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I am installing 9 new street signs on poles as soon as they arrive from the custom sign company. The poles are aluminum and the holes are going to be 12" in diameter and 24" deep. I would like to pour a round base at the top of the hole, at the base of the pole which will be 18" in diameter and a total of 12" tall, 9" of the height sticking out of the hole.

The base is to protect the pole from lawn mowers, grass trimmers, etc. I would like the edges of the base to be smooth finished obviously as well as the top of the base. Wondering what others suggest I use for a form to get the smooth finish.

I thought about cutting 5 gallon bucket and using the plastic for a form so the sides would be fairly smooth. But there are 9 sign posts, so that would be a lot plastic buckets and cutting........

The round cement form tubes are also another possibility and would be easier to cut. I don't know how easy the tubes remove once the cement sets up. Also, how smooth would the sides of the cement in the tubes be or would they be porous because of the cement not being finished in the sides of the tube. I am not sure if they make those cement tubes 18" in diameter, as most I have seen are 12" in diameter or smaller.

So looking for ideas and suggestions for the forms. I don't want to pour the entire hole 18" in diameter as I don't need that much cement in the hole for the post and should the pole need to be removed, I don't want to need a crane to get it out of the ground.....

The posts are fluted and made of aluminum and powder coated. I thought about inserting a PVC sleeve in the ground around which to pour the cement and then having the sleeve stick up about 2" above the 18" round base. Then, I could drill the sign post and the PVC tube and use a stainless spring pin to hold the post in place so it doesn't rotate inside the PVC sleeve. If I need to replace the pole or pull it for repairs, etc. it would be much easier than having the post anchored directly in the cement.

The base of the poles have cast accent pieces which are about 18" tall that slide over the pole and are secured with a stainless set screw. This way, the pin and the plastic sleeve would actually be underneath the removable base cover piece and not visible. Just wondering what others think of the PVC sleeve idea instead of directly cementing the pole in. As long as the poles fit snugly inside the PVC so it doesn't "wobble", I can't think of any downsides to the sleeve idea.

The poles are 12' long and the signs and details have to added when the pole is set in the ground. The poles are drilled and tapped for mounting the signs, instead of using any clamps, band straps or external fasteners. With the sleeve, I could assemble the sign poles completely and position them in the sleeve and pin them in place and then slide the cast base cover piece over the retention pin and secure it with the stainless set screws. It would be easier than cementing the sign post in place and then having to assemble the signs onto the top of the post working off a ladder..........Plus if the poles get damaged it would be easier to replace them.

Thoughts on the best forms to get a smooth finish on the sides of the concrete? Also which forms will be easier to remove from the cement and give me the best end product?

I thought about other shapes for the bases but if there are any edges on them they will chip from the mower decks over time and look terrible. Round bases eliminate the edges and hopefully look nice longer.

Thanks for suggestions and tips............
 

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Plastic buckets cut easily with a circular saw or saws-all. You can probably get them for free from a restaurant or grocery store if you ask.

Another possibility would be to use 1/4” plywood 75 1/2” long (pi multiplied by diameter for circumference of circle) and make a form. You would need to stake it down fairly well to make it stay together.

As far as the sleeve idea goes, I’d be concerned about the pvc cracking and then would be a loose fit. Maybe sink a shorter section of post in the concrete with about a foot sticking out that you could bolt the sign post on to?
 

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Hello SB, i was going to suggest sonic tube too. Lowes and HD usually have it in stock. Works great and used on commercial and residential construction sites.

Good luck!
WB
 

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I would use sonotubes, and wet them down before you pour, so the cardboard doesn't soak the water out of the concrete. That will help to have a nice finish around the edge. If it is critical to have a nice surface, you could rent a concrete vibrator for around the edges, or at least tap the edges very well to settle the concrete. You could also spray a release agent, or some sort of oil on the forms to help them release.

If you have frost, I wouldn't make it bigger on top than down below, the frost will eventually pull the whole thing out if it's bigger on top. With smooth sides all the way down, it won't pull it up.

I like the sleeve idea, but I think you'd be better off with a galvanized pipe or something other than pvc. The pvc will eventually get brittle and break off. You would still have the sleeve inside the concrete, but the stub may break off.

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They do offer Sonotubes, or other branded equivalents, in 24" diameters. I have utilized them for a number of projects and if you were closer, I have a 5' length of a 24" sitting in the garage that I would give you. (Where I source them, they are only offered in 10' lengths.)

The problem becomes making a step from 18" to 24" diameter, as you describe. Keeping it centered, square and level will be nearly, if not impossible, to do so. The other issue will be frost heaving. Pouring a larger diameter cap on top is going to give the frost something to lift against it. It will crack/bust loose in time. That is the reasoning concept behind a sonotube verses just utilizing a post hole auger to make a hole and fill it with concrete. You want a smooth, with no edges, footing so the frost soiled will slide past it as it heaves, rather than grabbing on to it.

For example, I utilized two 18" diameter, round, heavy wall plastic trash cans that I obtained at Walmart for the form tubes I utilized for my beach house balcony posts. We were only 30' from the shoreline and not much grade, so I was going to be in water at the base of the hole. I needed something that wouldn't come apart in the water, like a sonotube, and was enclosed to keep the water out. They were 36" tall and the top of the first was above the water level. I cut the top 24" off the second one to add to the first, taping them together with duct tape and gently backfilling. The last few winters, we've really had some frost heaves in front of the beach house. The soil will push up nearly 10" around the diameter of those trash can tube footings, making a perfectly round soil collar around the post. Thankfully, it all goes back down when the frost melts in the spring.

As far as providing a smooth exposed finish, you can add more water to the mix, but that comes at some risk with the long term durability of the concrete. The poor man's method is to vigorously run a shovel up/down in the freshly poured concrete, in the tube, to displace the air pockets. However, this is not fool proof. The big boys have vibrating rods, which are the cat's meow. You may be able to rent one.

You can peel off the sonotube, down to ground level, once the concrete has set. It is a bit of a job, but not impossible by any means.
 

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Elephants Foot

Have you ever heard of something called 'Elephant Foots'? So named because they resemble an elephants foot. They are shaped to taper from about 24" at the base to about 8" at the top in 2" increments. You can use it all or just portions of it so that it fits your needs. They make frost heave a lot less likely in areas that get frost. You cut the top off to fit your diameter of sonotube and fill it and the sonotube with concrete. If you didn't want it visible, I think that you could slice it off after the concrete sets. I don't know if it's the answer to your needs but it is something to consider. Good Luck.
 

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another possibility is ........to cut rings from 55gal metal drums ....and leave the form on when done ....this is similar to what you see at gas station islands they have a leave on metal form in most cases ...smooth paintable durable to impacts etc

of course sonotube as mentioned is a option (but its relatively expensive)

rings from plastic drums...30gal or 55gal

you can premake round form hoops from about anything flexible such as....1/4 plywood strips ...siding....sheet metal....but they will need to be shaped and staked during the pour

you can go to a corrugated culvert company (tin horns , whistles) and they sell the bands to connect two steel culverts together in each size (google culvert metal band coupler) ....they would either make a permanent or removable form since they are split on one side

plastic culvert pipe

just a few ideas...


if it were mine i would probably go the metal culvert way and just cut rings from the appropriate size and leave the form on since its galvanized and ribbed-(you see this type product in street signs in our area to protect concrete from right o way mowers)

to answer some more of your questions.....sonotubes come in all sizes they just get quite expensive in larger sizes and would probably not be available at lumber yard (talk to redimix concrete co)(cutting them to length is easy cutting them to remove is more difficult) i have seen persons precut them for removal and put a couple of rachet straps around them during pour to make them easier to remove ....also any removable form needs to have a release agent sprayed on it in the old days they would use diesel fuel (now illegal) but these days you can buy a water based product
 

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I would use 10" sono-tube for the form at the top. https://www.lowes.com/pd/QUIKRETE-Common-10-in-Actual-9-5-in-Quik-Tube-48-in-Concrete-Tube-Form/3018328

Down in the hole, if you are making your holes with an auger, there may be no need to form the bottom, just use the wall of the hole as the form and then fasten your top form so that it sticks below grade at least 6" and above grade whatever distance you want them to be above grade.

Concerning the PVC in the middle to put the post into. I would definitely do this. I would use a PVC that is at least 2" bigger than you sign post and when installing, insert the sign pole, plumb it, hold it in place with pre-made wooden wedges and pack sand in between the PVC and the sign post. This is how flagpoles are installed and they are rock solid after getting the sand around the pole.

Below are some pictures that show how I formed for my flagpole footer. This is much more than you will need for sign poles but the concept of how I secured the above grade form to the ground will be the same.

I wanted a modified square look on my above grade concrete so I made my forms. To do yours, you will just need to cut pieces of sono-tube long enough, screw 2 x 6 cross supports to the sono-tube so that the cross supports rest on the ground or a block of 2 x 6 and you will have to shim as need to make sure the sono-tube is plumb, and secure them from moving with grade stakes.

After that, I would take a piece of the correct size PVC, drill a hole centered in a PVC cap, install an approx. 3" long full thread length bolt sticking outward into the cap, then put the cap on the end of the PVC. The bolt sticking out the lower side of the cap will be driven into the ground so that it is centered in the sono-tube. make sure the PVC is a couple inches longer than the top of the sono-tube so that it sticks our the top.

Screw some fairly substantial screws into the cross braces so that the head is about 3" above the top surface of the sono-tube, take mechanics wire and cross tie the PVC in place with wire so that it is held securely centered in the sono-tube. When ready to pour, the wire holding the top of the PVC should be about 2" - 3" above the top finished surface of the concrete (this was the purpose of using long screws that are strong enough to take the leverage applied).

I've included some pictures below of how I formed my flagpole base.
 

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I would use 10" sono-tube for the form at the top. https://www.lowes.com/pd/QUIKRETE-Common-10-in-Actual-9-5-in-Quik-Tube-48-in-Concrete-Tube-Form/3018328

Down in the hole, if you are making your holes with an auger, there may be no need to form the bottom, just use the wall of the hole as the form and then fasten your top form so that it sticks below grade at least 6" and above grade whatever distance you want them to be above grade.

Concerning the PVC in the middle to put the post into. I would definitely do this. I would use a PVC that is at least 2" bigger than you sign post and when installing, insert the sign pole, plumb it, hold it in place with pre-made wooden wedges and pack sand in between the PVC and the sign post. This is how flagpoles are installed and they are rock solid after getting the sand around the pole.

Below are some pictures that show how I formed for my flagpole footer. This is much more than you will need for sign poles but the concept of how I secured the above grade form to the ground will be the same.

I wanted a modified square look on my above grade concrete so I made my forms. To do yours, you will just need to cut pieces of sono-tube long enough, screw 2 x 6 cross supports to the sono-tube so that the cross supports rest on the ground or a block of 2 x 6 and you will have to shim as need to make sure the sono-tube is plumb, and secure them from moving with grade stakes.

After that, I would take a piece of the correct size PVC, drill a hole centered in a PVC cap, install an approx. 3" long full thread length bolt sticking outward into the cap, then put the cap on the end of the PVC. The bolt sticking out the lower side of the cap will be driven into the ground so that it is centered in the sono-tube. make sure the PVC is a couple inches longer than the top of the sono-tube so that it sticks our the top.

Screw some fairly substantial screws into the cross braces so that the head is about 3" above the top surface of the sono-tube, take mechanics wire and cross tie the PVC in place with wire so that it is held securely centered in the sono-tube. When ready to pour, the wire holding the top of the PVC should be about 2" - 3" above the top finished surface of the concrete (this was the purpose of using long screws that are strong enough to take the leverage applied).

I've included some pictures below of how I formed my flagpole base.

like to see good craftmanship and pride in work.......all the bevel cutting on the form boards was a bit over the top though :) (most concrete guys would have built a square box H shaped long legs spanning the hole and cut styrofoam or wood inserts in the corners) ....love the result ...and the purpose...:bigthumb:
 

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I would use 10" sono-tube for the form at the top. https://www.lowes.com/pd/QUIKRETE-Common-10-in-Actual-9-5-in-Quik-Tube-48-in-Concrete-Tube-Form/3018328

Down in the hole, if you are making your holes with an auger, there may be no need to form the bottom, just use the wall of the hole as the form and then fasten your top form so that it sticks below grade at least 6" and above grade whatever distance you want them to be above grade.

Concerning the PVC in the middle to put the post into. I would definitely do this. I would use a PVC that is at least 2" bigger than you sign post and when installing, insert the sign pole, plumb it, hold it in place with pre-made wooden wedges and pack sand in between the PVC and the sign post. This is how flagpoles are installed and they are rock solid after getting the sand around the pole.

Below are some pictures that show how I formed for my flagpole footer. This is much more than you will need for sign poles but the concept of how I secured the above grade form to the ground will be the same.

I wanted a modified square look on my above grade concrete so I made my forms. To do yours, you will just need to cut pieces of sono-tube long enough, screw 2 x 6 cross supports to the sono-tube so that the cross supports rest on the ground or a block of 2 x 6 and you will have to shim as need to make sure the sono-tube is plumb, and secure them from moving with grade stakes.

After that, I would take a piece of the correct size PVC, drill a hole centered in a PVC cap, install an approx. 3" long full thread length bolt sticking outward into the cap, then put the cap on the end of the PVC. The bolt sticking out the lower side of the cap will be driven into the ground so that it is centered in the sono-tube. make sure the PVC is a couple inches longer than the top of the sono-tube so that it sticks our the top.

Screw some fairly substantial screws into the cross braces so that the head is about 3" above the top surface of the sono-tube, take mechanics wire and cross tie the PVC in place with wire so that it is held securely centered in the sono-tube. When ready to pour, the wire holding the top of the PVC should be about 2" - 3" above the top finished surface of the concrete (this was the purpose of using long screws that are strong enough to take the leverage applied).

I've included some pictures below of how I formed my flagpole base.
Nice workmanship. How are you are addressing the water that will find its way into the electrical boxes and conduit?
 

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What about aluminum flashing?? I bought a big roll for a project,, it was reasonable in price,,
oil it with used motor oil, just before pouring,, if it is level,, it WILL be round,,

put a few screws in it,, the aluminum will be easy to remove,,,
 

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Thanks for all the suggestions, I have gotten a bunch of good information and ideas.........:good2:

I was going to mention in my original post that I verified that I did not need to use the "Break away" sign post bases to comply with the law. Despite the fact these signs are on private roads, they still are subject to ALL of the sign rules and regulations. Technically, since you "invite" the public into the neighborhood when you call the Domino's Delivery driver (who was just at my house....) and the trash truck picks up the trash, and UPS and Fed Ex delivery packages, etc., etc. you have to comply with the sign code for placement, size, reflectivity, fonts, sign size, you name it.

Actually, the sign laws are kind of interesting, the street signs have to have letters with a specific grade of reflectivity and the letters have to be a specific size based upon the traffic speed. A combination of Upper and Lower case letters are now required under Federal Statute and signs with all the same case no longer qualify for use after February of this year. There are very specific rules about how high off the surface the signs are supposed to be.

I am glad I didn't have to use the break away bases for a couple of reasons, they are ugly on the base of the poles and since there is so much emphasis on making these sign posts look as nice as possible, I wanted to avoid the "Ugly" break away base. Keep in mind that every one of these sign posts is in someone's front yard, verses the signs you pass at 55 mph or 70mph on the highways...

The second reason is the break away bases cost nearly $500 per pole........which would nearly double the entire cost of the project. Also, when struck, the pole will fall completely over, damaging all the signs on top, which are expensive. Our speed limit is 20 mph so if some one hits a pole, they will damage the pole and probably the car but unlike to knock over the entire pole and destroy the signs, which are custom made.....If they do, they better hope they have insurance or some spare cash........:laugh:
 

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Sonotubes have a heavy wax coating inside them to make removal easier. You still have to cut a slot with a utility knife to start the removal process; but then they generally peel off. You could always brush on some old engine oil if you want more mold release on the tubes.

As another poster said; you can get sizes above 12"; but you generally have to go to a real building materials supplier instead of the big box store. I bought some 21" diameter tubes a few years back for my front walkway bollard light project. They even cut them to the length I needed on their purpose built Sonotube cutting machine.

If you do the 18" diameter pier-cap over a 12" diameter pier; you might put down some rock or pea-gravel between the pier-cap and native soil that can displace itself during frost season.
 

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Nice workmanship. How are you are addressing the water that will find its way into the electrical boxes and conduit?
Careful sealing of every box. haha!!
Actually, the electrical boxes are above the top of the concrete 1/2" so surface water will not get into the boxes. The electrical box caps are watertight and the two that I have my lights mounted in, the light connectors are watertight seals plus I added clear silicone to all the seals for an extra measure of waterproofness.

The lights that I used for this project and extreme quality lights made by Kichler. They are Kichler 15731 Low voltage LED lights with a 10 degree beam angle designed to illuminate flags.
 

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The problem becomes making a step from 18" to 24" diameter, as you describe. Keeping it centered, square and level will be nearly, if not impossible, to do so. The other issue will be frost heaving. Pouring a larger diameter cap on top is going to give the frost something to lift against it. It will crack/bust loose in time. That is the reasoning concept behind a sonotube verses just utilizing a post hole auger to make a hole and fill it with concrete. You want a smooth, with no edges, footing so the frost soiled will slide past it as it heaves, rather than grabbing on to it.
When I use Sonotube (Concrete Tube Form) I always pour a foundation in the bottom of the hole a couple days prior to pouring the tube.
The poured foundation will self level.
https://www.greentractortalk.com/forums/home-workshop-projects/14700-pole-barn-work-3.html#post146697
 
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