The Ultimate Guide to Concrete Repair

Is your latest concrete job not all it's cracked up to be? Things happen. Even if you did a great job laying concrete for your latest client. Trees, weather, and other unforeseen circumstances can all take a toll on fresh concrete.

That's why it's important to know the ins and outs of concrete repair. It's easy for contractors to want to take shortcuts. There are always deadlines and budgets to meet. Getting things done faster usually means more money in your pocket.

It can also mean happier customers. At least for the time being. They may not be so happy when their new driveway starts to crack and settle.

Today, we're going to go over everything you ever will need to know about concrete repair. Whether it's from normal wear and tear, or because of poor workmanship, you'll be able to save the day when your clients come calling in need of concrete repair.

Let's get going!

Reasons for Concrete Repair

Concrete repair is just a part of life. All concrete has a certain "shelf life" to it. No matter how great of a job you do pouring your concrete, eventually there will be cracks. However, those cracks won't happen for a long time if you finish your concrete job the right way.

One of the best ways to repair concrete is to do everything you can to protect it from cracks in the first place. To do that, let's take a look at some of the reasons your concrete may crack.

Excess Water

If you put too much water in your concrete mix, you'll wind up with poor-quality concrete. Sometimes the water makes the concrete easier to install. Any excess water that is in your mix will cause the concrete to weaken after it cures.

Excess water in your mix can also lead to shrinkage of your concrete. A certain amount of shrinkage is natural as your concrete dries. But if there is excess water in your mix, your concrete will shrink more as this excess water evaporates.

Concrete can shrink as much as 1/2" per 100 feet. As it shrinks, the concrete literally pulls apart, causing it to crack.

Rapid Drying

Some contractors will attempt to speed up the curing process by putting a heat lamp or fan on their concrete. This is a big no-no. 

The curing process needs to happen naturally. The strength of your concrete relies on a chemical reaction between your mix and the water you add. This reaction can sometimes take several days or even weeks to complete.

If this is cut short at all, your concrete will not have the proper strength.

Lack of Expansion Joints

We don't see it with the naked eye, but concrete is actually moving. It constantly shrinks and expands with the weather. This constant movement can result in cracks if expansion joints aren't used.

Expansion joints are the black strips of "felt-like" material you see between pieces of the sidewalk. These joints give the concrete some room to move, which helps prevent cracking.

These joints should be equal to the depth of your slabs. They should also be installed no more than 2-3 times the depth of the concrete (in feet) apart. So, for example, concrete with a 4" depth should have expansion joints every 8-12 feet.

What You'll Need

The good thing about concrete repair is that you don't need too many elaborate tools. (most of the time). For small cracks that occur over time from natural events, you'll likely only need a chisel, hammer, and some new concrete or patching mix. You'll also need a trowel for spreading the concrete into the crack.

If you are doing a larger repair, however, you may need bigger tools to saw-cut sidewalk flags and so on.

The Concrete Repair Process

When it comes to how to repair concrete, there are a few simple steps to follow. The process isn't that difficult. It just takes time and effort. Fortunately for you, we're about to walk you through it step by step.

1. Chisel the Crack

To start the process, you'll want to take your hammer and chisel and begin to chisel concrete away from the crack. You'll want to use your chisel until you achieve an inverted "V" shape in the crack. Essentially, you'll want to use your chisel until the bottom of the crack is wider than the top. 

You'll also want to use the chisel to remove any chunks of old concrete. The "channel" you're creating out of your crack should be as clean and symmetrical as possible.

2. Remove Debris

You'll also want to remove any loose debris or pieces of old concrete. The crack should be as clean as possible for your new concrete or patching mix to do its job. 

Most of the time, you can do this by wiping away debris with a brush or damp rag. However, if there is a lot of loose sediment and debris, you may want to consider using a power washer. You can also use a yard hose with a power nozzle attachment.

3. Dry the Area

After cleaning debris with a brush or hose, you're going to want to make sure the area is dry to apply the new concrete or patch mix. Normally, these repairs need to be done as quickly as possible. Contractors don't have time to wait for mother nature to do its thing and dry the area naturally.

For that reason, most contractors will use a wet/dry shop vac to make sure the area is dry before moving onto the next step.

4. Mix Up the Mix

Now it's time to prep your new concrete or patching mix. It's important to follow the package directions when mixing concrete. If the proper proportions are off by the slightest bit, your concrete can lose its integrity.

This is also a major cause of concrete repairs. Contractors will pour a patio or sidewalk with poorly mixed concrete. As a result, the concrete is compromised and starts to crack and crumble more easily.

One of the reasons this can happen is because commercial concrete jobs are done with large batch mixers. It's hard to control the consistency of your product when it's mixed in such a large quantity.

This is an important step in the process, so if you need to take a little more time here, it will be worth it in the end.

5. Apply Concrete or Patch Mix

Now that our mix is ready, it's time to apply. You'll want to spread some concrete or patch mix onto your trowel and then neatly work it into your crack. Once your first layer of concrete mix is in the crack, you'll want to poke it with your trowel.

Repeatedly poking the mix will help to release any air pockets and prevents any air pockets and will make sure the concrete doesn't start cracking again. It may eventually crack over time, all concrete. But the idea here is to prevent this concrete from being compromised and cracking shortly after the repair is complete.

Once you've done a thorough job of preventing any future air pockets, you can take more concrete, mix and fill the crack up to the surface of the surrounding concrete.

6. Finish Your repair

No, we're not finished yet. When we say "finish" here, we mean make your repair look nice and neat. You'll want to smooth out the surface of your newly laid concrete mix with your trowel.

This is where you get to channel your inner artist! As you spread out your concrete mix, you'll want to use a technique called "feathering" to lightly blend the wet concrete into the surrounding dry concrete.

7. Texturing

This next step is completely optional, but it's another opportunity for you to be creative with the project. Depending on where the concrete repair is, you may want to input an element of creative texturing.

One of the easiest ways to do this is with a paintbrush. Occasionally, you will see sidewalk flags with this "texture" as well. It all depends on where you're doing the repair.

Do your best and do whatever is necessary to make it match the existing concrete as best as you can.

8. Curing

And now we wait. Once you've finished the installation process, you'll have to let the concrete cure. How long does it take? Well, that depends on the concrete mix you're using.

The package directions will tell you how long to wait to allow the concrete to cure. It's important to note that there is no way to rush this process. If the concrete is made to cure too fast or too slow, it will affect the quality of your concrete.

This is why contractors always make sure the weather is conducive to pouring concrete before they do any sort of concrete repair. The ideal conditions for mixing and pouring your concrete should also be outlined in the package directions.

9. The End

That's it! You're all done with your concrete crack repair. At this point, if you want to seal or paint the concrete, you can. It's a good idea to seal it to further protect it from the elements. But, other than that, you are done!

All It's Cracked Up to Be

Concrete repair isn't all it's cracked up to be. It doesn't have to be difficult, as long as you follow the instructions and take your time when you do the job.

If you have any questions on concrete repair or any other flooring questions, contact us at any time. The Onfloor team is always here to help and our experts can work with you to get you exactly what you need.