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Why Concrete Cracks & How to Fix Cracks in Concrete

Concrete surrounds us: sidewalks, driveways, ramps, patios, parking garages, and structures. It’s one of the strongest manmade materials that can hold extreme weight and weather nearly any storm. Though concrete is one of the toughest building and construction materials, it can crack.

If you’ve ever seen a driveway with cracks, a concrete building with cracks, or cracks in a home foundation, you’ve probably wondered why such a strong material can break. Continue reading to learn why concrete cracks and how to fix cracks in concrete.

What is Concrete?

Before we discuss why concrete cracks and how to fix cracks in concrete, let’s first discuss what concrete is to understand more about this extremely durable material. Did you know that concrete has ancient roots and has been around since 6500 BC? Its first known use was in the deserts of Jordan and Syria, used in cisterns and flooring. Since then, it’s evolved and is used for walls, foundations, floors, furniture, and even art pieces!

Often confused with cement, concrete is made from a few ingredients: aggregates like sand, crushed rock or gravel, cement, and water. The cement used to create concrete consists of natural matter like chalk, marl, or lime. Cement is used when making concrete because it binds all three ingredients—aggregates, cement, and water—together and hardens everything. When the cement mixes with water and the aggregates listed earlier, it forms concrete. Portland cement is the number one ingredient in nearly every concrete, thanks to its ability to harden into a solid.

Why Does Concrete Crack?

Some homeowners will wonder if they made a mistake when hiring a builder or polyjacking company when they notice a crack in their concrete driveways, foundations, patios, and buildings. Though it’s one of the strongest materials available for construction and building, concrete can crack.

If concrete is one of the strongest materials, why does it crack? There are several reasons why concrete may crack:

  • Wrong strength
    • Did you know that concrete comes in different strengths? It’s not a one-size-fits-all material and structures require different strengths to support a certain structure or weight. For example, portland cement has a compressive strength of 20-40 MPa (million pascals or 3,000-6,000 psi).
  • Concreted dried too fast
    • If concrete dries too fast, it might not be as strong and is prone to cracking. Moisture in the concrete should evaporate at a certain speed, and if it dries too fast it’ll be compromised.
  • Wrong control joints
    • Control joints are placed where you want cracks to be inside the concrete. Therefore, it would crack if the concrete was poured and the control joints weren’t in the right spots.
  • Issues with pouring concrete
    • Concrete needs to be poured at a temperature above freezing. If poured on frozen ground the concrete could crack. 
    • Concrete poured on the ground that isn’t compacted will crack

Concrete can crack for other reasons, but the above are the most common reasons for concrete to crack.

How to Avoid Cracks in Concrete

Cracks in concrete can be a nightmare to deal with, especially if you hired a professional company to pour concrete that resulted in a disaster repair or outcome. Luckily, most cracks in concrete can be prevented assuming the concrete is poured correctly. 

To avoid cracks in concrete you’ll first need to choose an appropriate concrete strength for the job. For example, don’t choose a weaker strength for a driveway that parks multiple vehicles. Next, use high-quality concrete for the best outcome. 

You’ll also want to place control joints in the right places to ensure cracks happen where you want them to, not the other way around. A professional concrete contractor who’s experienced in pouring concrete will know how to ensure the concrete dries properly and how to pour it to avoid cracks.

How to Fix Cracks in Concrete

Depending on how severe cracks in concrete are, they can be fixed and leveled, it might require a different concrete leveling technique. The following are some ways to fix cracks in concrete:

Apply a Concrete Crack Filler

Best for narrow concrete cracks, concrete crack fillers can be applied to smaller cracks to fill the space. They’re a relatively easy DIY, requiring just a few materials to complete the job like a caulking gun, sledgehammer, and trowel. There are a few different concrete crack fillers like a patching compound or concrete crack filler.


For filling in and lifting concrete, consider polyjacking. Polyjacking injects a polyurethane foam under a concrete slab by injecting the foam under tiny holes. This process stabilizes the soil and as a result, lifts the concrete to fix cracks and level the concrete.

Concrete cracks are unsightly, especially if they’re on a commercial building you own, your home’s foundation, uneven driveway, patio, or other concrete structure. Trust the professionals at Pro Polyjacking in Kansas City for your concrete repair. Contact the team at Pro Polyjacking for more information about how to fix cracks in your concrete!