Cleaning old mortar from floor before sealing

[afazz]

I ordered some Ghostshield 4500 + 8510 to seal the floor in my garage (380 sq foot tandem). I moved everything out to scrub away what I thought was just dirt and crud, but it appears to be a thin film of dried mortar. I assume it's from block work done on the walls when the garage was built ~20 years ago. I was able to successfully clean small portions with a wire brush, but obviously that would take forever. I tried muriatic acid diluted 12:1 and it didn't remove anything.

I can rent a floor sander or grinder, would something like this "coating removal tool" from Home Depot rental leave too coarse of a finish for sealing? Should I be looking to rent polishing equipment? Stronger acid mixture? Any other tips or suggestions?
https://www.homedepot.com/tool-truck-rental/Coating-Removal-Disc-7/12569/index.html

I'm not looking to make a showroom, I just want some basic protection from oils and easy cleanup of dust and water.

 

[dcg9381]

I've got a newer slab and looking at the same thing. Some old powder / motor from "other" concrete - maybe 1/16" high, but you can tell it's there.
We've been messing with it this weekend. The hand-held scraper from Lowes will get it off, but it's a lot of work. We may try a moderate grit floor polisher. I'm going to try to do it "wet" and see how that goes.. But like you, haven't done this before and concerned that if I start grinding/polishing, I'll have to do everything...

The disc tool you've referenced is for removing substantial amounts of concrete - I think it's too course, but welcome to get another opinion.

I have used these polishers dry (not the course diamond version you're noting) and they do not leave it too course for sealing. I've used polyurea. The first coat will take a decent bit of polyurea because it is porous.

 

[afazz]

That’s an interesting thought about the scraper, I didn’t think of that!

I ended up renting the coating removal disc and tried it out. It’s a little more coarse than I would prefer, but not bad. I sprayed the densifier Saturday night, sealer next weekend. It’s a penetrating sealer so I don’t think it will get any smoother, but that’s ok. I’ll report back when it’s done.