Concrete is durable, quite versatile, and cost-effective – being used to form driveways, sidewalks, interior flooring, countertops, and numerous other products, and it’s more popular than ever before. Join me as we learn about the ways that concrete can add value and beauty to your home, and how you can save thousands of dollars by doing your own concrete work relative to hiring a professional.
Are you ready to learn some “hard” lessons about concrete?
OK – let’s get rockin’!
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Can You Sand Concrete?
Before we go any further, the answer is a big fat YES – you CAN sand concrete. However, the process isn’t the same as sanding a piece of wood, plastic, or metal. Concrete is its own animal, and it requires specialized tools, and a bit of insider knowledge, to achieve the best results when sanding.
Why Sand Concrete?
There are loads of reasons for sanding concrete, like removing imperfections on the surface, removing stains or coatings, repairing cracks and pits, and polishing to achieve a glasslike finish. Let’s look closer.
Made by mixing water, cement, and an aggregate (typically gravel), concrete is super-durable. Sometimes, after curing, concrete has imperfections like sharp edges or aggregate protruding from the surface that could trip someone or damage tires. You can remedy these issues with sanding to enhance appearance and improve safety.
Stain or Paint Removal
Sometimes, old paint, oil stains, and other surface contaminants penetrate into concrete too deeply for detergents and solvents to remove. In many of these cases, sanding can take stains out that other methods can’t touch. Plus, sanding concrete involves no toxic chemicals, which is always a good thing.
You might need to sand your concrete after repairing cracks or pits with any of the various types of fillers. The medium will need sanded flush with the surface to maintain smoothness and enhance its appearance.
Most people who sand concrete do so to enhance the finished texture and appearance. If you’re planning to apply paint or stain, then sanding accommodates better surface adhesion.
And if you’re not painting or staining, then sanding and polishing are needed to achieve the most attractive look. Whether you want a glasslike polished finish or an exposed-aggregate appearance, sanding’s a must.
PRO TIP 1: Concrete can be dry sanded or wet sanded. Dry sanding tends to be more common, but I definitely prefer wet sanding and polishing. It makes a mess and requires clean-up, but I’m a clean freak anyway.
Also, cleaning up the wet mess, to me, is much better than dealing with microscopic dust particles that go EVERYWHERE, including inside my respiratory tract! IMO, wet sanding concrete (and drywall) yields superior, more fluent results.
Step-by-Step Guide to Sanding Concrete
OK – let’s get into the steps to take when sanding concrete. Of course, there will be differences in your approach depending on if you’re sanding a small countertop, the floor in your garage, or your entire driveway. However, the basic steps remain the same.
Ready to sand some creet? Let’s go!
STEP 1: Choosing the Proper Tools for the Job
There are various types of concrete sanding tools, and the type you’ll need, again, depends on the nature of your project. Sanding and polishing countertops or concrete furniture typically only requires a handheld concrete polisher, which is sort of like a right-angle grinder.
Comparatively, if your project is larger, like exposing the aggregate in your garage floor, you are probably best suited for renting a stand-up walk-behind concrete finisher with a large rotating sanding disc beneath.
And if you have a huge project, like refinishing a ¼-mile-long driveway, for instance, you should consider pricing a commercial concrete grinding machine, plus a skilled operator.
PRO TIP 2: Note that sandpaper used on wood, plastic, and metal will not work well for sanding concrete. Once you determine the best tool for the job, you’ll need to determine the best grit of diamond concrete sanding or polishing pad to use.
The best grits for your project will depend on your specific goals. And like when sanding wood, you’ll need to start with a coarse grit and work your way up to the grit that delivers the intended finish.
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STEP 2: Get Your Gear Ready and in Place
Clear your work area of any unnecessary items, stretch extension cords where needed, lay your tools out where they are easily accessible, and get your safety gear (goggles or safety glasses, respiratory protection, gloves, ear plugs, sturdy shoes, old clothes) prepared for when you’re ready to begin sanding. A little extra time spent prepping will yield easier work, fewer headaches, and a better finished product.
STEP 3: Protect the Work Area
Dry sanding concrete is an incredibly dusty process. If you have indoor concrete sanding to do, you’ll need to:
- Place drop cloths on the floor
- Meticulously mask the work area off with plastic
- Move all furniture and other items out of the work area
- Ensure that you have professional respiratory protection gear
- Determine if you can use a wet sander to minimize dust creation
PRO TIP 3: According to Arthur Ross from Advanced Construction & Remodeling:
If you are going to dry sand concrete indoors (not recommended), then please do not skimp on dust-proofing your work area. Be very thorough when masking the area off. Have your vacuum system set up and make sure it’s working properly to keep the dust moving either outside the home or into a HEPA filtration unit. And please wear professional-grade respiratory gear. You only get one life!
STEP 4: Prep the Concrete Surface
Take your time with this step. First, clean all debris and stains off of the existing concrete to be sanded. If it’s new concrete with no stains or imperfections, then you’re good to go. However, if you need to fill cracks or holes, remove stains, or otherwise enhance the pad, this is the time to do so.
I asked veteran concrete restorer, David Peck from Impeccable Construction in Heath, Ohio, the best way to prep a concrete pad for sanding. He explained:
Clean the concrete with water and a stiff brush, and if it has tough stains that water can’t penetrate, try ammonia or hydrogen peroxide. After the concrete is sufficiently clean, allow it to dry very thoroughly. Hint: Fans speed up drying times.
STEP 5: Sanding and Polishing
Like sanding wood, sanding concrete involves determining the best grit to begin the process with. And remember that you don’t use traditional sandpaper for concrete sanding, you use metal-bonded diamond sanding discs. Non-diamond sanding products are typically not durable enough to withstand the abusive process of sanding hard concrete.
Be sure to carefully read the instructions that come with your concrete polisher or whatever other tool you’re using to sand with. Remember the old saying: If all else fails, read the instructions!
If you’re going to be sanding concrete that has scrapes, scuffs, and other anomalies, then you’re probably good to start out with a 40 grit grinding disc. Be meticulous when making your first pass, ensuring that you cover the entire sanding area from corner to corner.
Take your time with every move. Be thorough. Do excellent work!
After you make the first pass, stop and clean up. Run a vacuum, wipe up wet sanding slop, and restore the integrity of your work area. Cleanliness enhances safety and leads to a better finished product.
Now, move up to a finer grit number, like an 80 grit, and repeat the process. Then, step up to 150, 200, and then 400, if a truly polished surface is your goal. And on that note, you can purchase diamond sanding discs with grit numbers as high as 5000 (five thousand).
Of course, you can stop at any point of roughness you desire. It’s your concrete!
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STEP 6: Clean-Up & Apply a Hardener/Densifier
When you have achieved the degree of smoothness you want on your concrete, take some time to thoroughly clean the work area again. I can’t stress enough how important it is to maintain a clean and safe workspace. It truly matters in terms of staying healthy and delivering a top-notch product.
When the concrete is cleaned and very dry, apply a quality concrete hardener, sealer, and densifier according to the instructions provided on the container.
Sodium silicate in the hardener reacts with the free lime in the concrete to make calcium silicate hydrate, which subsequently acts to fill in the pores of the mix, leaving the pores completely sealed or at least smaller than they were.
This process significantly increases the hardness of the countertop, floor, sidewalk, or driveway, making it much more resistant to cracking, chipping, staining, UV harm, and other damage.
OK – TADA! You did it – you sanded, polished, and sealed your own concrete! That’s pretty badass!
Final Thoughts About Whether You Can Sand Concrete
Well, now, you know the answer is YES, you can sand concrete. I can’t stress enough the importance of developing and sticking to a good plan on every project, whether it involves sanding concrete or not. Every project ends up better with a good plan, thoughtful action, tidiness, safety, and meticulousness.
Thanks so much for reading along and learning about some of the nuances of sanding concrete. There are so many things you can do to save money relative to hiring a contractor. It just takes some learning, experimentation, and dedication to achieving professional-grade results, even if you hit a few speedbumps along the way.