November 3, 2023
This page will teach you how to fix cracks in concrete floors, slabs, patios, and concrete driveways.
Let's face it, cracks in concrete floors are quite common. But, knowing how to repair a concrete crack isn't common knowledge.
I'm going to share with you my easy step by step guide for fixing cracks in concrete. This guide will work for all types of concrete flat-work (floors, slabs, driveways, patios, and pool decks).
Here's a list of the tools you'll need to fix your cracked concrete.
You'll need a way to smooth out the repair material once it is dry. I prefer the 4" hand grinder with a diamond cup wheel.
You can use a rubbing stone or a palm sander if you want, it's just not as fast and takes a little more effort to smooth out the repair material with these tools.
When I repair cracks in concrete like the one in the picture above, I always use CrackWeld Concrete Floor Repair Kits from RadonSeal.
I buy the PRO KIT Duel Cartridge's because my company, Day's Concrete Floors, Inc specializes in concrete crack repair.
If you buy the PRO KIT, it comes with that duel cartridge caulking gun. If you buy the diy CrackWeld kit, you use your own caulking gun and use a single cartridge at a time.
You use the same methods and same techniques with each kit to produce the same results.
CrackWeld is a 2-part polyurea repair material. When you eject the material out of the cartridge and through the mixing nozzle into the crack, it quickly reacts and cures rock hard.
You don't need to widen or "chase out" the crack. The repair material bonds with the sand to form a "concrete like" mass inside cracks, spalls, and holes.
Water, vapor, or other liquids and gases can not penetrate it. It's also considered a structural repair material, it will stop a crack from any further movement.
Assuming the concrete floor thickness is 4 inches:
If the crack is 1/16 inch wide:
If the crack is 1/8 inch wide:
If the crack is 1/4 inch wide:
IMPORTANT: The inside of the crack must be clean and dry!
If you don't want to use a diamond grinder:
Here's a PDF guide for the DIY Concrete Floor Repair Kit.
You can Download the installation instructions and cartridge assembly guide.
This guide shows you how to put the cartridge, backflow restrictor, and mixing nozzle together. (these instructions come with the kit also)
It also has the basic instructions for repairing a crack.
I would definitely recommend watching the video. You know what they say, if a picture is worth a thousand words a video must be worth a million.
If you're concrete floor has a hairline crack, you won't need the sand to repair this one.
Just make two passes with the CrackWeld resin and that should be enough to fill and repair the crack.
Use the putty knife to push any excess resin into the crack if you need to.
After about 20 minutes, sand the excess resin off the floor.
When I fix a crack in concrete that's larger than 1/4 inch wide: After I vacuum out the crack, I always pour some dry silica sand into the crack first, filling the crack to about 1/8 inch below the surface of the floor.
This keeps the CrackWeld resin from just running out of the bottom of the crack. Then follow the instructions in the guide above starting with step 2.
YES, to fix spalled concrete:
YES, to fill holes and chipped areas of concrete
Only mix small amounts at a time, you will only have about 5 - 10 minutes of working time.
CrackWeld concrete crack repair can be used for:
YES, after you grind or sand the crack repair material smooth, you can paint, epoxy, or use a concrete overlay material over it.
NO, CrackWeld is a rigid crack repair material. It dries very hard. Do not use it to repair expansion joints or floor to wall joints. It's not for joints that require some sort of flexibility.
For repairing joints that require flexibility you can use RadonSeal's Elastipoxy Joint and Gap Filler Kit.
If you live in an area where you have freeze/thaw cycles and you have exterior concrete with some cracks you want to repair:
Like in a concrete driveway, pool deck, or patio.
Then I recommend you use Elastipoxy to repair the cracked concrete.
Elastipoxy will allow for some movement of the concrete (it dries flexible) without breaking down.
It's a very strong 2-component, 100% solids, flexible, AND self-leveling crack repair product. (making it easy to install)
Unlike some of the "big box stores",
CrackWeld has some very good advantages: "This is why I use it"
"There's absolutely no comparison, don't waste your money on the "big box" store's crack repair products. Take it from a pro, RadonSeal's CrackWeld will get the job done as advertised."
YES I want the diy CrackWeld repair kit. (You'll go to RadonSeal's page)
YES I want the CrackWeld PRO kit. (You'll go to RadonSeal's page)