Best Tool to "Sand" Concrete Down?

Angle grinder….cone diamond wheel…

-- A Planer? I'M the planer, this is what I use

Rent a concrete grinder. HD and lots of folks rent them.
https://www.homedepot.com/tool-truck-rental/Concrete-Grinder-10/50200-HD/index.html
Cheers!

-- If it wasn't for bad luck, I wouldn't have no luck at all, - Albert King - Born Under a Bad Sign released 1967

like Bandit said one of these on a grinder. They make fast work out of grinding down concrete. https://www.amazon.com/s?k=Diamond+cup+wheel&i=tools&ref=nb_sb_noss.

What do you mean by “Fair amount”. You mentioned just around some posts. That will determine if i would recommend angle grinder or renting the big machine. Btw, make sure to keep it wet to keep the dust down or it will make more dust than you can believe.

Your title says you want to sand down concrete, but the description says it’s the caulk you want to get removed. What kind of caulk and again how much will matter here. I’d think you’d want to scrape off the caulk first or it will gum up any grinding wheel you use. Though maybe not if you’re willing to dig enough into the concrete.

If you’re just removing caulk, I don’t see why you would need diamonds. HF has a grinding disk imbedded with carbide chunks. $10.

You might also try heating the caulk with a torch or heat gun and scraping it off.

-- I admit to being an adrenaline junky; fortunately, I'm very easily frightened

Heavy duty sanding disks for your 4 1/2” grinder will do the trick. You need a rubber pad. The HF stuff would work fine, and buy a grinder and the pad while you are there or at HD. It’s mandatory equipment for any DIY’er. With a different disk, you can grind the concrete, or cut metal, etc….

Also a torch and scraper should work fine too.

Like others said, if it’s not much concrete, a cheap masonry wheel in an angle grinder will work. Be aware that concrete dust contains silica, which is really, really bad for the lungs (http://www.dcpolish.com/concretegrindingdanger.html) Wear a mask.

-- Jeremy, in the Acadian forests

I would use a rub block to get the bulk off so you aren’t loading up a wheel. Something like this.
https://www.homedepot.com/p/ANVIL-6-in-x-3-in-20-Grit-Rub-Brick-57457/300976865

Once the big stuff is off you can clean up with a grinder and work pretty fast.

My 4,000 psi / 3.5 gpm pressure washer would remove this using the rotating turbo nozzle w/ little effort.

If you re just removing caulk, I don t see why you would need diamonds. HF has a grinding disk imbedded with carbide chunks. $10.

You might also try heating the caulk with a torch or heat gun and scraping it off.

- runswithscissors

Be careful not to heat the concrete too much with the torch. Chunks could explode if there is embedded moisture.

I suggest a guy named runwithscissors should try it first. :)

-- Steve

If you decide to go with an angle grinder/cup type grinding wheel and you’re indoors you should consider one of these shrouds. They’re a pain with the vac hose and visibility in infringed so it’s a bit more difficult to keep it flat and not gouge the concrete but the dust is KILLER!

They also have a 7 inch version which I think would be a bit easier to keep flat on the floor.

https://www.homedepot.com/p/Dustless-Technologies-5-in-Universal-Dust-Shroud-Pro-for-Angle-Grinders-D1805/206024974

look at www.diambrush.com

I have used the this (https://diamabrush.com/product/hand-tools/) to remove thinset, mastic and paint from concrete and it worked pretty well. You will want to have some dust collection on the angle grinder and wear a respirator too.

I tried concrete polishing and grinding discs but they did not work well to just get off what was on the concrete, they either did very little or dug in to much.

these do work best on smooth hard concrete, if the concrete is rough or soft, it will dig in if you are not careful. Also a variable speed angle grinder seemed to work best at slower speeds and the blades lasted longer too.

https://www.harborfreight.com/air-needle-scaler-1108.html

If it is just the caulk you want removed and no actual concrete, I would scrape most of it of first then try a stiff wire wheel followed by some coarse sandpaper to get what’s left. There are also some caulk removers that dissolve the caulk that could be worth a try making it easier to scrape off (I’ve never tried them myself). I would not resort to the diamond or other masonry wheels with an angle grinder unless that doesn’t work.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.