How to Repair Cracks in Concrete Floors

By
Jeff Beneke
Jeff Beneke
Jeff Beneke is a home renovation expert. A self-taught carpenter, cabinetmaker, electrician, and plumber, he has renovated two 19th-century farmhouses in upstate New York and a mid-20th-century house in Austin, Texas. He has written more than a dozen books related to home renovation, repair, and maintenance and contributed to another dozen.
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Updated on 08/25/21
Worker kneeling and filling in concrete on the floor.

Peter Muller / Getty Images

Project Overview
  • Working Time: 1 - 2 hrs
  • Total Time: 1 day
  • Skill Level: Beginner

Tough as it is, concrete tends to develop small cracks and chips. Minor problems like this generally do not indicate any structural problems that require resurfacing, but it is best to tend to cracks as soon as possible. Once a small crack or chip appears, future wear and tear will only cause it to expand. Here's how to fill a crack between 1/4- to 1/2-inch wide.

Before You Begin

To ensure your repair work holds well, the area must be very clean. With a wire brush, clean the crack. Sweep away any loose debris, then vacuum the crack. If grease, oil, or dirt remains in or near the crack, clean it thoroughly, or you might find that the repair won't hold.

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What You'll Need

Equipment / Tools

  • Wire brush
  • Vacuum cleaner or shop-vac
  • Cold chisel
  • Hammer
  • Safety glasses
  • Trowel
  • Paintbrush

Materials

  • Concrete bonding adhesive
  • Sand mix

Instructions

  1. Undercut the Crack's Edges

    Once the area is clean, use a cold chisel and large hammer to undercut the edges of the crack. This will help hold the patch in place. Be sure to wear eye protection.

  2. Apply Bonding Adhesive

    With a small paintbrush, coat the crack surface with concrete bonding adhesive. Allow the adhesive to dry completely.

  3. Prepare the Sand Mix

    Mix a suitable amount of sand mix with water as instructed on the bag. (Sand mix is one variety of dried concrete products sold in bags at home stores.)

  4. Fill the Crack

    With a trowel, fill the crack thoroughly with the mixture. Smooth it down with the side of the trowel and level the surface as much as you can.

  5. Let the Patch Dry

    Allow the patch to cure undisturbed as instructed on the bag.