I
> believe it's a form of clay that is relatively conductive?. Isn't
> Bentonite also the material where you drill holes in concrete, pour in
> dry Bentonite, add water and it slowly expands to break the concrete?
>

Yes..

These kinds of clays in general, and bentonite and its friends in 
particular, are interesting.

Fuller's earth is another form of bentonite (or similar clays) and is 
used in the processing and cleaning of cloth, and in the special effects 
business to make a safe(ish) dust cloud and to make things look dusty. 
It's used in spot removal, as an adsorbent along with a solvent (like 
the commercial K2R, which uses silica, but same idea)

They form a non-newtonian fluid when mixed with water - the viscosity 
changes with stress: like some milkshakes and ketchup - as the stress 
increases, the viscosity goes down (it's thixotropic), so you can pump 
it, but when it sits, it gets solid.  Hence, used for drilling mud. 
(given the drop in oil prices recently, the demand for mud has probably 
gone down, so prices might have dropped - buy your Bentonite now)

They're also expansive (not good if it's the stuff under your 
foundation). And, as Roger notes, they can be used to split concrete.

They're fairly common. Wikipedia has a decent description of where they 
come from and their properties.