Concrete Crack Repair: How To Fix Cracks in Concrete
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Cracks in concrete are a common problem that can affect everything from your driveway to your garage floor and even the sidewalk outside your home. Over time, these cracks can widen, allowing water and debris to penetrate. This in turn can weaken the concrete slab and cause more serious issues. Whether it’s hairline cracks or larger gaps in old concrete, knowing how to address them is crucial for maintaining the appearance and structural integrity of your concrete surfaces.
In this blog, we will walk you through everything you need to know about how to fix cracks in concrete. Whether you're dealing with small cracks or looking to patch up larger damage on existing concrete, we hope this guide will be enough. By following these steps, you can restore your concrete surfaces and prevent further damage, keeping your house looking its best while saving money in the process. Let’s dive in and tackle those cracks for good!
Before diving into concrete repair methods, it's important to understand the different types of concrete cracks you might encounter. Not all cracks are the same, and the way you fix them can depend on their size and cause. Here’s a quick breakdown:
These are very small, thin cracks that often appear on concrete surfaces over time. Hairline cracks can be caused by natural shrinkage as the concrete dries or minor temperature changes. While they might seem insignificant, sealing them early with the right sealant can prevent them from growing larger and causing bigger problems.
Narrow cracks are a bit wider than hairline cracks but are still generally under 1/4 inch wide. These cracks can form due to minor shifting of the concrete slab or from changes in the ground underneath. For these types of cracks, you can often use a concrete crack filler or caulk to fill the gap and seal it off.
Wider cracks or voids are typically more serious and may require a bit more work to fix. These cracks can form due to more significant movement in the concrete slab, poor installation, or even air pockets left behind during the pouring process. For these larger cracks, you may need to use an epoxy or polyurethane filler along with a backer rod to fill in the deeper spaces before applying the repair material.
Control joints are intentionally placed in concrete driveways, garage floors, and other large concrete surfaces to help control where cracks might occur. Sometimes, however, cracks can extend beyond these joints. If that happens, it’s important to fill them properly to prevent further spreading while maintaining the integrity of the existing concrete.
Before you start fixing any concrete crack, proper preparation is key to ensuring a long-lasting repair. Taking a little extra time in this stage can make a big difference in the final result. Here’s how to get your concrete surface ready:
To make the repair process smooth, you’ll need a few basic tools and materials:
Make sure you also have the right repair material on hand, like epoxy, polyurethane, or a concrete patch product. Having everything ready will save time and make the job easier.
Cleaning the crack is one of the most important steps in the process. Use a wire brush to scrub away any loose concrete, dirt, and debris from inside the crack. Follow this up with a blower or pressure washer to remove any remaining dust or small particles. The cleaner the crack, the better the crack filler or patching material will bond to the existing concrete.
Next, check how deep the crack is. For deeper cracks, using a backer rod can be a smart move. A backer rod is a foam insert that fills up space in deep cracks, allowing you to use less filler and create a stronger bond. Insert the backer rod into the crack so that it sits just below the surface before applying the repair material.
Choosing the right repair material depends on the size and type of crack. For small cracks, caulk or a self-leveling concrete crack filler may be all you need. For larger gaps, an epoxy or polyurethane might provide a more durable solution. Be sure to read the instructions on your chosen repair material to ensure the best results.
Now that your concrete crack is cleaned and prepped, it’s time to repair it. Don’t worry—this process is simple and can be done with just a few basic materials. Follow these steps to get your concrete surfaces looking smooth and secure again:
After preparing the area, do a final clean-up of the crack with a blower or a dry brush. This will ensure there’s no dust or debris left behind, which can prevent the repair material from sticking properly. For deeper cracks, make sure the inside is free of any small pieces of loose concrete.
For narrow cracks that are deeper than 1/4 inch, use a backer rod to fill most of the space before applying your crack filler. Simply push the foam rod into the crack until it’s just below the surface of the surrounding concrete. This will help you use less filler and create a better seal.
Now it’s time to fill the crack with your chosen repair material. Here’s how:
Once the filler is applied, use a putty knife or trowel to smooth out the surface. This step is important for creating a clean, even finish. Make sure that the repair material is level with the existing concrete so that the crack blends in with the rest of the concrete surface.
Different repair materials have different curing times, so be sure to check the instructions on the product you’re using. Typically, you’ll need to let the repair sit for 24 to 48 hours to fully harden. During this time, try to keep the area dry and avoid walking or driving on it if it’s on a concrete driveway or garage floor.
Once you've filled in and smoothed out the concrete crack, the job isn’t quite finished yet. Properly curing and sealing the repaired area is essential to make sure your work lasts. This step helps the repair material bond strongly and protects the surface from moisture, weather, and wear. Here are some steps you can follow:
After applying the crack filler or patching material, you’ll need to let it cure—or harden—completely. This process can take anywhere from 24 to 48 hours, depending on the product you used and the weather conditions. Make sure that you following the below steps:
A proper cure helps ensure that the repair material bonds tightly with the existing concrete and prevents future cracks from forming.
To give your repaired concrete extra protection, use a concrete sealer. Sealing the surface can help keep out moisture, prevent future hairline cracks, and maintain the appearance of your concrete surface. Here are some tips on how to do it right::
To keep your concrete surface in great shape, it's a good idea to check for any new cracks or signs of wear every few months. Regular maintenance can help extend the life of your concrete driveway, sidewalk, or garage floor. If you see any small hairline cracks forming, you can apply a sealant or caulk quickly to prevent them from spreading.
Repairing concrete cracks yourself can save you money, but like any DIY project, it can come with its own set of challenges. Here are some common issues you might encounter while repairing concrete surfaces and tips on how to handle them:
One of the most crucial steps is making sure the crack is free of loose concrete, dust, and debris before applying any repair material. If you don’t clean it well, the crack filler may not adhere properly. Here’s what to do:
A clean crack means the repair material will bond better, resulting in a more durable repair.
Sometimes, after applying a crack filler, you might notice that it sinks below the level of the surrounding concrete once it starts to dry. This can happen if the crack is too deep or the filler isn’t applied properly. In this case, if you have deeper cracks, it is better to use a backer rod before applying the filler. This helps to fill in space so that the filler doesn’t sink. If the filler has already dried and sunk, you can add another layer on top to level it out. Using the right amount of repair material and allowing it to settle before adding more can help you avoid this problem.
After repairing the crack, you might notice that the patched area looks different from the surrounding concrete. While this won’t affect the strength of the repair, it can be an aesthetic issue, especially for visible areas like a concrete driveway or sidewalk. To avoid this:
It’s possible that after fixing one crack, new ones might appear nearby, especially if the underlying issue hasn’t been addressed. This can happen if there’s ongoing movement in the soil beneath your concrete slab or temperature changes. To prevent this:
For concrete driveways, it’s important to use a crack filler that can handle weather changes and heavy traffic. Polyurethane sealants and epoxy fillers are popular choices because they are durable and flexible. For small cracks, a self-leveling crack filler can be effective, as it smooths out easily and resists moisture.
Hairline cracks are typically less than 1/16 inch wide, but they can still let in moisture, which can cause bigger problems over time. To fix them, clean the crack thoroughly and apply a thin layer of concrete sealant or caulk with a caulking gun. Make sure to smooth it out with a putty knife for a neat finish.
Both epoxy and polyurethane are great options for filling larger cracks in concrete slabs. Epoxy is rigid and works well for cracks where there’s little movement, like in a concrete floor. Polyurethane is more flexible and can handle slight shifts, making it better for outdoor concrete surfaces that may expand and contract with temperature changes.
The lifespan of a concrete sealant can vary based on the product and the environment. Generally, sealants last between 3 to 5 years before they need reapplication. For high-traffic areas like a garage floor or driveway, you may need to reapply more frequently to maintain a protective barrier.
It’s best to repair concrete cracks when the temperature is between 50°F and 85°F, as this helps the repair material cure properly. If you must do a repair in cooler weather, use products designed for cold applications, and follow the instructions closely. Keep in mind that sealants and crack fillers may take longer to set in lower temperatures.
To prevent cracks in new concrete, ensure that it’s poured properly and that control joints are placed at the right intervals to guide where cracks may form naturally. For existing concrete, regularly apply a concrete sealer to protect against moisture. Keeping heavy loads off the concrete surface and maintaining stable ground underneath can also help prevent future cracks.
If a crack reappears after repair, it may be due to underlying movement in the concrete slab or changes in the soil beneath. For these cases, consider using a more flexible crack filler like polyurethane. If the problem persists, it may be worth consulting a professional to assess any structural issues.
Repairing concrete cracks doesn’t have to be difficult. With the right tools, materials, and a little patience, you can restore your driveway, garage floor, sidewalk, or any concrete surface back to its best condition. Addressing cracks early prevents them from growing larger and helps maintain the strength and appearance of your concrete for years to come. By following the steps we’ve outlined, you’ll be able to tackle small cracks, hairline cracks, and even more challenging repairs with ease.
However, if you find that the cracks are too extensive or you're unsure about the repair process, don’t hesitate to reach out for help. At Ergeon, our team of experts is ready to assist with your concrete crack repair needs. Whether you have questions or want a professional touch, we’re here to ensure your concrete surfaces are safe, smooth, and strong. Contact our team today for expert advice and service that you can trust!
Concrete & Pavement Guides
Concrete & Pavement Guides
Concrete & Pavement Guides
