When I put in my UST HDX-555 some 20 years ago, I hired a contractor I knew to
dig the foundation with a backhoe and construct the rebar cage as per UST
instructions.
He also ordered the concrete. But when the truck arrived, he insisted upon
checking something that was new to me -- the "slump" of the concrete.
The driver wasn't happy about it, but (as I recall) they placed a hefty blob of
concrete on a slanted board and then timed its travel down the incline.
Whatever, the batch didn't pass the "slump" test.
After conferring with the company office by phone, the driver took that load of
concrete to another construction site. A different truck was dispatched, and
the concrete it delivered was judged to be acceptable, "slump"-wise.
I'm guessing that "slump" has something to do with how much moisture is in the
concrete mix. I had never before, and have never since, heard the term used.
But it was important to my contractor that day.
Mike K0MYW
On Monday, August 26, 2019, 2:26:10 PM CDT, Bob Shohet, KQ2M
<kq2m@kq2m.com> wrote:
Mac,
Thank you for noticing my error. It was not 20 sq. yds, it was 20 cubic yds.
That’s what I paid for and what I received. I actually used ~ 18.5 cubic yds
for the two tower bases and six guy anchor holes – the “extra” was what was
dumped in the depression at the edge of my driveway.
I don’t recall the size of the truck or if they had to make more than one trip,
but t was a HUGE truck.
For perspective, because of the boulders and other debris in several of the
holes, what would start out as a 3’ x 4’ x 4’ hole became more like 4’ x 5’ x
6’ as a removed boulder or piece of construction debris (steel cables,
sheetrock, broken piece of wood, barbed wire, etc.) would tear out a chunk of
the dirt wall and require re-straightening by the backhoe and enlarging the
hole in the process.
Bob, KQ2M
From: Mac
Sent: Monday, August 26, 2019 3:07 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Concrete
Humm ? a 20 Sq yd concrete truck .. ??
that's a very big and very heavy truck , more to the point, they don't
make emm that big ...
mac/mc w5mc
On 8/26/2019 1:15 PM, Bob Shohet, KQ2M wrote:
> I used a different method which I will mention here just it case it may be
> helpful for a TT reader.
>
> My qth is on irregular and jagged ledge – in some spots the ledge is at or
> just below the surface (like an iceberg) in other spots, as little as 1’
> away, the dirt extends down for 4’ or more feet. You can’t predict where it
> is; you can only dig and see where it actually lies.
>
> My house sits in a small “valley” about 10 – 15’ below the top of the ledge
> which starts less than 15’ from the ends of the house. Coming from the
> street down my driveway facing my house, you could almost imagine this as a
> “U” with the middle part of the “U” flat and very elongated.
>
> Both of my towers are on the top of the ledge with no way to get there other
> than to climb up at a very steep angle > 30 degrees. This made it impossible
> to get a large concrete truck, with 20’ sq yds of concrete, up to the tower
> base. And even if it made the first base, it could never get through the
> dense woods and over the boulders to get to the second base 110’ feet away.
> It was a challenge.
>
> I decided to hire an experienced person with a SMALL backhoe. We proceeded
> by having the large concrete truck drive to the base of the ledge, extend its
> concrete pouring chute to the top of the ledge and then pick up that chute
> and place it in the “scoop” of the small backhoe. (We had discovered that
> only a small backhoe could navigate the boulders and jagged ledge (although
> not without tearing and blowing out two backhoe tires in the process!)) The
> concrete truck then poured the concrete through the chute into the scoop of
> the backhoe filling it ~ 1/2 way. The chute was taken out and the backhoe
> proceeded VERY slowly with the sloshing concrete and then poured it into
> slowly and carefully into the tower base and guy anchor holes (already
> strengthened with a cage or rebar and metal ties – previously made by N1MM
> and myself). At each hole another employee of the concrete company worked
> with a concrete trowel, level and other tools to move and spread the concrete
> and level it properly. We repeated this process many times over a 2 1/2
> hour period so that we could fill in both tower bases and six guy anchor
> holes.
>
> It was a slow and painstaking process but it produced outstanding results.
> No concrete was lost or spilled, the concrete filled all the holes and spread
> and leveled beautifully and the highly complex and challenging terrain was
> overcome. We even had ~ 1 yard of concrete left over which I had them dump
> into a depression in the driveway over an underground stream and which
> successfully filled and stabilized a mini-sinkhole. :-)
>
> This was in 1998 and cost ~ $1,050 cash for all the concrete, delivery, labor
> and 1/2 hour of overtime. I had calculated that doing it all myself with
> renting a mixer, buying all the concrete mix, and other chemicals, would have
> cost at least $400 and consumed at least two full days. I’m not sure if it
> would even have been possible to get the mixer through the woods and over the
> boulders to the two tower bases, and guy anchor holes on the ledge in the
> forest, but I do know that the labor would have been backbreaking – probably
> almost as bad as the weeks of chainsawing that I had to do in order to clear
> the dense forest for the tower locations. I know that I would not have had
> results as good as having the professionals do it. There has been no issue
> with any of the concrete in the past 21 years.
>
> I would also add that the pros know the temperature range that the concrete
> will set best at as well as the chemical composition of the concrete to give
> the best “pour” and “set”. I certainly would not have known that. For that
> information and knowledge alone to ensure the safety and the longevity of my
> installations, it was worth every penny!
>
>
> 73
>
> Bob, KQ2M
>
>
> From: k7lxc--- via TowerTalk
> Sent: Monday, August 26, 2019 1:11 PM
> To: towertalk@contesting.com ; xdavid@cis-broadband.com
> Subject: Re: [TowerTalk] Concrete
>
>> What size is your tower base?? In my opinion, mixing your own for a
> typical tower base is not a cost effective undertaking unless you have some
> insurmountable access issue that prevents you from bringing in a mixer truck.
> I agree. I've poured dozens of tower bases and every base plan I've ever
>seen calls for 3kpsi concrete. The labor involved in buying, transporting,
>mixing and pouring a base yourself doesn't usually pencil out compared to
>having it delivered.
>
> And if there is an access issue, hire a line pump to get the mud in the
>hole. It'll pump up to 400 feet which should solve most problems.
>
> Cheers,Steve K7LXCTOWER TECH -Professional tower services for amateur and
> commercial
> _______________________________________________
>
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