The Most Common Causes of Concrete Cracking

The Most Common Causes of Concrete Cracking

The cross section of concrete is determined by the load it is supposed to support. It is also determined from the building codes of the city you’re building it in. The design includes the strength of the concrete, the sizing, number, placement of reinforcement bards, and overall cross section dimensions. When one of these things is calculated wrongly, there may develop some damage down the line. This is the reason why you need to calculate and estimate the load against the concrete to avoid it being damaged. In this article, we will take a look at the most common causes of concrete cracking.


This is the most common cause of concrete cracking. Coming from the word itself, it means that the concrete strength is not enough to support the load its under. There are many things that can contribute to the actual strength capacity of the concrete but the most common one is underestimating the load it will need to support. If the concrete is overloaded, it can lead to a catastrophic failure but since concrete is very strong, the margin for error is not that big. Overloading mostly causes many forms of cracking and flexure under extreme load. Once you see any form of deep cracking, you need to consider professional help to quickly gauge the damage of the concrete.


Corrosion of the reinforcing steel can lead to major structural damage. Under normal conditions, the pH level of concrete is a high 12.5 which allows a layer of ferric oxide to form around the reinforcement preventing rust formation. The 2 major causes of corrosion in reinforced steel are carbonation and chloride penetration. Chloride penetration reduces the pH level and this will make the moisture penetrate the concrete thus leading to rust formation. Carbonation occurs when moisture penetrates the concrete, reducing its pH level and preventing the formation of ferric oxide which should protect the steel bars. Both of these causes affect the pH level and will end similarly, in rust formation.

Freeze/Thaw Cycle

Freezing and thawing cycles can have a huge effect on the concrete strength over time. Unless a protecting coating is put on the concrete, moisture will penetrate into the concrete every freeze and thaw cycle. Once there is enough moisture inside the concrete, it will freeze and expand. This expansion will damage the concrete and it can lead to cracking. Overtime, the cracks will grow and more moisture will seep into the concrete resulting in more expansion during the freezing. Once the concrete has enough expansion, it may collapse.

Poor Workmanship

Poor concrete workmanship also contributes to the overall quality of the concrete pour. Some of the most common human errors are: wrong aggregates, improper location of rebar, over watering of concrete, finishing too early, and more. Each one of these things can spell disaster to the quality of the concrete.

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