Concrete crack repair

LAST UPDATED: 8th January 2023 by The Editorial Team

Concrete crack repair

Summary: Step by step guide and video showing how to repair a concrete crack using a patching compound.

How to repair concrete

It is always important to prepare well when repairing damaged concrete. Before you start mixing the solution to use on the cracks, you must consider the best way of preparing the area to be worked on. Cracks or holes in concrete paths or driveways can either be holes that need filling, or depressions that need to be correctly supported underneath to prevent further depressions in future.

If the subsurface is not as dense in one area as it is in another, this will be the cause of a depression in the concrete. This needs to be recognised and dealt with by filling in the weaker patches of subsurface with strengthening material to avoid the same problem occurring again.

Repair concrete crack

  • If the crack has thin tapered edges you will want to use a hammer and chisel to chip away the edges of the crack. Remove as much as necessary until you are left with solid, thick concrete edges. Always use goggles when chiselling concrete.
  • To mix the patching compound that you will use for filling in the crack, you must ensure that it is the correct material for the job, and that the instructions are clear to follow, so you do not mix something too weak. You will want the consistency to be a thick paste.
  • With water based repair compounds you will firstly need to wet the surface of the area you will be filling.
  • Depressions or deep cracks will probably need to be reinforced with nails or pieces of reinforcing steel. This will help hold the concrete firm so depressions don’t occur again in the same place. Make sure any reinforcing material used in the depression is at least 1/2 inch below the surface.
  • Using a float or other similar tool spread the compound onto the area you are repairing. Make sure it fills the crack properly. You may want to practise the technique elsewhere beforehand.
  • When finished, lay a plastic sheet over the area and add weights onto the sides of the sheet so it is not disturbed. It is important the new concrete repair is not disturbed or allowed too much air. Leave to set in this way for three or four days.

Tools needed

  • Hammer
  • Chisel
  • Goggles
  • Float
  • Trowel

Materials needed

  • Concrete patching compound
  • Plastic sheet

Repairing concrete video

Author

The Editorial Team

The Editorial Team at lets-do-diy.com are a team of experts led by Mark Wilson. We have been creating DIY projects, articles, costs guides and product reviews since 2008. For more info see our about page.