I polished concrete which turned out to be poor quality. What next?
April 28, 2017 7:31 PM   Subscribe

I had a concrete slab polished which included a section which (when poured) was an outdoor breezeway, but is now inside the house. Much of the slab turned out great, but the outdoor breezeway area was of poorer quality and ended up polished, but pitted and not smooth. What is my next step, if I'd like a smooth, hard finish? Appearance doesn't matter (I'm going for modern/industrial)
posted by arnicae to Home & Garden (7 answers total)
 
There are resurfacing patch materials that could be applied, then a layer of paint. Was any material applied with the polish? That may alter how another layer sticks.
posted by nickggully at 7:36 PM on April 28, 2017


Do you want it to look like raw concrete? If not an epoxy paint/coating would be the industrial way to address this.
posted by Mitheral at 7:52 PM on April 28, 2017


An clear epoxy fill would give you the smooth hard finish, and probably wouldn't look half bad, either.
posted by bricoleur at 7:55 PM on April 28, 2017


Water glass is the traditional concrete sealant:
Concrete treated with a sodium silicate solution helps to significantly reduce porosity in most masonry products such as concrete, stucco, and plasters. A chemical reaction occurs with the excess Ca(OH)2 (portlandite) present in the concrete that permanently binds the silicates with the surface, making them far more durable and water repellent. This treatment generally is applied only after the initial cure has taken place (7 days or so depending on conditions). These coatings are known as silicate mineral paint.
It's cheap, widely available, easy to apply, has no or very low VOCs, and drys rapidly; it's also very hard and durable, and it's shiny.
posted by jamjam at 9:10 PM on April 28, 2017 [3 favorites]


Colored epoxy makes a good effect, a bit like marbleizing.
posted by parmanparman at 2:58 AM on April 29, 2017


Epoxy would be good. Polyurea would be better. I've got polyurea floors in both my garage and basement. It's good in the garage (though not as tough as I'd hoped - I've put a few gouges I to it in five years of use) and excellent in the basement (no motorcycle kick-stands to scar it) where it turned a mixed quality aging concrete floor into a pleasant place to be.
posted by DaveP at 2:58 AM on April 29, 2017


It's pretty simple to patch/refloat the floor, if what you're shooting for is a smoother surface. You apply it similarly as you would a wall patch; i.e., if it's a small area, apply with small spackle spatula, sand, reapply, sand, fine sand, then polish or paint. Larger holes may require either new concrete pour, or some sort of mesh/rebar to give it strength. If it's a wide area, with lots of tiny pits, you can use a big grout float tool, and just push the patch material over the whole area, sand, refloat, fine sand, polish/paint.

I've had good luck with a couple of different methods for concrete floors, and fixing little pits looks intimidating, but is pretty easy. Quikrete is my personal product of choice, (not affiliated with them), and they have some pretty good videos, like this one, on how to do concrete repairs.
posted by SecretAgentSockpuppet at 10:02 PM on April 29, 2017


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