From time to time we get several house repairs needed to be taken of. Some are easy but others are urgent as they may pose a threat to the health and safety of the family. It is uncommon though for a concreter company and builders to receive calls from customers asking why their concrete is flaking and pitted and hoe the problem can be solve, some even requests for a concrete spalling repair.

With the recent abrupt changes of weather and seasons, many are in need of concrete spalling repair. But how do we know if concrete is spalled and in need of repair? How does this happen? What to do to prevent it? Keep reading and we will tell you all about it!


The spalling of concrete (also known as scaling) is a common phenomenon and problem where a few parts so of concrete break itself or peels and chips away from the structure exposing the reinforcement which is a result of a weak surface that is susceptible to damage. Spalling is caused by certain chemical reactions inside the concrete which lead to the formation of foreign products which are of high volume. These new products due to lack of space inside the concrete will increase the internal pressure.

Cracks will certainly be visible and are formed to release this pressure outside. These cracks in turn will pave way for the atmosphere to further react with the internal environment of the concrete and potentially increasing the danger failure. Concrete will begin to fall off as the cracks begins to worsen. It can be understood that this problem is mainly caused by the formation of new products.

Spalling is a very serious structural damage because the structure it is situated in are areas commonly accessed by the workers and the public and general thus exposing them to falling debris which are hazardous. If they are left unchecked, structural problems tend to accelerate and spread and becomes more unstable. It occurs mainly for one reason but sometimes a mix of these reasons. Salt, especially sodium chloride that is used on frozen roads, can result in rusting or oxidation of reinforcing steel. However, spalling typically occurs more often due to the curing process or the many ways the concrete are hardened.

These are the new products that are being formed which causes additional problems under the following conditions:

  • Corrosion
  • Alkali aggregate reaction
  • Chemical attack
  • Sulphate attack
  • Pollution
  • Freeze-thaw cycles
  • De-icing salts
  • Poor finishing techniques
  • Improper curing
  • A bad concrete mix
  • Exposure to humidity and water


Damaged Wall

Water is major contributor to spalling. Rainwater that comes from other external sources can make its way into the passageways of concrete. Once temperature drops, water begins to freeze inside the concrete. Then ice and snow forms and it expands tremendously. The expansion can cause the concrete to break that will result a crack on the surface. As the cycle continues, the outer surface will also continue to undergo spalling, causing withering. This condition is called freeze-thaw weathering.

Cracked Wall

A natural processed called carbonation is also a major contributor to spalling. Other elements, especially reinforcement bars embedded in the concrete to corrode are caused by water that is immediately seeped into the concrete. Hence, it creates bulges and cracks in the concrete surface. Steel reinforcement bars are often used in concrete to provide durability. Also, steel that is poor quality can cause spalling.


It causes spalling because of poor installation. It refers to an inappropriate combination of ingredients while pouting the concrete during the construction. When a structure is being subjected to high pressure through overloading, then it can also be a major contributor.


When a fire incident occurs, cold water is poured on heated concrete surfaces which can break the materials like sand and gravel that will cause the concrete to crumble which in the end causes spalling also.

High Temperatures

It is to be expected that spalling will occur during hot days due to high temperature. The surface gets hotter compared to underneath when concrete is exposed high temperatures suddenly or over time. these condition leads to differential thermal expansion, which can result to stress between the surface areas and because of this, large masses of concrete start to detach and develop cracks.

Rock Salts and De-icing

Water that contains dissolved salts will penetrate the concrete. Crystallization will happen inside during water evaporation. The salt crystals will expand in volume, resulting from creating stress on the concrete which in result wears away the surface.

Remember: When you notice things like what is mentioned above, it is better to call spell concretor so they can assess the situation and will eventually decide whether a concrete spalling repair is needed or not.


Important note: if you are unsure or unknowledgeable about spalled concrete or concrete structures in general, you should contact a structural engineer or a concrete spalling repair specialist to assess the situation before you can cause more damage.

  • Concrete usually can receive a surface repair if the spalling damage is shallower than 1/3 of the concretes thickness. Steel bars may be need to be installed and a full depth restoration may be required if the damage is greater than 1/3 of the depth.
  • Corroded rebar, due to exposure, must be cleaned at the beginning of the restoration process. A wire brush can be used to thoroughly cleaned so that all corrosion is removed, the rebar should receive a protective coating of rust inhibitor to minimize future corrosion.
  • A cementitious overlay can quickly fix damages on driveways, walkways, and other horizontal surfaces. A waterproofing membrane should be applied to prevent spalling from recurring should be done after the overlay has completely set.
  • For localized or random damage, patching may be a repair option. Patches should extend at least four inches beyond the spalled areas. The surface can be saw-cut in the patch area to help contain and secure the patch for best result.
  • Surfaces to be patches should be free of all debris and fine particles and should be completely dry before patching material is applied. To provide tooth for better bonding, it is best if the old concrete surface is rough.
  • The air temperature must be over 40 F for patching or other restoration work to ensure proper bonding and curing of the repair material.
  • Repair materials should have an expansion coefficient similar to that of the original concrete.
  • Any joints that are repaired must allow for the expansion of the concrete slab.


Concreter Sydney is home to the best concrete contractors Sydney. From simple concrete driveways, finishing to concrete construction and concrete spalling repair, we can make it happen for you. If you would like to know more, explore our official website or contact us so we can answer your questions directly.