How to repair cracks in concrete

How to repair cracks in concrete

If you own a property that has concrete flooring or you have a driveway or patio made of concrete, this guide is for you. Concrete cracks are something that starts small, but with time only enlarge. This is even more true to people who live in cold climates. in concrete.

All the cracks in concrete surfaces should be repaired before they get out of hand, so it is a good idea to know how to repair cracks in concrete. When a crack emerges it becomes inevitable that it will only get worse over time.

As debris, sediment, and water continue pushing through a crack in a concrete slab, the crack will become deeper and the surface will further separate exacerbating the problem. Add to this the fact that water will expand if it is allowed to freeze inside of a fissure and thus will cause further damage.

At worst, the water can freeze multiple times a day in a driveway for example and it will lead to concrete spalling.

Repairing cracks in concrete

By knowing how to repair cracks in concrete, a property owner will be able to avoid the costly replacement of a severely damaged slab by limiting the damage and shutting down the degradation process.

The repair process will begin with a general assessment to determine the extent of the damage. If the crack is minor, then it will be appropriate to fill.

If the crack is more severe caused by root growth or some other destructive process, then it may be necessary to remove a section of the slab, alleviate the destructive element, and replace the affected area.

Performing a surface repair to cracks in concrete that result from tree roots and the like will only last a short time.

How to succeed in repairing

To successfully accomplish a minor repair, the property owner will only need to know a few simple steps.

Remove loose concrete and clean the dust

The first thing to do is to chip away any loose material that may be hanging onto the fractured edges, and then thoroughly clear away all the debris and sediment that may have accumulated over time.

This can be accomplished with either high-pressure water or air being blown through the length of the damaged area. After this is complete, the area being treated should be allowed to dry out completely prior to applying a bonding agent.

Another way is to use a crack chaser angle grinder or skill saw and a crack chaser diamond blade, open the crack with a one-fourth inch wide by one-fourth inch deep minimum. Remove spilled or loose concrete pieces and vacuum this completely.

Both of the ways work, I usually combine them by using hammer and chisel to remove the loose concrete and sometimes angle grinder. After that I pressure wash it so it will be clean of all the dust, it’s more effective than vacuum.

Bonding agent on the crack

Once the preparations are complete, a bonding agent should be brushed into the crack that will provide the filler material with an appropriate surface to adhere with.

Patch the crack

There are multiple ways to fix the cracks and they have different pros and cons like always. Here I’ve got using patching compound and silica and polyurethane/epoxy.

Polyurethane is good for small cracks as it fills the cracks and stops the water from going in and doing harm. Epoxy does the same but is stronger so it can be used for bigger cracks with silica sand.

Now both of these are good ways to fix walls and floors that might have water on them like basements.

Patching compounds come in multiple forms and from multiple manufacturers as well. It’s good to see the manufacturer’s label to see what they promise. I have no input which is better as it always depends on the situation and the place you’re fixing.

The best practice is to comfirm what you’re dealing with and go to the hardware store or professional for how to fix it. Just remember, there are multiple ways.

Repair spider cracks in concrete with polyurethane and epoxy
Patching compound

After the crack is cleaned, a patching compound can be troweled into the crack making sure to avoid leaving any air pockets or unfilled areas behind. The entire fracture should be filled in one application to avoid having unnecessary cold joints in the slab.

With the filler in place, the surface can be troweled smooth or given a brushed finish that will match the texture of the existing slab. If you have a smooth slab, you can use different kinds of floats to match the surface.

If there is rough float circles, sponge float might work. If it’s just smooth, some sort of rubber float might do the trick like they use to push grout into tile seams.

It’s important to follow the manufacturer information on how to mix the concrete patching compound and how to apply it. That way you will have the best result.

Silica and polyurethane/epoxy

Fill in the cracks using silica for added strength and in order for the prevention of filler from disappearing under the crack. Now, this only works easily with floors, for walls, some extra tricks will have to be used or the sand will just fall off and the same will happen to the polyurethane/epoxy.

Next, you mix the polyurethane or the epoxy filling material. Then pour or inject the filling material into the crack and give it time to settle. Top up sagging areas and add more sand if needed.

Scrape, sand or grind off the excessive material in order to leave a smooth concrete finish.

If you’re trying to fix walls like this, using construction sealant with a caulk gun might help you. Seal the bottom of the crack with it and inject the polyurethane/epoxy on top of that. Once the polyurethane/epoxy gets hard, remove the construction sealant from the surface as it looks ugly.

Also, if someone gets the idea here to use construction sealant on the cracks, don’t do that if you don’t want water damage. I’ve seen way too many people and even construction professionals try to fix cracks like that and I’ll tell you what it will do.

If the water is coming from the outside, it will slowly eat the concrete around the construction sealant until it becomes so weak you can drop it away with small taps of a hammer. The proper way to fix this kind of damage is way better and it looks better.


Now you should have some guidelines on how to repair cracks in concrete. It is not as difficult as it may look at first glance. The entire process can be completed in a relatively short period of time and will reduce the possibility that further damage will occur causing much greater expense to the property owner.

If you have polished concrete floors, you can follow this guide on fixing the cracks.

By knowing how to repair cracks in concrete, the property owner will halt the degradation, improve the functionality of a slab, and avoid more costly repairs or replacements that are likely to be required if the damaged slab is left unattended.

Now if you don’t want to handle it yourself, it’s always possible to call someone who does it for living to fix the situation. Just make sure they are proper professionals and not just some people pretending to be.

A sign of a professional is that s/he can explain the process to you so that you understand what is going to be done. That shows s/he understands it as well and facts can be checked.