Sanding Concrete Wall

Reply

  #1  
Old 10-06-17, 11:50 AM
Member
Thread Starter
Join Date: Mar 2009
Location: Northern Virginia
Posts: 3,892
Received 1 Vote on 1 Post
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.
 
Sponsored Links
  #2  
Old 10-06-17, 12:03 PM
XSleeper's Avatar
Group Moderator
Join Date: Dec 2004
Location: USA
Posts: 23,123
Received 194 Votes on 180 Posts
A paint brush and acetone.
 
  #3  
Old 10-06-17, 12:06 PM
Member
Thread Starter
Join Date: Mar 2009
Location: Northern Virginia
Posts: 3,892
Received 1 Vote on 1 Post
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.
 
  #4  
Old 10-06-17, 12:13 PM
XSleeper's Avatar
Group Moderator
Join Date: Dec 2004
Location: USA
Posts: 23,123
Received 194 Votes on 180 Posts
Is common to resurface concrete that needs to be "pretty". It's called topping mix.
 
  #5  
Old 10-06-17, 12:26 PM
Member
Thread Starter
Join Date: Mar 2009
Location: Northern Virginia
Posts: 3,892
Received 1 Vote on 1 Post
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.
 
  #6  
Old 10-07-17, 03:35 AM
Member
Join Date: Oct 2001
Location: USA
Posts: 924
Received 1 Vote on 1 Post
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
 
  #7  
Old 10-07-17, 07:26 AM
Member
Join Date: Oct 2001
Location: USA
Posts: 924
Received 1 Vote on 1 Post
BTW, any cementitious material applied directly to a substrate will crack if the substrate cracks.
 
  #8  
Old 10-08-17, 05:53 AM
Member
Thread Starter
Join Date: Mar 2009
Location: Northern Virginia
Posts: 3,892
Received 1 Vote on 1 Post
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.
 
  #9  
Old 10-10-17, 03:12 AM
Member
Thread Starter
Join Date: Mar 2009
Location: Northern Virginia
Posts: 3,892
Received 1 Vote on 1 Post
Just realized my original message says "brick ledge". I meant to say slab ledge. I'm referring to the inside of the wall, about 8" of which will be exposed.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
 
Ask a Question
Question Title:
Description: