What is Spalling?

Malcolm Tatum

Also known simply as spall, spalling is a term used to describe the process that occurs when flakes are separated from some type of larger body of material. The separation can be caused by many different factors, including the natural process of weathering, corrosion, continual friction, or a direct impact with another object. Many materials used in machinery are subject to some degree of spalling, as well as many types of building material.

Spalling concrete shows pits and cracks.
Spalling concrete shows pits and cracks.

One of the more common types of this sort of activity is known as mechanical spalling. Often, friction and direct impact with other components in a piece of machinery results in the creation of small flecks of metal. One excellent example of a mechanical spall is the friction that a ball bearing is subjected to when a machine is in active use. The constant friction and impact with other bearings help to create the small flecks, gradually wearing down the bearings until they must be replaced.

In terms of spalling activity that is related to building materials, concrete and brick spalling are two of the most common examples. With both materials, exposure to changing temperatures, rain, snow, sleet and other weather conditions gradually wears on the surface of the construction, producing flakes in the process. Both brick and concrete spalling take place in just about any type of climate, although the rate of flaking is accelerated in areas where weather conditions are particularly harsh for most of the calendar year.

With some forms of spall activity, it is possible to repair the damage. This is particularly true with concrete. The process of concrete spalling repair usually involves the addition of a new fa├žade to the concrete, effectively replacing what was worn away over time. As similar approach to repairing spalled concrete can be used to repair bricks that have been worn down by the flaking action.

At other times, replacement is the only option when spalling has rendered the object unsuitable for continued use. Ball bearings are replaced from time to time, since there is no reliable method to resurface the bearings and restore the quality that a newly minted bearing possesses. Metal panels that have deteriorated due to flaking may also be unsalvageable, and require replacement rather than refurbishing. Generally, people who are charged with the responsibility of maintaining machinery or the exterior of buildings will know when repair can be effective, and when replacement is necessary.

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Discussion Comments


@Starjo - You need to cover the whole area that has spalled in a polymer-modified overlay of a color that matches the concrete of your driveway. After the overlay has cured, then you need to put a waterproofing sealer on it to guard against future spalling.


How can I fix the damage caused by spalling in my concrete driveway? It has flaked off quite a bit, and I know it is too late to simply take preventive measures.


Using a sealer for concrete can help prevent spalling. Penetrating concrete sealers react with the concrete chemically and provide protection from moisture and the chemicals used for deicing sidewalks. Film-forming concrete sealers, often used in decorative concrete, form a shiny film on its surface to improve its appearance as well as promote its longevity.

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