Over time, it’s not unusual for residential sidewalks to develop a few cracks or crumbles. To keep this damage from spreading too quickly, and to prevent potentially unsafe conditions, you’ll want to repair these problems before they get too big. This project guide offers steps and instructions on how you can repair those small cracks and crumbles yourself using just a few common masonry tools and a little bit of time.
New concrete does not stick well to old.
To anchor a patch make the crack wider at the bottom than at the top. Place a cold chisel in the crack, angle it slightly outward, and rap it with a 3-pound sledgehammer.
Clean out debris thoroughly with a stiff fiber or wire brush.
Crumbs and pebbles weaken a concrete patch.
Fill the crack with a patching mix - also known as vinyl concrete—made from vinyl, portland cement, and sand. It covers cracks up to 1⁄2 inch wide. Dampen the area around the crack, then trowel on the mix. Smooth the surface with either a trowel or a small float.
Pop-outs are small conical shape chunks of concrete that have popped out and left a hole behind. Using a cold chisel and a 3-pound sledgehammer, undercut the hole by making the pop-out wider at the bottom than at the top. Clean the hole with a stiff fiber or wire brush.
Wet the surface and apply a concrete bonding agent inside the hole with a paintbrush. Wait about 10 to 15 minutes or until it gets sticky.
Pack a small amount of anchoring cement into the hole and smooth the surface with a putty knife or trowel. Anchoring cement expands as it hardens. It is primarily used for anchoring bolts in holes drilled in concrete, but it also works well here. Keep the area moist until the patch cures.