Written By :Pitch N Hire

Tue Mar 14 2023

5 min read

What Is Spalling? Everything You Need To Know About Its Meaning, Causes and Repair

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Many a time you must have witnessed that the surface of the walls or the floor starts breaking. This happens because of multiple reasons and this breakdown is known as spalling. Spalling meaning can be understood as the breaking of stones, rocks, or ore into tiny pieces. Spalling occurs because of moisture in the concrete. It compels the surface to pop out or peel. Spalling means to flake out and so it is known as flaking. It causes the crumbling and destruction of the structure. If you ever come across a question about what is spalling? you can simply say that it is breaking off the concrete surface because of moisture and water entering into it. It exposes the underneath surface making it patchy and pitted. It is important to understand the spalling meaning and its different kinds so that you can spot it and fix it. 

Spalling is of different types. It is divided into three categories. They are aggregate, corner, and explosive spalling. Aggregate spalling does not affect structural performance. It only causes superficial damage. It mainly occurs because of aggregate failure near the surface. It starts by flying off of the small pieces from the surface. Then, later, corner flaking takes place. Large pieces start falling off the concrete owing to the development of tensile cracks in the edges and corners. At last, explosive flaking comes. It is dangerous for structural stability. It encompasses the ejection of concrete pieces from the hot surface. 

Causes of Spalling 

Spalling can be caused because of many reasons such as entering water into the brick or salt etc. It can be caused because corrosion products such as rusted steel occupy more volume than normal products. It can also be caused due to fire exposure. The free water changes to stem in concrete and create internal pressure because of fire exposure. Spalling can also occur due to the alkali-silica reaction’s vast effect. It can also occur if low-quality concrete is used to cover the reinforcing steel or because of improper construction of joints.

Once you understand what is spalling and its causes, you will be able to prevent it from taking place or repair it properly. It can be prevented by using an adequate amount of water in the mixture of concrete or by stopping the entry of water into the concrete. You can stop the water from entering it by applying a water sealant to the finished surface. 

How to Repair Spalling?

Repairing spalling once found is very important or else it will destroy the structure. Since you know the spalling meaning is to break down so breaking happens because of various factors. These factors need to be evaluated to repair the damage. Its repair depends on the degree of damage, the location of the structure, and its types. 

Clean the Area

The first step in repair is to clean the area so that bond breaker elements can be eliminated from any dirt. A pressure washer is required to clean the surface properly if dirt and heavy stains get built up. Cleaning the spalled area will help in repairing it in a better way. 

Remove Broken Concrete 

The broken and loose concrete should be removed with the help of a hammer and chisel from the concrete area. For proper preparation of the surface, shot blasting and grinding are required. For a successful repair of the concrete, it is advisable to remove the concrete of about 3.81 cm. It is very important to check for any sort of possible deterioration and this can be done by tapping the surrounding area strongly with the hammer.

If you hear any hollow sound, it means there is deterioration and that needs to be eliminated so that the need for repairing the concrete does not arise in the future. While cutting concrete parts, it is recommended to cut them in a rectangular shape. This gives better results as it helps the concrete to get contained within a specified area. Lastly, remove all the dust and debris.

Clean and Apply

The next step is to clean the dirt or rebar. It can be done using a wire brush. To eliminate corrosion, it is important to clean the steel bars that are corroded. Once the steel bars are cleaned, apply a protective coating. This helps in avoiding rusting. Once the cleaning part is done, start preparing for making repair material. Make the mixture of repair material. Numerous products are used to make the mixture depending on the severity and size of the damage. For instance, if the depth of the breakdown of the surface is less than 1/3 of the thickness of the concrete, the concrete can obtain a surface repair.

If the damage is more than 1/3 of the depth of the concrete, you will be required to install a steel bar. With the installation of steel bars, depth restoration is also needed. Roughen the affected surface and improve the bonding by applying an adhesion agent. After that, use a suitable mixture to patch the area. Ambient temperature should be considered during patching. 

Finishing, Curing, and Coating

Scrap the excess product with the help of a margin towel and in last, apply the finishing touch. The material should be cured adequately so that it can gain the needed strength. Once everything is done, apply a coat on the surface that is repaired. Apply a waterproof membrane or paint after the material is properly set.


The breaking off in fragments is known as spalling. It causes fractures in the surface. It can occur because of exposure to rebar, humidity, and water. These factors contribute to rusting of the rebar. Due to the change in weather too, spalling can occur. It must be taken care of because it damages the structure. Therefore, it should be managed carefully. Right techniques should be applied during the pouring stage to avoid spalling. It is very important to repair it because it may start with flying off small pieces but it can get changed into a serious issue and can be dangerous. Therefore, you must understand what is spalling, its causes, prevention, and its repairing techniques so that you can address the issue.

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