How To Sand Concrete

How To Sand Concrete

Concrete has been used throughout history – from the ancient Rome arena up to the modern-day buildings. It plays a vital role in the overall construction of different cities. Most of our office buildings and homes nowadays are made up of concrete. That is why getting and maintaining a smooth concrete surface is important for many of us. 

Sanding a concrete is one of the ways you can give your concrete a more polished and clean look. It can also make your concrete surface look like expensive natural stone materials. This is also a process of resurfacing an old concrete floor or building. 


Why should I sand my concrete floor? 

If you have an old concrete floor that needs resurfacing or just a little polishing to make it look fresh and new again, then sanding is a method that you may want to consider. Aside from a more polished look, there are many reasons why homeowners sand their concrete:

  1. You have decided to cure, finish, or paint the exterior of your concrete.
  2. Your concrete floor is rough or uneven that it needs some polishing.
  3. Your concrete floor was poured poorly that it needs some correction.
  4. You want to smooth out the surface of your concrete floor.

There are countless reasons people resort to concrete sanding but regardless of their reason, the method is almost the same. 


How To Sand A Concrete By Hand 

Hand sanding is ideal for polishing a counterpart or small surfaces. In this method, you will be using sandpaper, hand grinder, or random orbital sander. Since this is manual work, it takes some patience, but the result is beautiful. 

The most common and the easiest hand finish is a smooth finish or scuffing. Scuffing refers to the process of scraping or brushing off the surface. 


Tools Needed: 

  • Diamond sanding pads 
  • Concrete polisher or angle grinder 
  • Patching slurry (same shade as your concrete)
  • Sponge or squeegee


Step By Step Process: 

  1. Clean out the surface to remove any debris that might cause small holes. 
  2. Specified the type of finish that you want. Measure and mark the depth on the edge of the surface. Examples: 1/16, 1/8, or 1/4 inches. 
  3. Check if there are any holes or pit in the concrete surface. 
  4. If you found holes, fill it with a patching slurry. 
  5. Sand the entire concrete surface using the coarsest grade of sandpaper. Manage to keep your pressure even.
  6. If you are using a grinder, make sure that it is leveled to prevent uneven results. Remember that concrete polishers need a constant supply of water for a great outcome. 
  7. Using hand pads, reach the spots that the grinder can’t reach. 
  8. Wipe the concrete surface using a sponge to remove any debris. 
  9. Use the next finer grade of sandpaper for a more polished result. 
  10. Wipe the surface again using a sponge to get rid of the small particles. 
  11. Rinse the concrete surface with water. 
  12. Repeat the process if necessary until you get the desired result. 
  13. Allot time to let the concrete dry. Since concrete is porous, give it one to two days to dry. 
  14. Apply a concrete sealer for a more polished look and more protection. 

A floor sander is used when you are sanding large concrete spaces. When you are working indoors using a sander, it is recommended to sand the entire part, because using it on a certain spot can result in discoloration on the other parts of your concrete. 


Tools Needed: 

  • Duct tape
  • Epoxy resin
  • Floor grinder or pole sander 
  • Mop 
  • Plastic sheeting
  • Protective gear (face mask, goggles, earplugs, rubber gloves)
  • Shop vacuum 


Step By Step Instruction: 

  1. Prepare the work area by removing all the furniture in the room 
  2. Install your protective coverings. Cover any wall, doorways, vents, or other surfaces with plastic sheeting to prevent dust from spreading and sticking. 
  3. Clean the floor by mopping it.
  4. Allow the floor to dry after mopping.
  5. Create a partition or zones to focus on one section at a time while working. 
  6. Start working in one corner using a 30 to 60 grit sandpaper. 
  7. Move with the next sections of the floor. 
  8. Make additional vertical passes. 
  9. Gently sand over bumps with repeated passes until they are even or smooth. But refrain from leaving the sander stationary. 
  10. Check for any cracks or pits and fill them with epoxy resin. 
  11. Allow the epoxy to dry. 
  12. Have another round of passes, starting from the corner where you ended back to the starting point. 
  13. Make multiple sets of passes, this time running horizontally in both directions.
  14. Wipe the floor with a clean sponge, rag or mop to remove any debris. 
  15. Apply an even coat of concrete sealer. Don’t forget to read and follow the instruction on the product label.  
  16. Use an 80 or 120 grit sandpaper while repeating the steps.
  17. Wipe clean the floor again. 
  18. Switch to finer grit sandpaper for a smoother, polished look. 
  19. Keep on repeating the steps above using finer grit sandpaper. Made several passes gently until you reach the industry ideal of 1,500 grit. 
  20. Mop or clean occasionally while making some passes to get rid of unnecessary dust. 
  21. Seal it with a paint of sealant for a more polished appearance.