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A floor grinding question

Jaguar Fan

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Mar 13, 2008
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Park City for Ski Season; Las Vegas for Poker Seas
Since floor prep is incredibly important, I decided to opt for grinding instead of acid etching for a do-it-yourself epoxy (or maybe a polyurea) coating.

Taking it one step further, I decided to call a few contractors (yellow pages) to get a quote to have them do just the grinding step. A few professional coating installers I called were not interested in doing just the grinding step. I turned to the yellow pages section for concrete contractos (sawing, demo, etc). Most were not interested in a small job (2 car garage) or only did commercial work (no residential).

Finally, I found one... I spoke with the supervisor and described the what I wanted (a surface prep to get the surface similar to 80 or 100 grit sandpaper); he called me back after talking to his guys and told me the following:

"when we do floor grinding, it is usually for someone who needs to get their slab level prior to installing tile, etc... maybe a tree root has caused the slab to heave or crack... and I talked to our guys, and the diamond blade (disk?) leaves the suface of the concrte extremely smooth, and that is the opposite of what you're looking for."

What should I ask for? Am I asking for the wrong thing?

In this case, the garage in question is not a working garage (the house is my mom's retirement house), and the slab is only 8 or 9 months old... but I view this as a learning experience for me in prepartion for doing a top notch job on my own larger garage later this year. For her garage, the most wear-and-tear would likely be hot tire pickup (it is in the desert in a suburb of Las Vegas).

Thanks in advance for any guidance
 
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Jabberwalk

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Jan 12, 2008
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Knoxville, TN
Call HTC at 877-482-8700. Ask for Clif Rawlings or Scott Williams. They manufacture floor grinders and get you a list of people in your area that can help you out. You can expect to pay between .50 and $1 per foot.
 

Charles (in GA)

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Jan 11, 2006
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50 mi south of Atlanta
If you have a smooth level floor, I would think you would want to steel shot blast it to get a clean, evenly rough surface. They make floor blasting machines just for doing this.

Charles
 

PAToyota

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Jan 20, 2006
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South Central Pennsylvania, USA
As others have said - shot blasting. Grinding is for when you have an uneven floor, not as much for preparation of a flat floor. If you had an uneven floor, I'd consider grinding it and then shot blasting it after that to prep it for paint.
 

Fuller

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Feb 10, 2008
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Location
St Pete FL
You can do a lot of damage in a hurry with a shot blaster if you're not careful. You also have the issue of "corn rows" - the area that gets hit twice as you slightly overlap your passes. On thin systems that can show through - it's not really a problem with a flake system or a high build system.

Can't say that I would ever grind and shot blast but you never know what might be the right call.
 
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byrd

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Mar 6, 2008
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175
get a floor polisher from a rental house. they have sanding disks in multiple grits that will sand the concrete. i work for a rental company and we used one of our machines to prep our shop floor before we coated it.
 

FL_Javelin

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Sep 14, 2006
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134
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SW Florida
I grinded and my epoxy is just fine so far (knock on wood). HD and Lowes rent them, I used the diamond blade. Yes it was fairly smooth afterwords but I have had no problems.

Maybe I am wrong for thinking this but isnt the main purpose of grinding/acid etching/blasting to remove the very top finished concrete layer? Something about that layers composition is not conducive to adhereing the epoxy to. I know I'm not saying it right, maybe others can clarify.

Again maybe I am wrong for thinking this but doesnt the epoxy chemical bond with the concrete more than finding a rough surface to grab onto?
 

sjsfire

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Feb 21, 2006
Messages
371
Location
illinois
Whe I did my floor last summer I went to the local tool renatal store and rented a EDCO grinder. $100 for the day but I had 850sq ft. so it took a while. I used the supplied carbide grinding blocks and got a good 80 grit finish on my floor.
 

sharpshooter

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Oct 24, 2006
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480
Location
West TN
I have a covered patio that someone had put fake stick on tile on top of to make it look like brick, Now most of them I can scrape off but others are harder and I cant scrape them up as easily, when I do get them up they leave some of the glue down on the concrete. I was going to use a grinder to try and get the stuff off but now Im confused as to what to do. Would acid do any better for me???
 

smartneasy

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Jan 30, 2008
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Location
Michigan
It is difficult to get a "professional" to come out for such a small job. You may be able to find a work alone epoxy guy to do it. Try advertising on Craigs list. You could also rent a grinder for about $150 for a day. They are simple to use. It would create a fair amount of dust that would be best sucked up as it comes off the grinder with a shop vac. The dust collecting connection is usually 2 inches. Your comments are correct in that you want to rough up the surface, not polish it. You need to open up the pores to allow the coating to stick. You also need to check the moisture content to be sure. Hope this helps!
 

smartneasy

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Jan 30, 2008
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Location
Michigan
There are good mastic removers (soy gel being one) that will get most of it off. Grinding may be needed for final prep.
 
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