Top 8 Reasons Concrete Cracks?

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    Concrete is a popular material for construction projects, but it’s not perfect. The cracking of concrete is a common issue that contractors and homeowners face. There’s nothing worse than finding a cracked concrete slab in your patio or driveway, especially if you just had it installed. But what causes concrete to crack? Also, is there anything you can do to prevent new surface cracks in concrete slabs and floors?

    Whether you are planning a new project or dealing with existing damages, understanding the seven reasons why concrete cracks can help you prevent them in the future.

    #1 Shrinkage Cracks When Concrete Dries Too Quickly

    Cracks in concrete floors are commonly caused by expansion and contraction. Like most materials, concrete expands when it heats up and contracts when it cools down. 

    So, why does concrete crack when drying? 

    During the curing process, concrete shrinks as it dries and hardens. Stress cracks in concrete can be caused by this shrinkage, as the rigidity of the material causes it to pull apart. 

    This type of shrinkage cracking in concrete is called “plastic shrinkage cracking.” It is most common in hot weather because concrete dries faster in warm temperatures. 

    #2 Too Much Water Added To The Mix

    Plastic shrinkage cracks can also happen when too much water is added during the mixing process. Although adding more water makes installation easier, the concrete will shrink more. And as we have just learned, excessive contraction leads to more cracks. 

    #3 Expansion Cracks

    When concrete heats up, it expands. This expansion pushes against whatever is restraining it, whether that’s the ground or another concrete slab. If there’s no room for expansion, cracks will form as a result of the pressure. That’s why expansion cracks often happen in concrete slabs next to sidewalks, driveways, and other concrete surfaces.

    One way to mitigate this damage is to use expansion joints, which are gaps that allow concrete to expand without cracking.

    #4 Lack Of Control And Expansion Joints

    In this world, there are two types of concrete – concrete that has already cracked and concrete that will crack. This inevitable fate is harsh but true. The solution to mitigate the problem? Control joints and expansion joints.

    Control joints are weakened lines that are intentionally cut into the slab as it dries to control where cracks will form. By doing this, the cracking is less likely to be a problem because it will happen where you want it to happen.

    Expansion joints are gaps designed to accommodate the expansion and contraction of concrete. By providing a space for the material to move, it is possible to prevent it from cracking under the expanding pressure.

    #5 Low Strength Concrete

    Another common cause of cracking is poor-quality or low-strength concrete. 

    Concrete is available in different strengths. If the inappropriate strength is selected for the project, it can be too weak and susceptible to cracking. 

    An improper curing process can also lead to poor-quality concrete that is more likely to crack.

    #6 Weight Overloading

    Concrete is strong, but it has its limits. For example, if too much weight is placed on concrete (from things like vehicles or heavy machinery), it can crack. In addition, if the concrete is not thick enough for the load it supports, it can also lead to cracking.

    #7 Freezing Temperatures

    When concrete gets wet and then freezes, it can crack. In simple terms, here’s why:

    • Concrete is a porous material, so it can absorb water. 
    • When water freezes, it expands and increases in volume by 9%. 

    When water seeps into concrete and freezes, it expands, putting pressure on the concrete and causing it to crack.

    #8 Tree Roots

    Although trees are a beautiful addition to any property, their roots can wreak havoc on your concrete. As tree roots grow, they put pressure on the surrounding ground. This pressure can cause cracks in concrete sidewalks, driveways, and patios.

    Although chopping down the tree may seem the obvious solution, it’s not always possible or desirable. In these cases, you may need to have the tree roots removed by a professional.


    As you can see, “what causes cracks in concrete” is a complicated question with many possible answers. By being aware of the most common problems – and by working with a reputable contractor – you can help ensure that your concrete project will succeed.

    Check out our article “5 Things to Look for in a Concrete Patio Contractor” for more tips on making your dream outdoor living space a reality.

    Thanks for reading! till next time, bye. 🙂

    Looking to get rid of cracking of concrete in your outdoor living space? Affordable, professional outdoor living space construction services are just a call away with All Pro Decks. We strive for customer satisfaction and make your outdoor living space a reality. Get A Free Estimate Today!

    Justin Wylie

    Justin Wylie, owner of All Pro Decks & Patios is a Deckorators® Certified Pro Elite located in the San Antonio Hill Country area. He specializes in building decks, patios, patio covers, pergolas, concrete slabs, fireplaces and more while providing quality and service for his customers.

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