What Causes Concrete to Flake and Chip?

Learn about common causes of concrete flaking & chipping such as improper preparation of reinforcing steel, incompatible supporting metals & more. Find out how to prevent further corrosion & structural problems.

What Causes Concrete to Flake and Chip?

Concrete flaking and chipping can be caused by a variety of construction defects, such as improper preparation of reinforcing steel, incompatible supporting metals, metal bars placed too close to the surface, stress fractures due to excessive weight, insufficient concrete cover or poorly poured concrete. Carbonation is another natural process that can lead to concrete flaking. When water seeps into the concrete, it causes corrosion of the embedded elements, such as steel reinforcing bars, resulting in bulges and cracks on the surface. Poor quality steel can also contribute to chipping.

Delamination and flaking of a concrete member are not only hazardous due to potential impacts from falling chips, but they also reduce the cross-sectional area of the member and its load-bearing ability. To prevent further corrosion and structural problems, it is important to treat any existing chipping as soon as possible. For new concrete, a penetrating waterproofing sealant should be applied 28 days after it is laid and every few years thereafter. De-icing chemicals should be avoided as they can worsen existing stress in the concrete.

When it comes to peeling concrete, special attention should be paid to corners and edges of exposed concrete. If chipping and corrosion are not monitored or controlled, this can lead to failure of concrete elements. An engineer must design and evaluate the construction of a particular element to ensure that quality control methods have been carried out. The concrete cover is the thickness of the concrete between the outer edge of the member and the steel bar, which covers or protects the steel from external elements. Many state transportation departments recommend applying a waterproofing sealant to extend the life of concrete exposed to water, de-icing salts and other destructive materials.

When concrete is placed, it is essential that its steel reinforcement is properly positioned within that concrete member.