[TowerTalk] Using old concrete in new pour

[Michael OBrien]

When time came to pour the base for my self-supporting HDX-555 several years ago, an argument erupted with the concrete truck driver when he delivered "soupy" mix that failed the "slump test" specified by US Tower.

I had hired out the digging of the base hole and the construction of the rebar cage. My contractor hadn't worked on a tower project before but had done other excellent work for me. He was scrupulous in studying the engineering specs and following the manufacturer's instructions. I overheard him ordering the concrete and being very specific about the required consistency. When it arrived "soupy" and the driver scoffed at his objections, my contractor called the concrete company manager, reminded him of the details of the order and said we were rejecting this delivery. The manager wasn't thrilled but he agreed. The pour was delayed a day but, as someone who knows only a little about construction materials, I was grateful that my contractor rejected the driver's insistence that "concrete is concrete" and had insisted upon following the manufacturer's recommendations.

Does your tower manufacturer's instructions mention a "slump test"? 

73,
Mike K0MYW





On Tuesday, October 21, 2014 9:00 PM, "john at kk9a.com" <john at kk9a.com> wrote:
 


One concern is if you are making the concrete "soupy" by adding extra water
it becomes less strong.  A 30' aluminum tower has a small concrete base so
why not play it safe and use the proper mixture?

John KK9A


To:    "towertalk at contesting.com" <towertalk at contesting.com>
Subject:    [TowerTalk] Using old concrete in new pour
From:    David Gallatin via TowerTalk <towertalk at contesting.com>
Reply-to:    David Gallatin <kc9eev at yahoo.com>
Date:    Tue, 21 Oct 2014 16:53:26 -0700
List-post:    <towertalk at contesting.com">mailto:towertalk at contesting.com>
Hello everyone,
A ham friend today suggested using concrete from an old pad that's broken
into 
small (maybe fist size or a bit smaller) pieces and using it in
a new pour, specifically for my new 30 foot aluminum tower. He said you make

the new mix "a little soupy" and toss the old chunks in as you go, the idea 
being less new concrete is used (and paid for) and when it dries you can't
tell 
a difference "concrete being concrete". He did not specify what kind of
ratio 
of old to new is used but he does have two pads of his own he has done this 
with that hold 60' steel self supporting towers. 
I have tried to research this and come up with nothing. I did find reference
to 
concrete being recycled (crushed) into aggregate size and used as such in
new 
pours but what he is talking about does not seem to be the same thing. 

Obviously I am a tad concerned about doing this. Has anyone heard of this 
technique before?

73, 
David, AA9G

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