View Full Version : Best way to remove concrete?

02-09-2003, 09:08 AM
Ok, now that Ive got the I-beam situation under control, I have another question.
The Acorn welding table i bought was located in the floor of a shop. It is 5' x 5' and 5" thick. There is concrete stuck all over the underside and to the sides. I was going to use an air chisel to knock it off, but though someone may have a better idea...ie hit it with Canadian meatloaf 3 times and it will run away.

02-09-2003, 11:15 AM
Your idea on using a chipping hammer is a good one especially if it has any thickness. If it is thin you can use a masonry grinding disc available at Home Depot or Lowes and grind the concrete away. I makes a lot of dust so wear a respirator. I have used them to grind concrete slabs that have minor raised section prior to putting down new flooring. Muriatic (spelled wrong)acid will also eat the concrete but it is messy to use.

Whatever you use wear safety equipment so you get to use the new shop.

Hope this helps.


02-09-2003, 11:22 AM
Does that mean Muriatic acid spelled right won't work?

02-09-2003, 11:31 AM
We picked up 6 of these welding tables for $500. One is not too bad as far as the concrete goes, the other 5 have 3-4 inches on the underside. THese tables are cast iron with 1 1/2" square holes all over. The underside is webbed (about 1" high webs) which i am sure will make the concrete bond really well.
Since these were in the floor, they are in really nice condition, none of the 6 have so much as a chip or notch from an errant grinder.

02-09-2003, 01:04 PM
Think I would wet it to the point of soaking and go after it with the chipping hammer. This will hold down the dust.

The muriatic acid attack the lime in the concrete and will weaken it. It won't completely remove it. It is uused to clean the bricks on houses to remove the mortor. The 1" web will complicate the removal of the concrete.

02-09-2003, 01:26 PM
How about using a torch? I know that when I was welding with an acetylene torch close to concrete, the concrete expanded and popped. You can take a torch and make it flake off the iron, but watch for flying concrete and use eye protection because it really flies! Muriatic acid should get the residue.

02-09-2003, 10:14 PM
See if you can drill some holes in the concrete and insert some close fitting wooden dowels and then wet them. When the wood expands it should pop off big hunks of concrete.Remember the older the concrete the harder it is and the tougher it is to remove.

NEVER use muriac acid in the same room you have precision tools. Just the fumes will rust any exposed steel surfaces.

02-09-2003, 11:58 PM

In the abscence of my sister's meatloaf, try a small electric rotary hammer and a carbide chisel - be careful of the cast iron though! Guys that work with granite drill holes, score a line and pound wedges in - this splits the granite in half.

02-10-2003, 06:31 PM

Does your sister have any other favorite dishes. Is she a specialist in meatloaf or does her cuisine offer other treats. Is there a cookbook available?


02-10-2003, 09:15 PM
I seem to recall the literature for Kano Kroil stating that it was helpful in removing dried concrete from tools. Worth a try.

02-11-2003, 12:08 AM
No, she can also burn water... http://bbs.homeshopmachinist.net//biggrin.gif
Safest way to eat in her house is "take out".

02-11-2003, 02:59 AM
I am wondering if the concrete is there for a reason or not. Having that extra mass may be an advantage. If it is on the underside and not affecting its use I think I'd leave it alone. That mass may help keep the surface from overheating and warping. That is just my two cents (and over priced at that!) Of course if it saves you some needless labor maybe it is under priced. A day or two of chipping concrete it probably worth at least a case of beer.

02-11-2003, 10:10 AM
thanks for all the replies.

The tables were built into a floor, apparently dropped in while the concrete was wet leaving the undersides full of concrete. I think this is the 'good' 4000lb concrete based on the shop is was in (ship building shop.)
I am thinking of using an air chisel to remove what i can and then drilling holes in whatever is left and pouring the muriatic acid in. These things are really full of concrete...the guy that delivered them figures they weigh between 3000-4000 lbs each (the tables are listed as only weighing about 2000lbs)
I would like to get most of the concrete off, because it is blocking the square holes in the top. I shoudl really post a pic.

OH, Spence, I will buy you a keg of beer for each plate you clean if you are so inclined...thats 6 kegs!

02-11-2003, 11:48 AM
How about getting the plates mounted on whatever stand you will be useing, and then just drilling with a roto-hammer through all the holes?

You can use a bit that just fits freely in the holes, and it will remove most of it and then finish with the air hammer.
The extra weight of the concrete will deinitely come in handy someday http://bbs.homeshopmachinist.net//biggrin.gif

02-11-2003, 12:20 PM
I think this job is too big and that you should throw the plates away. The best way to do that is to put them on a truck and pay to have them delivered to me in Mississippi. Once they arrive I will make sure that they are disposed of properly. You can keep one for a keepsake.

Good luck.

02-11-2003, 10:10 PM
Hey Murf23,

I wasn't offering two days of labor for a case of beer. The case of beer is just for coming up with a good reason not to do all that work. And after a few beers all that heat absorbing concrete will start to look good! I once was asked to make a hole through four feet of concrete with an electric jackhammer. Thing was, the hole was to go through a buildings foundation horizontally for some high-voltage power conduits. I got lots of compliments on how I solved the problem of working a jackhammer side-a-way's with harnesses and slings but that was the end of my concrete busting days. After that I started learning how not to be the one using the jackhammer, or mucking out the hole. I don't mind supervisin' though. Hey, is that beer cold yet!?

02-11-2003, 10:20 PM
You pay for the plane ticket, the chisels, the beer, the lunch, the tent, the outhouse & shower, and you got a deal.

Have meatloaf - will travel. http://bbs.homeshopmachinist.net//biggrin.gif

I'm bored anyway.

02-11-2003, 10:33 PM
One more idea for you (no charge, not even a beer.) Ok, this the idea. Assuming you have access to a hoist and have put the tables on pallets. Have the tables put upside down and on thick plastic sheeting. Tape up the sheeting and fill with as much water as it will hold. Off-load on the North side of the building. Wait for the coldest night of the winter when they are really hard frozen. Then drag them into your shop with your truck, and hose them down with hot water. What do you think? Any chance it would work? Sure beats swinging a sledge hammer.
On the other hand, the sooner you start, the sooner you finish.

charlie coghill
02-11-2003, 11:53 PM
There is a material that is used to bust rocks without using an explosive. You drill a hole in the rock and pour this stuff in and as it cures it expands and evently will brake the rock. Sorry, I don't know the name of the stuff or where to find it. I would guess in a stone supply store or maybe a lumber yard. The company that I worked for would use it to break rocks that rolled into the cannels. Hope this will give you another idea.

02-12-2003, 10:55 AM
SJorgensen: I suspect the cold hot won't work because iron concrete have about the same rate of thermal expansion.

I was told (right or wrong) that iron for rebar sticks only because the rates of expansion are so close.

But then we used bamboo/concrete and it worked well too.

02-12-2003, 10:59 AM
Last night I was reading "Busted Tractors and Rusty Knuckles" a standard textbook on rebuilding old tractors. Roger mentions pulling a metal post out of the ground that had concrete on it. An old timer goes by and suggesed that he tap on the metal and let the vibrations break up the concrete. You might be able to do that with the welding table, what do you have to loose?


02-13-2003, 12:11 AM
Don't whack the cast iron! You could crack it instead. You could always use acid.