Drilling anchor holes into heavy duty concrete filled bollard posts

I would like to drill and anchor some U-channel sign posts to large concrete bollard posts using 3/8"rd. expansion bolts. I'm thinking this might save me a lot of time on some various prevailing wage jobs school jobs I will be doing. How would I do this? Could I grind or mill away the schedule 40 pipe wall and use a rotor hammer bit or rebar cutter bit to tap into the concrete inside? ... Or, maybe I can braze them to the posts or use some kind of cheap portable welder that doesn't need a gadzillion amps?

I would try to have the GC leave the bollards only filled to about 18 inches bellow the pipe opening. Then when you get there to install the signs just bring concrete and cut the post to length and concrete them in.

Existing bollard posts filled with concrete.

Just use stainless steel Bandit straping and strap the u channel to the bollard. We have done this for years and never had one come down.

Ugh what a pain..... Well what J said or just take a metal drill bit with a corded drill and drill the metal out then hammer drill into concrete. I actually think that (depending on the size of hammerdrill bit) you may be able to just hammer drill straight through the metal into the concrete and anchor bolt it that way... I'd at least give it a try that way. I'm not too sure about welding to galvanized either. I've tried and its not easy.

I have a Mag Drill with hollow core milling cutters to cut through the pipe, but the bits are very expensive,... don't think they would they would like chewing up 'any' concrete? I have the stainless steel strapping machine, but I don't think they would go for that, at least for what I'm charging them.

Bandit is expensive, but figure in the cost of the bits you will eat up and your time. You can strap a post to a bollard in about 5 minutes.

http://www.amazon.com/BLUEROCK-Tools-Concrete-Z-1WS-Corin… http://www.ohiopowertool.com/P-2223-milwaukee-diamond-cor… There is a couple small core drills on the websites. just giving ideas. maybe you have a drill you can buy a bit for.

Have you considered using a hammer drill to remove some concrete from the top of the bollard; maybe about 12" deep? Then concrete a post (u-channel) in the existing bollard? This would provide a much better looking finished job. I have used this method in the past to replace broken U-channel posts in bollards at a Wal-Mart. In those cases, I had to break up the concrete about 6 - 8 inches deep. I cleaned out the loose stuff by hand and cut off the broken U-channel to allow enough overlap to bolt the new post to the existing stub. The bolted splice was covered when I replaced the concrete. The process went amazingly fast. I was expecting it to take about 45 minutes. But, it was about 10 - 15 minutes to chip out / clean out the top of the bollard and then maybe 10 minutes to set the new post. You may need to go a little deeper into the top of the bollard for enough support of the new post if you don't have a U-channel stub to bolt to. Use an extra long hammer drill bit like you probably use to set parking bumpers. A chisel point bit also helps. You will need to allow the new concrete to set and dry out overnight (or a couple of days) before painting the top of the bollard.

Q-stripe wrote on Aug 12, 2015:Go to #9

Have you considered using a hammer drill to remove some concrete from the top of the bollard; maybe about 12" deep? Then concrete a post (u-channel) in the existing bollard? This would provide a much better looking finished job. I have used this method in the past to replace broken U-channel posts in bollards at a Wal-Mart. In those cases, I had to break up the concrete about 6 - 8 inches deep. I cleaned out the loose stuff by hand and cut off the broken U-channel to allow enough overlap to bolt the new post to the existing stub. The bolted splice was covered when I replaced the concrete. The process went amazingly fast. I was expecting it to take about 45 minutes. But, it was about 10 - 15 minutes to chip out / clean out the top of the bollard and then maybe 10 minutes to set the new post. You may need to go a little deeper into the top of the bollard for enough support of the new post if you don't have a U-channel stub to bolt to. Use an extra long hammer drill bit like you probably use to set parking bumpers. A chisel point bit also helps. You will need to allow the new concrete to set and dry out overnight (or a couple of days) before painting the top of the bollard.

To add to Daves post, we do the same thing except found an easier way. Chip down 6 inches hold the new post in and pour in hydraulic cement. It sets in 5 minutes and the post will not break out. We have set 30 inch stop sign this way and they have never failed. The hydraulic cement expands in the hole and gets real hot to the touch. Jim

Great suggestion on the hydraulic cement, Jim. Something that sets faster will be real helpful since I am usually "by myself". Does it speed up how soon you can paint and hope to have the paint stay? or Do you just paint the post and not worry about painting the concrete top? I have done that on some jobs and I think it looks pretty good that way. I am not sure of the real value of painting the concrete top anyway. But, I have had it show up on a punch list before.

I set them myself and hold the post until the concrete sets. About 5 minutes, if you are in a rush use warm water but you better be fast. Then it sets in under two minutes. You can paint the concrete in about 10 minutes.