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Author Topic: POURING CONCRETE for Tower Base - suggestions?  (Read 9730 times)
WB8YQJ
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« on: August 15, 2010, 03:08:55 PM »

We have a 3 foot deep by 30 inch by 30 inch hole dug for the 30 foot tower. We need 12 inches above the grade (ground level) because the base is 48 inches high. Can anyone comment on the merits of buying readymix concrete from Home Depot and mixing this in a wheel barrow as compared to ordering out for concrete from a commercial company? Also looking for photos, anyone that might have used some wood to build up a box, about a foot above the hole in the ground. Seems simple and hard to goof, but still I'll ask here to avoid possible common problems. tia. Don.
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N4NYY
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« Reply #1 on: August 15, 2010, 03:12:34 PM »

I just paid the $300 or so that I needed for the 3 foot cube pour that I had. That was about 1 yard of concrete. When I did the math, I would have saved maybe $50-100 if I got the bags and did it myself. However, I figured it would take dozens of 80lb bags to equal 1 yard, and the labor would have been exhausting, and not worth it. The pours took a few minutes. Within 1 hour, all the work was done.

« Last Edit: August 15, 2010, 03:56:13 PM by Vinnie Sallustio » Logged
KZ1X
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« Reply #2 on: August 15, 2010, 03:49:20 PM »

More than a yard and I'd really question the 'savings.'

The consistency of the mix and the continuous pour capability of the commercial source is so much better than what one can do 'by hand' ... also, if the concrete company knows the application, they can adjust their mix for many variables that might be better for a tower base than the generic 'fill' specs on the bagged concrete mix.
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W5CBO
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« Reply #3 on: August 15, 2010, 05:00:28 PM »

I just put up two towers and checked out the DIY method and you'll need approximately 41 bags of 80 lb sakcrete to equal one yard.

In these parts an 80 lb bag goes for around $4.00 from Lowes so that's around $164.00 plus the cost of a mixer and a lot of back breaking work. If you're putting in rebar and gravel you can add that into the overall cost.

A local concrete company charged me $88.00/yd to come out and pour two tower base holes and 7 guy wire anchor holes which cost me around $1100.00 and it was done in around 20 minutes as he had to reposition the truck numerous times to pour each hole.

It's quicker and so much easier as well as cost effective to have it poured if you have room to have a truck to get into your property.
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K0IZ
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« Reply #4 on: August 15, 2010, 05:01:03 PM »

Standard bag is about 0.7 cu ft.  27 cu ft per yard.   However I did a somewhat larger pour without problems on a solar panel post.  Perhaps decision would be how easy the access for a truck?  Also there are sources for you-haul 1cu yd and less little trailers that could be an alternative.
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KE4JOY
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« Reply #5 on: August 15, 2010, 05:03:31 PM »

With the truck you have a much better chance at a monolithic pour.

Much stronger.
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N8EKT
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« Reply #6 on: August 15, 2010, 05:17:56 PM »

You have gone way overboard on the concrete for such a small tower but that being said,
the cost of bags vs getting a concrete truck is a no brainer.

It would cost a fortune to fill that hole with bags

Concrete calculators are available online that will easily show the difference
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AA4PB
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« Reply #7 on: August 15, 2010, 05:35:18 PM »

The minimum order on a concrete truck is way more than you need. Unless you can work a deal with someone who is working on a nearby job and can deliver some to you and then the rest of the truck to the other job, you are going to pay a whole lot for wasted concrete.

On the other hand it takes a lot of bags of sacrete for your job. I've done it and it worked out okay but here are some suggestions: Have plenty of help. Once you start the job you have to keep mixing and pouring until the job is finished so that it doesn't begin to harden during the job. I'd say a minimum of three people. One running the bags to the site, one doing the mixing, and one doing the pouring. They can rotate jobs. Watch the weather. You don't want to be working on a metal tower in a lightning storm and you can't stop mixing.

In some areas you can rent a trailer full of mixed concrete and haul it to the site yourself. I friend of mine did that and got stuck in traffic and wound up with a trailer of hardened concrete which had to be broken up with a jack hammer  Cry  Don't plan to haul it too far.

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N4JTE
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« Reply #8 on: August 15, 2010, 05:54:44 PM »

Call the nearest concrete yard and request to be put on a " short load" list and they will call you if they have some excess from a nearby pour. Mixing a yard and half of sackrete and pouring monolithically will take too long and unless you vibrate correctly, impossible with bag mix, you will never achieve the 3500 psi usually required for design specs. Sackrete is cheap for a reason !
Bob
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AA4PB
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« Reply #9 on: August 15, 2010, 06:29:28 PM »

I would disagree with any thought that you *can't* use sacrete safely. I've used it for a couple of Rohn 25 bases and not had a problem. The latest tower has been standing for 25 years now with no issues. Of course I can't tell you if it meets the 3500 psi requirement, but it does support the tower and it hasn't cracked in 25 years. The tower has been through a couple of hurricanes and several bad ice storms that brought down trees in the area in that time.

There are several issues to consider. One, can you get the "short load"? Two, can the concrete truck get access to the tower base? Its going to cost a lot more if they have to wait around while someone hauls it in a wheel barrow to the tower site as they would have had to do in my case.

The best way you do it all depends on your particular circumstances.
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KN0V
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« Reply #10 on: August 15, 2010, 06:31:39 PM »

Go thru your local cement plant. Forget the sackrete idea. The truck can be in and out in a short period of time. From the dimensions you give, it looks like about a yard of cement. Why is 12 inches of the base going to be above ground?
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WB8YQJ
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« Reply #11 on: August 15, 2010, 08:39:46 PM »

Why is 12 inches of the base going to be above ground?

The tower is non-guyed, aluminum 30 feet. The  48 inches vertical.

Its about 40 feet from the driveway (cement truck) to the hole in the back yard, somehow I'll need to get the cement moved. I saw one neighbor was forming a patio, they ran a large hose through their front door and out the back. !
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K5CQB
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« Reply #12 on: August 15, 2010, 08:55:53 PM »

12" above ground seems like a lot but if it's on the tower specs or code requirement then that's that.  I poured a block about a year ago and was able to buy my own sand, gravel, cement AND a used gas powered mixer cheaper than what 80lb bags or delivered would have cost me and I got to keep the mixer, yaaay.  I gave myself an education on concrete and am satisfied that my mix is stronger than what I would've got from the store or the basic ready mix.  The ready mixes you get delivered aren't priced bad but what I figured out later is that they have a minimum amount to buy or charge.  I think the local place wanted to charge me for 4 yards minimum and an extra fee for however long they were here.

Check your local scrap yard for the rebar.  I found 3/4 inch rebar much cheaper than what I would have paid for 3/8 at the box stores.

The frame for the above ground part is just as simple as it sounds.  No frame underground, pour against solid earth.  Keep it covered from the sun and moist.  Let it cure for about 4 weeks before stacking tower sections on it.

GL,
Jim
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N2CJ
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« Reply #13 on: August 15, 2010, 09:59:13 PM »

Locally there are concrete trucks that can do small loads "on demand" of any quantity from less than a yard up to about 9 yards. I've used them many times and it's worth the money. There is no minimum order. They have dry mix on board and using a water tank they mix the concrete to your specs right on site. No extra to worry about, no hidden fees, no problem.

BTW I have a small mixer which I use for sidewalks and such. I use Quikrete 5000 (that's 5000 PSI) and I have never had a problem. The bags are available in 40, 60 & 80 lbs. so you can give your back a break by buying the small bags. I have loaded an entire pallet of Quikrete 5000 on my F250 pickup.
« Last Edit: August 15, 2010, 10:02:44 PM by Glenn M. Muller » Logged
KD8GEH
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« Reply #14 on: August 15, 2010, 10:33:08 PM »

My 2 cents, just put up a 45 footer.
Local company were not nice, 275.00 1 sq yard. No short load or end loads (left over from other jobs). Some will do it no worries. I found 60 lb bags on sale at Manards 1.99 bag and rented a mixer from true value for 25 bucks. It took me 4 hours of hard labor and 50 bags 5in above ground, so other that the hard labor it was quite a savings.  If I was rich I would pay the 275.00 Smiley

Good luck and 73

Dave  KD8GEH
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