Learn how to fix minor cracks in concrete with a patch and find out when replacement is necessary Updated November 6, 2020
If your driveway, patio or other concrete surface has cracks, they can often be repaired. In some cases concrete crack repair can be a simple DIY project, in others it may require a professional concrete contractor to correct the damage and in the most extreme cases your concrete may need to be removed and replaced.
Find a concrete contractor near me.
Find crack repair products.
REPAIRING SMALL CRACKS
For minor cracking, here's how to fill cracks in concrete with a concrete patch or crack filler:
1. Chisel out the crack to create a backward-angled cut, using a cold chisel and a hammer.
2. Clean loose material from the crack using a wire brush, or a portable drill with a wire wheel attachment.
3. Apply at thin layer of bonding adhesive to the entire repair area using a paint brush. The bonding adhesive helps keep the repair material from loosening or popping out of the crack.
4. Mix vinyl reinforced patching compound, and trowel it into the crack. "Feather" the repair with a trowel, so it is even with the surrounding surface.
Wide crack variation
If the width of the crack is an inch wide or larger, the process of repairing cracks is slightly different. Chisel out the crack and clean loose material as listed above. Then pour sand into the crack within the surface. Prepare sand- mix concrete, adding a concrete fortifier, then trowel the mixture into the crack. Feather until even with the surrounding surface.
Tip: If you don't like the way your repairs look, consider concrete resurfacing for a fresh, uniform surface.
Featured Products
Concrete that is cracked only on the surface, or has hairline cracks where both sides of the crack are still level can be successfully fixed. See basics of concrete repair and troubleshooting
Cracked concrete should be replaced if due to the three conditions listed below. Any patching material used to fill these types of cracks will only be a short term fix. You definitely would not want to patch these cracks and then spend money resurfacing the concrete or doing a decorative topping.
Widespread, deep cracks, settlement has occurred
When concrete is cracked all the way through the slab it should be replaced. Sometimes this is due to the weight of large trucks, improper preparation of sub grade, erosion of sub grade, or other reasons.
- Remove the concrete
- Remove the sub grade
- Replace sub grade with compactable material (sometimes existing material is ok)
- Compact the sub grade
- Pour back concrete
Sunken concrete
Sunken concrete occurs when the sub grade was not prepared properly. Loose dirt may have been used for the sub grade. When this dirt settles-sometimes due to sprinkler or rain water going under the concrete- the concrete is unsupported and will be more susceptible to sinking.
It is possible that the sub grade was compacted and the concrete was subjected to extreme weight which caused the concrete to sink. This can often we fixed with special equipment that raises the concrete without damaging the slab (HMI Concrete Lifting & Raising Equipment).
- Remove the concrete
- Remove the sub grade
- Replace sub grade with compactable material (sometimes existing material is ok)
- Compact the sub grade
- Pour back concrete
Frost Heave
Frost heave is very common in cold climates. Moisture in the ground freezes and the concrete pushes upward.
- Remove the concrete
- Remove the sub grade
- Replace sub grade with compactable material (sometimes existing material is ok)
- Compact the sub grade
- Pour back concrete
Get the advice of a local soils engineer on sub grade preparation for your area and material needed to prepare sub grade (sometimes existing material is ok)
Whether you do the job yourself or contract it done-these are the steps to follow. See what is concrete and ordering concrete for information on ordering the right type of concrete
Other Resources:
Find a Concrete Contractor in Your Area
Find Concrete Repair Products
Skip to main content
Home House & Components Rooms Basement
Complexity
Cost
Fix the crack in your concrete garage or basement floor yourself by following these step-by-step directions.
- Concrete mix
- Concrete resurfacer
- Latex modifier
Using a diamond blade on your circular saw, cut a 1/2-in.-deep groove along each side of the crack. Wear an N-95 respirator and turn on a fan to blow the concrete dust out of the garage. Chip out the cracked portion with a maul and cold chisel.
Concrete cracks are caused by sideways expansion, poor drainage conditions or settling soil beneath the concrete. If your concrete is the same height on both sides of the crack, you can fix it yourself. But you have to enlarge the crack (Photo 1). Then power-wash the area and squeegee off the excess water before applying the concrete crack filler. Fill with a polymer-modified cement such as Quikrete concrete resurfacer No. 1131. Our crack was wide and deep, so we chiseled out the entire opening and refilled it (Photos 2 and 3). However, if one side of the crack is lower, call an expert to diagnose and fix the underlying soil/drainage problem. Then either replace the sunken portion or call a mud-jacking company to raise it.
Caulking Concrete Cracks
Cement Crack Repair: Remove the cracked concrete
Knock out the old stuff
Chip out the cracked portion with a maul and cold chisel. Remove the chipped pieces and vacuum out the crack before power washing.
Chip out the cut concrete to get a fresh surface so the new concrete can bond to it.
Concrete Demolition Tools and Tips
Complete DIY projects like a pro! Sign up for our newsletter!
Do It Right, Do It Yourself!
How to Repair Cracks in Concrete: Fill in the cracked concrete opening
Fill groove with concrete
Add latex modifier to regular concrete mix and pack it into the channel. Fill to within 1/2 in. of the original height. Let it set up for a few days, then fill with resurfacer. Establish a solid base for the resurfacer by filling the opening with concrete and letting it dry (see Photo 3).
Garage Floor Resurfacing: Fix a Pitted Garage Floor
How to Repair Cracks in Concrete: Add the resurfacer
Spread the resurfacer
Pour concrete resurfacing mixture into the crack and smooth it out with a rubber floor squeegee. Feather the edges to get the best appearance. Add water to the resurfacer mix to get the consistency of pancake batter for the concrete crack filler. Then fill the remainder of the groove and smooth it over.
How to Caulk Concrete
Originally Published: June 24, 2019