Repairing cracks in polished concrete floors

Repairing cracks in polished concrete floors

Do you have a beautiful polished concrete floor but with some of the floors little cracks can be noticed? Or maybe you have an old concrete floor that has served well so far, but lately, you’ve started to notice some cracking?

It can be annoying when you have a beautiful polished concrete floor, a pleasure to walk on, but you notice cracks that break the harmony. You start to feel a little annoyed as you can imagine what it will cost to have professionals repair that if you don’t have a warranty covering it.

No need to stress as with this guide, you can repair those unsightly cracks without the need to hire expensive repair people. Or go through the process of finding a good one.

One factor to keep in mind is that repair products will not eliminate the crack, but minimizes the unsightliness of these cracks and prevent further cracking. A good repairing product will help you to stop the expansion of the crack if it’s not a structural problem or some other one like that.

Major cracking may and probably will require the services of professional concrete repair people, but save time and money on the smaller ones by completing the repairs yourself.

Repairing the polished concrete crack

Repair starts by cleaning crack areas thoroughly and examining the size and width of your cracks. Every concrete crack repair begins like this as you need to know what you’re working with.

If there is loose concrete use a hammer and chisel to remove them and vacuum to clean the dust off. You want the crack as clean as possible because that will guarantee the best adherence. With concrete repair, that’s the most important step really as weak adhering will spoil the fix.

Research the polished concrete repair products to find correct one for your floor

Time to select repairing materials

Once you determine the extent of repair required, you can gather the necessary repair materials. A product such as a good concrete mender is needed for repair. For small cracks that are most often something made of polyurethane or epoxy.

The reason for that is that they are easy to inject into the smallest cracks and they adhere well to the crack’s inner surface. It will glue the crack together and stop it from expanding most often.

Choose a combination of filler products for the cracks. Suggested materials are glass, flint, or silica sand and should be dry and free of other contaminating materials such as dirt.

Why not go with fully injecting with polyurethane and epoxy? If the crack is deep or wide, some filler will make fixing it less expensive. I’ve used silica sand a lot with polyurethane and epoxy flooring and I can say it adheres well to both. For polished concrete, you will probably need more than one kind of sand.

Blend the color to match the floor

The challenge in using such a product is to blend the color with sand that will match as close as possible to the concrete color being repaired. You may need to experiment with colors and sand blends to find the color combination that will match the overall color of your floor.

I advise taking your time with this as it is the key to the success. You will be repolishing this so doing a good blend will make a huge difference in how much of the repair can be seen.

Time to fill the crack

Concrete mender requires careful mixing of mending product with filler products, to the proper ratio according to the manufacturer’s instructions.

Use a trowel to fill the cracks making sure the repairing material is a bit higher than the actual floor surface. This is because you will be polishing this, if the repair is lower than the rest of the floor it’s not going to work the way we want. It will still look like a crack.

Be extremely careful not to stain the area around the repair with the dye being used for repair. It’s good to use tape and plastic or cardboard to protect the surroundings as much as you need. Just remember to remove the tape when you’re done as the epoxy or polyurethane can stick hard.

Wait until it’s dry

You need to wait now until the repaired area is completely dry. The drying time will depend on the size of the repair, the temperature of the floor, and the room. Once the material is dry, you can then hone and polish the area carefully.

A good way to know more about this is by reading the manufacturer’s info, which will tell you how long it usually takes. There’s no harm in waiting for a little extra so let it be to be sure, it’s not going to go anywhere.

Polishing again

For re-polishing area, use a planetary polisher. Use the most coarse sandpaper grit on the repaired surface. You will work to finer grits slowly as you go.

Go over the area repaired with overlapping motions but use caution that the focus is on the repaired area. You don’t want to polish the surroundings of the crack too much until you get closer to the finest grit.

Use a finer grit of sandpaper to polish the repaired area and the overall area to the blended desired sheen. Repairs do not have to be expensive, but careful work is required to ensure your repaired areas blend into the overall beauty of your floor.


This was a short guide for repairing cracks in polished concrete floors, it’s meant to show the general direction as concrete cracks can be as different as the polished floors and the products used to fix them.

For small cracks, the repairing shouldn’t be too difficult and it gets harder the wider they become. In the end, if the cracks get so wide you become worried, you won’t be searching for fixes for it but for the slab itself.

One thing with the cracks is also that the bigger they become, the harder they are to fade. Small hairline cracks can be a good thing as well as some enjoy the look. But with the wider ones, it gets harder to see them and harder to fade them when you fix them.

That is because, it can be hard to match some colors and if there is staining or colored concrete, it is even more so. But, you don’t have to mind it too much. Fixed concrete is still better than damaged one as it will provide protection from extra damage.

Also, if the floor is full of little cracks and you have to do many small repairs, consider using a concrete floor leveling compound for making a new top layer for the floor.