How to Repair Wide Cracks in Concrete

a crack in the concrete
••• coun2rparts / Flickr CC 2.0

The techniques used to repair concrete will depend on the location of the crack and how big the crack is. Concrete cracks repairs must be done carefully to prevent additional consequences and further deterioration. The recommended technique for patching cracks will also depend on the surface being worked out and whether the crack will be visible or on a walkable surface.

Corner cracks typically due to drying shrinkage, thermal movement or other causes usually are minor and result in few problems. More often than not, a foundation crack will widen over time and result in water seepage or possibly the loss of structural integrity. Always consider whether the crack is structural, aesthetic or you just need crack sealing. Let's see how concrete can be repaired.

How to Repair Wide Concrete Cracks

Repairing wide concrete cracks sometimes requires precision and skillfulness. A wide crack in concrete should be undercut using a small sledgehammer and chisel. Widening the crack should be the first step creating a keyed surface where the concrete patch can be placed, and a more secure and reliable repair could be made.

  • Now that the concrete crack has a wider base remove all debris using a wire brush, a damp cloth or a vacuum to remove small particles that will prevent the adhesive from bonding to the concrete surface.
  • Mix the concrete patching compound that will be used to repair concrete cracks. Remember that each product contains specific instruction from its manufacturer. Once the concrete patch is mixed, trowel the compound into the cracks. Begin by tamping the mixture to remove air pockets that might between the concrete surface and the patching compound. 
  • Finish the patching compound that has been used to repair concrete. Smooth the mixture with the trowel, and wait until the patch has set. Once the patch has set, smooth or brush the surface to match existing surface.
  • After patching the concrete, it's a good idea to seal it. Concrete easily absorbs stains, and sealing will prevent that. There are many products available for concrete sealing, but heavy-duty water-based polyurethane is a good choice.

Note: Small particles will be flying into the air, so it is very important always to wear PPE.

How to Repair Narrower Concrete Cracks

Repairing narrow concrete cracks is easier than repairing wide cracks if, and only, the recommended products are used. Howe

  1. Start by removing any loose debris from the concrete crack that will be repaired. Using a wire brush and broom remove all dust and paint from the surrounding concrete surface. Rinse the area using a hose or a bucket of water. Let it dry.
  2. Narrow concrete cracks can be filled using masonry crack elastomeric filler that could be applied using a caulking gun. However, small concrete cracks, or hairline cracks, could also be repaired using a vinyl concrete patching compound applied over the crack and then smoothed with a putty knife. Sometimes additional steps are needed, especially when concrete is adjacent to other products and the joint itself is the one presenting a crack.
  1. If you have selected vinyl concrete patching compound to repair the crack, you can avoid applying a bonding agent over the concrete surface.
  2. Hairline cracks can be repaired using manufacturer injection kits, making it easier to apply the product inside the crack. Do not apply caulk only, over the crack as it will eventually show up again.

Other Options to Repair Concrete Cracks

As mentioned before, there are many ways to repair concrete cracks. Some of the other options available to you are:

  • Epoxy injection,
  • Dowel installation on larger cracks
  • polyurethane injection,
  • Dry packing,
  • Concrete overlays and micro-toppings,