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[TowerTalk] Welding re-bar, preventing corrosion

To: TowerTalk <>
Subject: [TowerTalk] Welding re-bar, preventing corrosion
From: Red <>
Date: Fri, 07 Jul 2006 16:34:34 -0500
List-post: <>
An earlier post included information from Hank Lonberg, P.E./ S.E., KR7X that 
addressed welding 
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 
have lowered
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 
screenings from
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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