Sand concrete?

[Steven in Iowa]

I have a 2 1/2 stall heated garage that doubles as my workshop and need to clean up the floor.  It was a business at one time and had tile glued down, but have since been removed, leaving some old paint and mastic.

It isn't real bad and I figured I could skim over it real lightly with my RO 150, but I'm not sure what to use for sanding media.  I don't need to remove any concrete, just the residue.

 

[Brice Burrell]

I'd try 24 or 36 grit Saphir.

 

[Iggy1965]

There is a special sander for concrete, and the nice thing is Festool makes them. Look at www.protool.de under 'sanieren'. It is in German.

 

[Bill in seattle]

steve
you have a sticky problem at best, but here are some tricks that might work, I assume theres no asbestos issue as that is a issue in itself.
first I would try some saphire 24 on the rotex. only let 30/40% of the disc get in the paint/ mastic at a time to let the vac suc and keep heat down.
second, get a bag of sand and throw down a good heapin pile of it on the area to clean up. vary the speed of the rotex and grind the sand into the paint/mastic,using a 24 saphire. the sand will help absorb the goo and not stick to the saphire as much. you will need to watch the disc and change it when it gets all gummed up. if it just gums really fast try a vlies 100. try without vacuum on at first or at the lowest setting if dust is a big issue. the key is to keep heat buildup down and let the sand grind away and absorb the goo. it will break down fast. keep repeating this if it appears to make decent headway. this is NOT a speed job so be prepared to spend some time. this method has been successful many times.
Another way to try is find a stone supplier distributer or someplace that sells diamond grinding pads/wheels. get a diamond cup wheel coarse or a s/c abrasive wheel. put them on a angle grinder and grind away. this will be dusty/ messy at best, have someone hold a vac near the pad while grinding to help if you can't find a dust shroud for the grinder.
good luck, this is one of those crappy jobs with no easy answer.

 

[Bob Marino]

Brice aqnd Bill have given some really good advice, especially Bill's recommendation of using sand to absorb the mastic.
I sanded my old painted cement floor recently (no mastic) as well as smoothed down new bare cement, with Saphir 24/36/50 grit. You'd be amazed at how well that paper holds up.

Bob

 

[Loren Hedahl]

Another tip:  Since you're in Iowa and it is winter time, you have at least one good thing going for you!

Turn off the heat!  Open all doors and windows!  Wait until morning and go for it!

I recently did a couple of rooms with glued down tile.  The one done last summer seemed to be twice as hard to remove the mastic as the one a couple of weeks ago.  What I ended up using in both cases was a wide wood chisel, bevel side down, sharpened at about 30 degrees or less.

I found the sanding discs gummed up almost immediately, however I didn't think of strewing sand around.  That might have made all the difference.  At this point, I'm pretty sure I don't really want to find out.

Good luck.