Want to reuse an old marble slab? First, you have to clean it up. Here’s how to get concrete off of marble countertops!
Our local university did some renovations, and in the process replaced some lovely marble countertops with… I don’t even know what you’d replace marble countertops with. What’s the upgrade from marble?
Anyway, these former lovely marble countertops, now lovely slabs of marble with ugly pools of concrete underneath, went at dirt-cheap prices to the university’s surplus store, where we snapped them up, because marble.
I wanted to use them just as shelves, because who doesn’t want random rescued marble shelves around their house, but the giant pools of concrete on the bottoms, several per slab, were a huge problem. They’d interfere with the shelf support brackets. And they’d be visible, and visibly ugly.
You can sand and grind concrete off of marble, but how long would that take? Probably forever. Definitely not worth it for random shelves.
Fortunately, one of my kids has the occasional hobby of hand-carving limestone (limestone is kind of a thing here in Indiana), so we’ve got a basic set of chisels, and that, combined with the visual of my kid using them to chip away at rock, gave me the idea to try the same thing with concrete.
It worked like a dream!
How to get concrete off of marble countertops? Chisel it!
To remove the concrete from the marble, all I had to do was press a sharp chisel into the place where the concrete met the marble, then give it a few gentle knocks with a hammer. A chunk of concrete would break away, leaving some concrete residue, but overall looking surprisingly clean.
Mind you, this was TEDIOUS work. I couldn’t even indulge in my usual fallback of watching Gilmore Girls on Netflix while I worked, because the hammer was too noisy. If you don’t have children who at any moment could be catching something on fire or deliberately blocking each others’ airways if you don’t constantly listen for suspicious silences and move to intervene, you could wear a nice pair of headphones and zone out on a podcast, but I mostly just tapped away and suffered.
After I’d chipped away all of the concrete, I was left with spots of concrete residue where each of the pools had been. The palm sander easily sanded these away, and if I’d been dedicated to the proposition of completely cleaning the marble slab, I could have switched to finer grits and eventually had the slab polished and looking quite lovely and new. I do, however, actually like to see the evidence of an object’s history in its wear–pools of concrete notwithstanding–so I did not take care to sand away all the little stains that I could have.
Although I love the way that the marble turned out, after such a surprisingly easy fix, I’m less sure of the marble shelf itself, the one that you can see in the top image. This one is really just a test shelf, to double-check that the method that we used to secure it to the wall will actually hold it and its stuff–after all, that marble slab weighs something like 40 pounds! After a few months without that particular shelf falling and taking out half the wall with it, I’ll begin to seriously think about what I actually want my marble shelves to look like. I really like the look of these leather strap and pine board shelves, especially because I could probably upcycle a couple of leather belts to make them, but I’m also open to suggestions, so if you have any great ideas, let me know in the Comments below!