For most bases, the recommended 3000psi mix will work just fine. Regarding
the hole, I found that the local sign company had augers up to 4 feet in
diameter. To get an equivalent to a 3 foot square hole, drill it out with
the 36inch auger. The wobble in most soils will get the desired hole for
volume of concrete.
73s, Ron K0RL
----- Original Message -----
To: <email@example.com>; <firstname.lastname@example.org>
Sent: Monday, March 19, 2001 10:52 PM
Subject: Re: [TowerTalk] Concrete Strength
> In a message dated 3/19/01 2:18:48 PM Pacific Standard Time,
> email@example.com writes:
> > I am putting up a US Tower TX-455 in about 4-6 weeks. When I priced the
> > concrete delivery, the first question was; "What strength do you want?"
> > Examples given were 1500 lb., 2000 lb., etc. I asked a US Tower
> > representative, but they didn't know. Any recommendations from the
> > would greatly be appreciated.
> Okay, concrete. According to the US Tower Foundation Notes - General,
> calls for "minimum compressive strength of 3,000 psi @ 28 days". This is
> pretty a typical contractor-type mix. On the foundation drawing notes it
> calls for 2500 psi. Take your pick.
> Here's something that I'm trying to change in regard to US Tower
> installations. It's almost impossible to dig some of the holes that are on
> their drawings and in their catalog. For example, your tower in the
> calls for a 3' x3' x 6'6" deep hole. This is impossible for a backhoe to
> There's not enough room to articulate the bucket and do the excavation.
> can't dig it by hand; not only is it dangerous but also there's not enough
> room to use a shovel. I don't think anyone from UST has actually installed
> one of these bases - it's really a stupid design. My advice is to get an
> engineer to design a more "practical" configuration.
> I always try to get the anchor bolts and base fixture sent a month or
> ahead of the tower delivery so that you can install them and allow a
> of weeks for concrete curing. Then when the tower arrives, you have a
> boomtruck or backhoe meet the truck and unload the tower and then carry
> tower over to the base and drop it in place. This way you only have to
> the boomtruck/backhoe to show up once instead of twice.
> You can either make a wood template to hold the anchor bolts in place
> while you're pouring or weld them together with some rebar. In both cases,
> you're trying to hold the anchor rods in the proper alignment during the
> pour. Either tie the rods to the rebar cage or space it above the forms
> a 2x4 under the base fixture.
> It's a bunch of work but it'll be worth it. Drop me a line if you've
> any more questions - I've installed a number of these and other towers.
> Cheers, Steve K7LXC
> Tower Tech
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