How do I Repair Concrete?

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  • Written By: Nychole Price
  • Edited By: Bronwyn Harris
  • Last Modified Date: 13 September 2019
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Concrete is notorious for cracking. This can be caused by changing weather conditions, the ground shifting or something heavy dropping on the concrete. Whatever the reason, you must repair concrete before the crack spreads. To repair serious damage to concrete, you'll need to remove the damaged section, undercut the edges of the area, and fill the hole with a new cement mix.

Safety is always the first step in the process to repair concrete. Always wear eye protection, as concrete tends to crumble and the tiny pieces can cut your eyes, causing permanent damage. It is also recommended to wear gloves to prevent smashing your fingers or cutting your hands.

Start the process to repair concrete by removing the damaged cement around the crack. Use a hammer and a large chisel to chip away the broken, crumbled and disintegrated concrete. You should have a somewhat round hole, about an inch (2.54 cm) in depth, after all the damaged concrete is removed.

The next step to repair concrete involves undercutting the edges of the area you have chipped away. This is done by widening the bottom of the hole, but leaving the top untouched. The result will be a hole with inside walls that slant inward as they go up.


Removing all the chipped concrete and debris from the hole is the next step in concrete crack repair. It is easiest to do this with an industrial vacuum, as you can be sure to get all the dust and small pebbles. Moisten the hole with water every couple hours for a full day.

It is now time to mix the concrete in two separate batches. The first batch is mixed a little thick, at a ratio of 3 parts cement to 1 part water, so that it resembles paste. The next batch is mixed slightly thinner than the first batch, but still thick enough that it can coat surfaces. Use the second batch to quickly coat the inside walls of the hole before it dries. Now fill in the hole with the first batch of cement.

Allow the cement to dry for a few hours. When the time has passed, cover the fixed areas with plastic wrap. Use a spray bottle to moisten the area a few times per day for a period of one week. After the week has passed you can remove the plastic wrap and the area should be as good as new.

If there are large amounts of cracks in the concrete, it may be best to replace the whole concrete pad. You can use a jack hammer to break up all the concrete and cart it off in a wheelbarrow. Follow the instructions on the bag of concrete for laying a new pad.


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Discuss this Article

Post 4

@gravois - You can probably handle the project yourself if there are only a few cracks covering a small part of the patio. If the cracks are bigger you may want to call in a professional to replace the entire thing. I've done a concrete slab repair using the method described above and the process was pretty easy and painless. The patched area looked a little different than the rest of the slab but the damage was gone and the patch held up for years. Give it a shot. You would be surprised how much you can do yourself.

Post 3

I have some cracks in my backyard patio that I have been wanting to get fixed for years. The explanation above seems simple enough but I wonder is anyone out there has any experience doing this kind of thing? Is it a project that an amateur could realistically handle themselves?

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