Can You Polish Old Concrete?
The passing of time doesn’t have to mean passing up a great-looking floor. Learn how to polish old concrete with professional help.
Key Takeaways:
- Old floors can be polished
- They’ll likely require surface preparation techniques like grinding or shot blasting
- Repairs might also be necessary
- Densifiers can be used to harden the concrete and make it more durable
The Great Wooden Pyramids of Luxor. The Steel Coliseum. These don’t exist because it seems people have always known that if you want a material that ages well, you choose concrete. It won’t rot like wood or rust like steel and can shrug off the decades with ease – if environmental conditions are favorable and stable, that is.
It’s when there’s too much of one thing (or the same things too often) that the cracks literally start showing. This is when many property owners start wondering, “Can you polish old concrete?” The good news is that most senior surfaces can be buffed to a spectacular shine – it just takes some prior assessment and prep work to make it happen.
The old gray floor it ain’t what it used to be
Several factors can influence the health and lifespan of concrete. A three-year-old floor could look like it’s thirty, and vice versa. It can be damaged by electrochemical reactions, suffer oxidation/corrosion from underlying rebar, or simply not last very long due to a subpar blend, too much/too little water, or shoddy work by the contractor.
Some signs of deterioration include:
- Cracks: This can result from old concrete shrinking, possibly caused or worsened by the carbonation process, which can lead to fragile concrete. The surface may also have been overexposed to physical force.
- Spalling: Results in pitted or flaking concrete and chips of varying sizes. Scaling has a similar effect to spalling, only on the finished surface.
- Water damage: Spalling could result from water damage, as can paint peeling.
- Discoloration: May be caused by mold, alkali, or water vapor, depending on the color of the stain.
If any of these are present, polishing your concrete surface will be a more complicated procedure but not an impossible one. Here are some methods a contractor might suggest to polish old concrete.
How densification aids polishing
It’s important for customers to know that not all old concrete can be polished. Surfaces that are hard enough and structurally sound (and which take densifiers well, where necessary) are the ones that can be polished successfully. Densifiers are a liquid chemical coating that won’t fill in any imperfections but will strengthen and support the structure of the concrete and bond the sand more effectively with the cement’s matrix.
This has the added benefit of making the concrete’s surface more resistant to liquids and abrasions. Surfaces that are tougher against abrasions retain their shine more effectively. Therefore, densification is a common pre-polishing measure. Densifiers also allow the concrete to be polished more effectively because the aggregate and sand won’t get pulled out of the surface during the process.
Polishing old concrete is essentially like sanding knotted wood. You can’t sand the knots away. You can smooth the surface, but you’ll still see the knots. It’s important to understand that old concrete has a history that gives it visual character and patina, and that this history will still be visible after the floor is polished.
Contractors can patch, grind, and fill any defects that exist in the slab, but whatever’s there is still going to be there after polishing. Just don’t be discouraged!
Old concrete can still look great
At Concreate, we’ve successfully polished concrete that was 80 years old. Older surfaces can also be ground deeper beyond the defects to create an exposed look like a terrazzo finish. Sometimes, it’s even the case that older concrete turns out the most visually attractive as it can have really unique aggregates.
Even if your site’s surface can’t handle necessary repairs and you can’t live with any imperfections remaining visible, a contractor can do a surface preparation and put down an overlay that will create a new surface. Just be aware that it’s this new surface that will be polished, and not the old concrete underneath.
Grinding is one method of surface preparation that might be used. It’s a slow but steady method using diamond-coated pads to grind the old surface to the desired grit level. The density of diamonds in the pad increases with the grit level, and the more grit you use, the higher the shine you’ll get. Grits can thus be tailored to a customer’s wishes, which may be a matte finish, a semi-gloss, or a very glossy surface.
The polishing process isn’t right for every floor
Sometimes, skipping polish altogether may be the right choice for your site if the floor requires extensive patching, is too uneven, or is simply in a building where day-to-day activities will harm the polish. Read our earlier blog on polished floors, even if you’re sure your old concrete is up to the buffeting.
Yes, it’s cost-effective, durable, and low maintenance, but it’s also a bad choice in areas where people will be standing for a long time or where chemicals or water might get on the floor. Additionally, some old concrete floors have stains that just won’t come out, meaning they’ll still be visible even after polishing. You may find this to be aesthetically pleasing and if so, polish away!
We hope this article has helped you toward the right decision for your old concrete floor. We also made the entire polishing process transparent in our previous blog, where you’ll find a step-by-step walkthrough explaining how we consider each job’s unique requirements.
Connect with us with any concrete questions
Can you polish old concrete? Yes, you can! You just need the right professionals at your side. At This is Concrete, we bring a high level of experience to polishing jobs and many other concrete-based services.
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