"Art" wrote in message
...
Dave wrote:


TX hill country. Fractured limestone is immediately below the soil.
Only a rock bar and alot of sweat, or, a diamond tipped auger can cut it.
18" is typical depth for corner and tensioning posts on typical pasture
fence. Wood or steel posts.

Guess answers for this are kinda like gardening, depends on the
conditions... Sandy soil, clay, swamp, gravel, or rocky in your case.

I pre-mixed, wetter than usual, the concrete prior to pouring in the hole
with the post. Used rocks to stabilize the post during the pour, then
fine tuned the plumb after the pour. Set the corners first.
Dave

Why "wetter than usual"?

--
Art

Because I used rocks inside the holes to stabilize the posts before the
pour. Wetter concrete assured me I had complete concrete saturation around
and under those rocks. No cavitation due to too dry a mix for that
situation. I used the inverted mushroom hole type. No gravel on bottom.

Stabilized bottom with suitably sized rocks, then top allowing at least 2"
above that topmost rock to concrete surface. Used level for plumb both
ways.

After the pour, I re-checked plumb and made minor adjustments if needed.

I did the tensioning posts similarly, except, I used a 3/4" offset
stringline for alignment with corners bottom and top. Stringline used for
rough, removed, then installed again after pour for final alignment. Of
course, the 90 degree opposite direction plumb was with a level.

A few neighbors in the area said to go with 5000 psi bagged concrete instead
of the 3000 psi version. They said they had no cracking problems with it
over time. Makes sense as sometimes 2 feet or more of the limestone rocks
will displace when using a rock pick or auger at the surface. Leaving
bigger area (hole) at surface to pour. Can't be helped. So, I used that
instead.
Dave