What Makes Concrete Crack?


Concrete is one of the most durable, high-strength, and crack-resistant products that last for a long time. Cracks in concrete do not happen by accident. By premature drying of concrete, two common types of cracks can be seen; crazing cracks and surface cracks. Crazing cracks are not a structural concern but there is a need to repair surface cracks and then your concrete will be as durable as it was before.

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Used with permission of Blackband Design

There are several reasons behind the cracks in the concrete. For example, if the ground on which the concrete has to be poured is improperly compacted then cracks will appear on the surface.

There are other reasons too for the cracks in the concrete, Here is a list of a few of them:

Excess Water in the Mix

The main motive behind adding water to a mixture is to make the concrete easier to install. However, if you add excess water to the mixture, it will greatly reduce the concrete’s strength. The evaporation of excess mixing water will cause shrinkage and then you will notice the cracks in your slab.

Fast Drying of Concrete

This is another common reason for cracks in the concrete. When concrete is installed, if it hardens and dries too fast then it will increase the possibility of cracking in the slab.

Improper Pouring of Concrete

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If you don’t install the mixture of concrete properly on the location, it will also cause a crack. For example, if the mixture is ready and you delay the installation of the mixture on the site then it will have some cracks on the surface.

Lack of Control Joints in Concrete Slab

In a concrete slab, there are control joints that help concrete to crack where you want it to. These joints should have the depth of the slab and its thickness should not be more than 2-3 times the thickness of the concrete in inches.

Foundations Poured in the Winter

You will see the slab will develop many more cracks if the concrete is poured or left unheated during cold months.

Method of Preventing Cracking of Concrete

Here is list of methods to prevent concrete from cracking:

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●     Erecting Temporary Windbreaks

As the rate of evaporation of water from the concrete is affected by the higher wind velocities, therefore, erect temporary windbreaks are used to reduce the wind velocity.

●     Providing Sunshades

You can control the surface temperature of the slab by providing sunshades. It will reduce the chances of cracks.

●     Proper Placement Timing

For better control over concrete temperature, you should schedule a concrete placement at the right timing. For example, in hot weather conditions, you should pour concrete in the early morning or early evening. If you place concrete in the afternoon, it will cause cracks due to loss of water. Therefore, it is better to plan the process before installing concrete to avoid cracks.


There are different cracks in the concrete due to different reasons. Some cracks depend on the temperature while others depend on how you install them. You can avoid these cracks by taking the above methods as a precaution. Thanks to concreteformworksydney.com for consulting on this post.


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