Cutting concrete posts

Old 02-13-10, 10:42 AM
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Cutting concrete posts

I've got four 4x6 inch concrete posts with rebar that I need to cut through. I need a clean cut and cannot demo them. My cheap cordless Black and Decker saw with a masonry blade didn't stand a chance. Should I rent a cutoff saw and buy masonry abbrasive blades for it? Can the abrasive blades cut 1/2 inch rebar, or would I need to switch to metal cutting blades for that? Should I expect to destroy one blade per post? Or maybe instead of renting I should buy a better saw, or 7 or 9 inch angle grinder? Thanks for the help.
Old 02-13-10, 11:44 AM
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I'd consider renting a gas auger and drilling the post holes deeper. A corded 7" circular saw with a cheap ($25-$30) diamond dry blade should do it but go slow. You will have to go from each side.

The problem with carbide masonry blades is they get smaller as you cut and you need to cut to full original size of the blade on both sides. Replace enough of those and you have spent more then the cost of a diamond blade.

It is iffy even with a 7" blade to cut all the way through so I would want Sawzall with a carbide blade to finish the cut.

There are other less DIY practical but easier ways such as an oxy-magnesium cutting torch.

You may also be able to find a company that specializes in cutting concrete willing to cut them off.
Old 02-13-10, 12:52 PM
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Another thought is if you wanted to go the cheap route and use a 7 1/4" circular saw is to buy both masonry and metal cutting blades.
The rebar will grind down the masonry blade pretty quick.

I would say the simplest and best job will be with a gas powered concrete saw.
They make a demolition disk that will cut concrete with rebar and do it pretty quickly.

You would rent the saw and buy the disks for it.
Old 02-13-10, 02:04 PM
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More info? Why not just pull them out? Or knock off all the concrete after making some cuts in the concrete..then using an angle grinder to cut off the rebar?
Old 02-13-10, 03:07 PM
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I was going to suggest shaped charges, but nevermind. Drilling holes in it will weaken the concrete so it can be beat off and the rebars cut as Vic suggested.

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