[TowerTalk] Pour Complete

Roger (K8RI) K8RI-on-TowerTalk at tm.net
Thu Sep 2 13:17:54 PDT 2010



On 9/2/2010 3:16 PM, k2qmf at juno.com wrote:
> Hello Anthony,
>
> I am not an expert on tower installation but
> I see two things that "could" be a problem.
>
> First, they say to pour concrete into a hole against
> undisturbed soil without a wood frame!!
Many times this is not an option.  My tower base was certainly 
undisturbed soil.  It took me two days to dig the hole, but the guy 
anchors required forms.   After digging the holes which looked good, I 
went out the next morning to find three quite wide and shallow holes.
So, I had to have them redug and made forms (4th row of photos down on 
http://www.rogerhalstead.com/ham_files/tower.htm )
It'd be better to rent some steel forms if you can find them and if you 
can handle them...they are heavy.  The problem with wood is the form is 
supposed to be removed. Wet and decaying wood is like grease and not at 
all a good idea to have on your tower base or guy anchors.  I made one 
mistake and that was to put the frame on the inside. Put it on the 
outside. Remember too that concrete is going to put tremendous pressure 
on that box. If not really sturdy it WILL come apart.

Once the concrete has set and achieved a reasonable cure, remove the 
form and back fill. My preference is to back fill with dirt and plenty 
of water to make a slurry, but again it depends on soil conditions. If 
the soil is unstable enough to require forms it is either dry and loose, 
or very wet. Using a slurry in dry and loose soil will give it some body 
and it's relatively easy to remove voids.  If OTOH the soil is wet and 
sloppy/swampy you are going to need a larger anchor than typical. Also 
do not use elevated guy anchors in swampy soil. In a few years after 
regular re tensioning you may find the pole pointing in line with the 
top set of guys. Back guying will help
> Your hole sure has disturbed soil on all four sides...
>
That surface would have been good enough to pour against although I'm 
not sure about the basement side and working in the hole.
> Second,  It seems to be too close to the house.
> If you have a basement the tower base could push
> against the basement wall causing it to cave in...
If it stood up to the pour it's likely to stand up to anything nature does.
I'm wondering how they removed the forms.

The only question I have other than the forms, is crowning the pour so 
water will not collect.
> Again, I am no expert in this area. Just my personal observations.

73

Roger (K8RI)
> 73,
> Ted  K2QMF
>
>
> On Thu, 2 Sep 2010 14:59:08 -0400 "Anthony J. Cioffi \(N2KI\)"
> <n2ki at amsat.org>  writes:
>> Let the curing begin!  All is done for now here.  That had to be some
>> of the hardest work I have done in a long while.  8.5
>> cubic yards of 4000psi concrete. Next step is to put together the
>> tower sections.  Probably over the weekend.  More pictures
>> on Picasa.
>>
>>
> http://picasaweb.google.com/109109461434829776230/N2KISTowerInstallation?
> authkey=Gv1sRgCKjzp8rAo7jNzwE&feat=directlink
>>
>>
>> Anthony - N2KI
>> 30MDG - 1187
>>   www.n2ki.com
>>
>>
>> -----Original Message-----
>> From: towertalk-bounces at contesting.com
>> [mailto:towertalk-bounces at contesting.com] On Behalf Of Anthony J.
>> Cioffi (N2KI)
>> Sent: Thursday, September 02, 2010 06:09
>> To: Tower Talk
>> Subject: Re: [TowerTalk] concrete testing
>>
>> Thank you for the suggestions.
>>
>> I called Advanced Testing in my area and got some information.
>> First, I checked the trustworthiness of the concrete company.
>> That checked out.  The technical person I spoke with had a lot
>> experience with concrete testing and curing.  A 4" slump and
>> no more for this job.  However, due to the very warm temperatures in
>> the north east, I should cover it with plastic to keep
>> the moisture from evaporating off the top.
>>
>> I will keep the group posted and post more pictures.
>>
>> Thanks.
>>
>> Anthony
>>
>>
>> -----Original Message-----
>> From: towertalk-bounces at contesting.com
>> [mailto:towertalk-bounces at contesting.com] On Behalf Of jimlux
>> Sent: Wednesday, September 01, 2010 09:30
>> To: Towertalk Reflector
>> Subject: [TowerTalk] concrete testing
>>
>> So you have your concrete delivered, test canisters filled.  You
>> wait
>> 28-30 days and have the canister tested and Whoops, it fails the
>> test.
>> What happens next?  I know that if it failed by a "little bit", most
>> of
>> us would just figure, heck, use as is, that's what design margin is
>> for.
>>
>> But realistically, say it was totally defective.  Is it demolish the
>>
>> (huge) cube o' concrete and send a bill to concrete vendor time?
>> (I'm
>> assuming the delivery contract says that if they don't deliver the
>> right
>> material, they're responsible)
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