[TowerTalk] UST HDX589 crank-up tower base on rock?

[K7fe@aol.com]

Les, I really think that you need a civil engineer who has a background with 
rock and towers.  Yours is 90 feet plus mast so "force times lever arm" may 
translate one pound of wind load to nearly 100 pounds at the base of your tower. 
 

1.  Just installing the tower hold down bolts in the rock may not be good 
enough even with an ASTM rated epoxy like Simpson.  
2.  The recommended PSI rating of cement for towers may exceed what your 
rocks provide, so you will need to determine what the rock PSI is by testing.
3.  Rock is a natural product and may not be uniform or have fracture flaws, 
especially if you are blasting nearby.
4.  A cement tower base is enclosed by an iron re-bar cage which applies 
compression that would not be available in natural rock, so the rock may need to 
be stronger than the recommended (six sack/yard) cement.
5.  Compose an e-mail to ALL of the commercial tower manufacturers you can 
find and perhaps one of them has experience with rock installations.

You have a wonderful tower that many would be envious of, don't risk damaging 
it or someone......obtain professional help.

73,
Terry, K7FE