How to Repair Cracks in Concrete 

 November 15, 2020

By  Dale Keese

Concrete is very durable and a concrete installation can last for a very long time. However, most concrete installations develop gaps, cracks, crevices, and holes sooner or later. If your concrete driveway, garage floor, path, or patio is developing cracks, it is better to make the necessary repairs immediately.

Shoeprint and Cracks

If you do not know how to repair concrete, what may start off as a small problem is only likely to get bigger and more difficult and expensive to fix.

Cracks in concrete typically start to appear because of thermal movement, shrinkage, or some other causes. The danger is that these cracks can widen over time and cause water seepage, which can result in the structural integrity of your home being compromised. 

Cracks in your concrete driveway, walkway, garage, patio and foundation are not only unsightly but also can be a hazard. They can cause you to trip and fall. Another effect is that they can lower the value of your home. This is why you should know how to fix cracks in concrete so that you can repair them immediately.

Before you repair the concrete crack, it is a good idea to assess the general area and determine the cause of the crack. You need to assess if the structural foundation of your home has been compromised and if yes, you must determine the root cause, which could be:

  • Thermal expansion due to weather conditions or shock
  • Excessive loading
  • Cold weather conditions when the foundations were laid
  • Faulty conditioning or measurements on original laying
  • Exposure and damage of steel reinforcements
  • Extreme shrinkage while curing
  • Subgrade settlement
  • Fire or corrosion causing degradation
  • Tensile strength is greater than the concrete’s strength

If the concrete crack has resulted in structural damage, then you will need to use a flexible material and technique to resolve the problem. In the case that the concrete crack is a non-structural problem, i.e., a decorative or aesthetic problem, even then, the issue must be addressed. 

You still have to know how to fix cracks in concrete as soon as possible before the cracking spreads or worsens. Hairline or less critical concrete cracks could be due to:

  • Infiltration of tree roots
  • Shifting foundations
  • Water seepage
  • Hydrostatic pressure
  • Creep damage
  • Oxygen, carbon dioxide or chloride entering the concrete

Any cracks in the concrete must be fixed to achieve any one of the following:

  • To increase the strength of the concrete that has cracked
  • To improve the durability of the structure
  • To prevent any liquid from penetrating the concrete
  • To improve functional performance
  • To ensure public safety
  • To prevent any corrosion in the future
  • To make your concrete look good

You must first eliminate the cause of the problem before fixing a crack in the concrete. Preventing further damage to the concrete is essential to the success of the repair job you undertake. Also, how to repair cracked concrete depends upon the size of the crack.

Repairing concrete cracks may seem like an overwhelming task. However, these days, there are a lot of quick DIY methods, which enable you to do the repairs yourself.

How to Repair Cracked Concrete

Pink Building with White Shutters

Choosing a Concrete Repair Product

You cannot repair concrete surfaces using concrete alone. Instead, you need to make use of a concrete repair mix, which is available readily online or at home improvement stores. There are different types of concrete repair mixes available such as latex patching material, epoxy compounds, and mortar mixes.

When doing DIY concrete crack repairs, keep in mind that latex  patching materials and epoxy compounds are suitable for concrete cracks which are 1/8-inch wide or narrower. Mortar mixes work best to fill chipped edges or large cracks.

Preparing the Cracked Area

Before you start to repair concrete cracks,  it is very important to prepare the area that needs fixing.

  1. 1
    Using a hammer and chisel, knock away any loose, cracked, or crumbling concrete and widen the base of the crack. Chip the concrete to around one inch below the surface.
  2. 2
    Then, scrub the area vigorously with a wire brush. This will loosen any dislodged particles in the crack.
  3. 3
    Rinse the area with clean water using a garden hose or a power washer.
  4. 4
    Remove all the water and debris from inside the crack using a brush or a dry or wet vacuum. Remove all the grit and dust from the crack. If the surface of the concrete is wet, then this does not matter. However, there should be no pools of water.

This part of the job can get quite dusty. The cleanup and after care will be easier for you if you spread a tarp in the area you are working on. Most importantly, ensure that you are wearing proper eyewear, rubber gloves, and protective gear every time you do concrete crack repair.

Working in Construction

Applying the Patching Product

Steps to Repair Narrow Concrete Cracks

You can fill cracks in concrete that are narrow or small using latex or epoxy patching products. You can apply the product by using a caulking gun. Some of these products are available in bottles with applicator tips. For hairline or very small cracks, you can use a vinyl concrete patching compound to fix the crack.

You must apply this compound over the crack and then smoothen it using a trowel or putty knife. Usually, in the case of hairline cracks, applying the crack filler or caulk over the cracks is not effective. Over time, the caulk starts to peel off the concrete surface. Read on to know the steps on how to fix concrete cracks.
  1. 1
    For cracks that are 1/8-inch wide or narrower than this, you must use a latex or epoxy patching products that you should mix as per the manufacturer’s instructions.
  2. 2
    Use a putty knife or a mason’s trowel to apply the product.
  3. 3
    Force the product completely into the crack and then smoothen it. Make sure that it is in level with the surrounding concrete.
  4. 4
    Then, allow the mix to cure. Every mix has a different curing period and you must refer to the manufacturer’s instructions listed on the product you have selected.
Working with Cement

Steps to Repair Wide Concrete Cracks

In the case of larger cracks and imperfections, use a mortar mix. You can create a DIY crack repair mix, which is extremely simple. Combine one part Portland cement, three parts of masonry sand, and sufficient water. Mix them all together to form a thick paste. Now you have your own mix for repairing cracks in concrete. 

You also have the option of purchasing a readymade repair mortar mix online or from your local home improvement store.

The most important thing to do when repairing wide cracks in the concrete is undercutting the sides of the crack so that it gets an inverted “V” shape. This allows the mortar mix to get into the crack and create a mechanical bond, as well as a chemical bond between the patching material and the concrete. 

Read on to know the steps on how to repair concrete with wide cracks.

  1. 1
    Moisten the cracked concrete surface, but take care not to drench it with water.
  2. 2
    Apply the mortar mix using a putty knife or a mason’s trowel.
  3. 3
    As you apply the crack repair product, take care to remove the air pockets by pressing the applied product down very firmly. Fill the crack till the surrounding concrete surface.
  4. 4
    Smoothen the patch with the trowel so that it is level with the rest of the concrete.
  5. 5
    Brush the patching compound surface with a paintbrush if you want a textured surface.
  6. 6
    Let this cure for around two hours and then cover it with a plastic sheet so that the area remains moist. Sprinkle water daily under the plastic sheet for a few days or until the concrete surface has hardened.
  7. 7
    Paint or seal the surface of the patch and the area around it.
Woman Wearing A Hard Hat

Now that you have learned how to repair cracked concrete, there is no need to go into panic mode when you notice cracks in any concrete structure in your home.  With a few materials on hand and a bit of patience and effort, you can easily fix the crack and get the concrete looking brand new in no time at all.

About the author

Hey, I'm Dale Keese.. thanks for reading.. hopefully this article can save you some time and trouble with your sealing job. I'm also in the process of making some video walk-throughs for youtube so check back soon! thanks

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