Sanding concrete repair?????????????????

[TahoeTwoBears]

Don't laugh quite yet. I used Concrete Fixall to patch the edge of my garage floor where it protrudes beyond the door. It's subject to freeze/thaw cycles and takes a beating. My first application has cracks so I plan on adding a skim coat in a few days to finish it up. My question is this - has anyone ever tried to sand something like this? My skim coat will feather back into the finished floor. I thought that with the proper abrasive, I might be able to make it look halfway decent when I finished. What do you think?

Mike (the non concrete guy)

 

[Brice Burrell]

There was a thread were Bob Marino (and/or someone else???)mentioned sanding his/their basement floor(s) to remove paint and/or concrete. So I guess it can be done. You may have other problems, thin concrete patches when subjected to freeze/thaw cycles tend to fail quickly. Other products made specifically for this hold up better than concrete.

 

[Tinker]

I would not use a sander for planing down concrete. You can ruin the sander and not do much damage to the concrete. You can rent tools for the purpose.
I have been out of the business for over 25 years, so there may be new tools and, certainly, new products on the market since i "retired" from the trade.  I have ground down several floors using a rented Terrazzo machine.  They are heavy enoogh to make the impression needed to grind down the concrete. (ask a tile contractor about a source)

From what you are describing, I don't think your efforts will provide the results you are looking for.  If the concrete is cracking, you are haveing problems from frost heaving.  no amount of refinishing will stop that action.

If it is spalting (scaling) that is the problem, you may be correct in your accessment of freeze thaw cycling.  However, had the mix and slump been correct, and the finishing at time of pour been properly done, you would not now have the problem. I suspect that salt may also be the culpret.  you may not be putting any salt on your own driveway, but you are tracking enough in from the highway to give you problems.  No amount of refinishing is going to give protection against future spalting.  The salt has worked in too deep already.  Poor mix with too much water can not be fixed with an overlay either.

Without further knowledge of what is actually happening, I would guess the solution to be what you are trying to avoid>>> The expense of tearing the apron out and redoing.  Get a reputable mason who understands the correct mix and correct amount of water (slump) and will do the work according to code.  Otherwise, you have an ongoing problem that will either give you fits, or you will learn to ignore.

Sorry for the prediction, but I've been there seen that done that enough times to have an idea of what I am taking about.
Tinker

 

[TahoeTwoBears]

Thanks, everyone. I read the posts re: the concrete countertop thread and have decided that there's no way I want anything Festool involved involved in this project. I'm guessing that next year I'll have a pro do a good removal and fix it properly. Too many projects happening this year to try to fit it in prior to cold weather/snow (October).

Tinker, I suspect you're right about the mix. It's 33 years old, but has been a problem off and on over the years. Fixall lasts for a few years, but doesn't look right from my amateur efforts. Time for a pro.

Mike

 

[Trevor H]

I too have sanded concrete patches many a time, but not with a Festool. I use my Clarke Edger with a 16-4 grit paper and make darn sure you don't wear through the paper or you are buying a new pad. A RAS? , maybe, but i don't know if i would put my beautiful festool through that much pain. Heres some pictures of what not to do with a RAS. Now keep in mind this RAS is only two months old.

The guy that bought this RAS obviously used it for the wrong application, not to mention his employee forgot to lock the lever which therefore locks the shroud.

If i were you i would knock down the concrete with an edger for sure. You can usually rent one pretty cheap then you don't have to worry about the pad.