Complete Guide On How To Repair Cracks In Concrete

The Best Way to Repair Concrete Cracks

Maybe it’s time you fixed that crack in the sidewalk or patched up that hole in your garage. Whatever the case may be, this guide will help you do it yourself, without hiring a professional. Here is a step-by-step to patching holes and fixing cracks in your concrete.

So, how can you repair cracks in concrete? Most people think that you need special contractors when it comes to repairing the concrete around your home, but that’s simply not true. You yourself can use regular cement mix and a few other things you usually have at home, like sand and gravel. Concrete is strong yet porous; there are thousands of tiny holes deep inside concrete where water can reach the steel reinforcing bars (rebar).

Concrete Epoxy Repair
Concrete Epoxy Repair

Sometimes you might need to do a little patching or filling, but often it’s as easy as adding more concrete mix. Concrete patches help to reinforce a weak area in the concrete or cover up an unsightly crack. Keep reading to learn more about how to repair concrete cracks around your home!

Choosing a Concrete Patching Material

Before you can choose a patching material, you must know what kind of crack or hole you are dealing with.

Different Types Of Concrete Cracks

  • Small Cracks or Hairline Fractures: Mortar is best for small cracks and hairline fractures up to 1/4 inch (6 mm). In those cases, you can install epoxy-coated mesh tape over the crack to reinforce it.
  • Medium Cracks: If you have a slightly larger crack that’s up to 3/8 inch (10 mm) wide, use a polymer-modified dry-pack mortar patch. It can be troweled on the same day and is more flexible than regular mortar patching material.
  • Large Holes or Cracks: Large holes or cracks should be patched with a polymer-modified dry pack mortar. This type of patch is more flexible than regular mortar and can help to reduce the possibility of further damage.

 

Mortar is generally used for small holes and cracks that aren’t too deep or wide. It’s a mixture of cement, sand, and water which hardens as it dries. Bonding agents are also added to help the patch stick to the concrete.

Some cracks may be too deep, wide, or structurally unsound to patch with mortar. In that case, you will have to use a different form of material such as plastic foam, epoxy putty, or rubberized asphalt filler.

Patching Concrete With Mortar

Although most cracks and holes up to 3/8 inch (10 mm) can be fixed with a regular-mixed, ready-mix mortar, thicker patches may require a more plastic variety known as a dry pack.

It contains separate materials of cement powder, fine aggregate, and additives such as acrylic resin or rubber particles.

Tools:

  • Trowel
  • Bucket for water
  • Concrete float

Materials:

  • Concrete sand (1/3 of the total sand)
  • Portland cement (1/3 of the total sand.
  • Mason’s sand or fine sand (the last 1/3 of the sand)

Instructions:

  • Make sure the surface is clean and dry.
  • Prepare the patching mixture. Mix the dry ingredients first then slowly add water until you get a smooth, creamy consistency.
  • Apply the material to the hole with your trowel. Pack it in firmly, but don’t leave any air bubbles because they can cause weak spots in the final coating.
  • Use the trowel to smooth out the surface of the patch so it matches the rest of your concrete.
  • Feather out the edges with a wet finger to get rid of any excess material that could cause chipping or cracking later on down the road.
  • Once you’ve finished smoothing, let it dry for at least 30 minutes, then use the concrete float to re-smooth the patch.
  • Let it dry for a solid 24 hours before applying any heavy weight on top of it.

Patching Concrete With Rubberized Asphalt Filler

Rubberized asphalt filler, or “cold mix” for short, is a material that repairs cracks in the concrete without having to break up the existing surface. It’s very inexpensive and can be used indoors or outdoors.

Materials:

  • Rubberized asphalt filler
  • Trowel
  • Bucket of water

Instructions:

  • Clean the area around the hole by brushing it clean with a broom.
  • Scrub the area around the crack with soap and water to remove oils and dirt. Rinse well and let dry.
  • If you’re using pre-mixed mortar, follow the manufacturer’s instructions for mixing ratio; usually, it is 1:1 (cement to sand). If you’re using powder/liquid mortar, mix 1 part powder with 2 parts water.
  • Apply mortar to the hole using a margin trowel. It should be about 3/8″ thick all around and slightly higher than the area surrounding it (about 1/2″).
  • Allow the patching material to set according to the manufacturer’s instructions for 4-6 hours, then smooth out any roughness with a steel trowel.
  • After the patch is completely dry (usually 24-48 hours), apply an epoxy-based sealer to protect it from moisture and possible future cracking. You can also paint the area if desired.
  • To reduce further damage, you may want to apply a concrete overlay, which is a thin layer of concrete applied over the crack. To do this, you will need to cut away loose or excess material with a cold chisel and hammer before finishing with the patching material.

Patching Concrete With Plastic Foam

Plastic foam is one of the more expensive options for filling in cracks and holes, but it’s also quite effective. If you need a quick patch that will hold up to high-traffic areas, plastic foam can do the job.

Tools:

  • Plastic foam comes in 2 parts – A liquid component and a solid component.
  • Plastic mixer
  • Mixing sticks or spoons

 

Materials:

  • Plastic foam
  • Trowel
  • Bucket of water

Instructions:

  • The liquid is thin so it will run into the crack and allow you to fill it up quickly.
  • Make sure the area is free from debris. Then use a broom to sweep away loose dust and dirt.
  • Mix the 2 components of the product thoroughly, then let it sit for 10 minutes.
  • Pack it into place with your trowel or putty knife, filling all voids.
  • Feather out the edges with the side of your trowel or putty knife to get rid of any excess material that could cause chipping or cracking later on down the road.
  • Once you’ve finished filling, use a wet broom or sponge to smooth out the surface of the patch so it matches the rest of your concrete.
  • Let it dry for at least 24 hours before applying the weight of traffic on top of it.

Patching Concrete With Polymer-Modified Dry Pack Mortar

Polymer-modified dry pack mortar isn’t itself a filler, but it can be used to fill in cracks before applying an overlay. This is the best option if you’re looking for a very inexpensive method that has some strength behind it.

Tools:

  • Broom to sweep up any loose debris
  • Bucket of water

Materials:

  • Fiber mesh dry pack mortar patching material
  • Polymer-based dry pack mortar patching material (premixed or powder/liquid mix)

Instructions:

  • Clean the area around the hole by brushing it clean with a broom.
  • Scrub the area around the crack with soap and water to remove oils and dirt. Rinse well and let dry.
  • If you’re using premixed polymer-based dry pack mortar, follow the manufacturer’s instructions for mixing ratio; usually, it is 1:1 (cement to sand). If you’re using powder/liquid polymer-based dry pack mortar, mix 1 part powder with 2 parts water.
  • Apply the mortar to the hole using a margin trowel. It should be about 3/8″ thick all around and slightly higher than the area surrounding it (about 1/2″).
  • Allow the patching material to set according to the manufacturer’s instructions for 4-6 hours, then smooth out any roughness with a steel trowel.
  • After the patch is completely dry (usually 24-48 hours), apply a high-quality polymer-based sealer to protect it from moisture and possible future cracking. You can also paint the area if desired.

Examples of Pre-Mixed Mortar

Many companies sell pre-mixed dry pack mortar products so you don’t have to make your own. They are available in many different colors, strengths, and sizes.

Some of these companies include the following:

  • Ready Mix
  • Sackboy
  • Stalco
  • Instant Patch (Cement Board)

Examples of Polymer-Based Dry Pack Mortar

There are many different pre-mixed polymer-based dry pack mortars on the market. They are available in many different colors, strengths, and sizes.

Some of these companies include the following:

  • Quikrete
  • Ready Mix

Some examples of powder/liquid polymer dry pack mortar mix you can make yourself include:

  • 2 parts sand to 1 part Portland cement or masonry cement (for small repairs)
  • 1 part masonry cement to 1 part fine, mason sand (for larger repairs)
  • 2 parts Portland cement plus lime to 3 parts sand for insulation patching

In Summary

Concrete repairs can be simple but it is important to know when you need help. If you are uncomfortable with the quality of your repairs or unable to do them yourself, it is best to hire a professional. No matter what type of damage has been done to your concrete, there are ways to fix it so that you can have no problems in the future.

Matt McWilliams
experthomereport@gmail.com

Hi there! My name is Matt and I write for Expert Home Report. I enjoy writing about everything related to home improvement, home tips and DIY. In my spare time, I'm either spending time with my family, doing a DIY project or learning a new skill.