Sanding Concrete Wall
#1
10-06-17, 11:50 AM
Sanding Concrete Wall
The concrete contractors used styrofoam to form the brick ledge on my newly poured foundation wall, which, as you can imagine, left styrofoam remnants embedded in the concrete and associated pitting. This will be visible from inside the garage as it is above slab level. What is the best way to remove this? My best guess is wet sanding the wall with a diamond sanding pad and orbital sander.
#3
10-06-17, 12:06 PM
Didn't think of that. However, that won't remove the pitting. Acetone to remove/dissolve the styrofoam followed by a light wet sanding perhaps? Would #100 grit be sufficient? I'm not looking for perfection, but I don't want the wall to look like it sustained buckshot. I can get 50, 100, 800, and 1500 pads from my local big box for under $10 each. They are 4" diameter, so use with my angle grinder I suppose.
#5
10-06-17, 12:26 PM
Okay. I suppose that would be acceptable. It is an unconditioned garage, so my concern is with the coating chipping/flaking off over time or if/when it is bumped. This topping mix can be used on vertical surfaces? The only other concern I have with this is the topping will need to "wrap" around the top of the ledge as well, up against the sill plate. If it needs to be thick, then it will be obvious. Too thin and I'm concerned it will crack.
Quikwall surface bonding cement sounds more appropriate. Still have some of the same concerns though. I think I'd prefer they sand the pitting away. It's only a 6" tall 30' long ledge and not the entire length.
Quikwall surface bonding cement sounds more appropriate. Still have some of the same concerns though. I think I'd prefer they sand the pitting away. It's only a 6" tall 30' long ledge and not the entire length.
#6
10-07-17, 03:35 AM
Once you mostly get the bits of styrofoam removed, you can coat the wall with Thoroseal. It's a top quality coating/waterproofer that's been in use for many, many years. The PDS sheet says two coats, but you might be able to get by with one if you're not concerned about actual waterproofing. You may have to call around to contractor supply houses, not sure if it's carried by the big box stores. http://thoroproducts.com/pdf_info/th..._sellSheet.pdf
#8
10-08-17, 05:53 AM
Acetone worked like a charm 
My plan is to now smooth down the wall with a 4-1/2" dual row diamond cup wheel using my angle grinder. I'll admit this makes me a little nervous since my grinder is not variable speed. It's fully on or fully off. I'll be sure to practice on an area that won't be visible first. I'm not looking for a perfectly smooth finish. I simply want to knock down the craters remaining from the Styrofoam. I took a sanding stone to one area to see the effect, and it did the trick.
My plan is to now smooth down the wall with a 4-1/2" dual row diamond cup wheel using my angle grinder. I'll admit this makes me a little nervous since my grinder is not variable speed. It's fully on or fully off. I'll be sure to practice on an area that won't be visible first. I'm not looking for a perfectly smooth finish. I simply want to knock down the craters remaining from the Styrofoam. I took a sanding stone to one area to see the effect, and it did the trick.
