An earlier post included information from Hank Lonberg, P.E./ S.E., KR7X that
rebar. Among many points Mr. Lonberg made, ASTM A 706 is a weldable
reinforcing bar. A major
redi-mix firm near here stocked it. I found it easy to weld with E7018
electrodes. I designed a
rebar structure that provided both the reinforcing required for my tower base
and complied with
the requirements for a Ufer ground. It was very easy to lower that welded
assembly into the
hole with the loader on my tractor. Alternatively, I believe two persons could
it into the hole.
Good welds ensure low resistance connections among the members, which is
essential for the
Ufer cage and any connections from it to the outside.
Another point that should be observed in building a tower base:
It is important that no steel penetrate the concrete below grade. A
penetration provides a path
for the natural alkalinity of concrete to leach out, thus losing some of the
protection that concrete provides to steel. Bring grounding terminals out of
the concrete above
grade. To prevent penetration, place concrete "pills" at least 3" thick under
the steel at the
bottom before pouring the concrete.
An easy way to level the bottom of the hole for those pills is with limestone
a crushed limestone supplier. In this area, the screenings are sold for about
1/2 the price
of road rock. They level easily and pack firmly with very little tamping.
73 de WOØW
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