What Is Concrete Delamination And How Does It Occur?
The following article has been written to explain a type of concrete damage known as concrete delamination and what might cause this type of concrete damage to occur. If you feel your concrete installation may be suffering from the type of damage know as concrete delamination we recommend retaining the services of a qualified concrete expert witness to perform a forensic investigation to determine the type and cause of the concrete damage at hand.
The simple definition for the word delamination is the act of splitting or separating a laminate or solid into layers. Another way to explain delamination would be the separation along a plane parallel to a surface, as in the separation of a coating from a substrate or the layers of a coating from each other. In the case of a concrete slab, a horizontal splitting, cracking, or separation within a slab for the most part parallel to, and/or generally near, the upper surface. When dealing with concrete delamination the cement used to bond the aggregate together to create the concrete has delaminated or separated causing damage to the concrete. This type of concrete damage many times will represent structural concrete damage as well as possible cosmetic concrete damage.
Concrete delamination is found most frequently in bridge decks and caused by the corrosion of reinforcing steel or freezing and thawing. It is similar to spalling, scaling, sand boils or peeling although the damage caused by concrete delamination tends to affect larger areas.
Concrete delamination investigation should be conducted by a qualified concrete and cement expert witness and in some cases may require only non-destructive tests, such as tapping or chain dragging. However, destructive testing to determine the extent of the concrete damage as well as repair recommendations for the concrete delamination may be required.
Photo on the left is an example of concrete spalling which is a type of delamination
Concrete damage known as concrete delamination occurs when the top surface of the concrete is densified or sets up prematurely or before the water in the concrete and air have a chance to reach the surface. This layer is usually thin but it will not allow the air and water from the concrete to pass through to the surface. The dense surface of the concrete blocks the upward motion of water which results from the settling of solids within the concrete mixture. As the water meets the densified thin layer, it pools laterally separating the surface from the body of concrete thereby causing damage to the concrete known as concrete delamination.
The dense top layer can form when the surface of the concrete is troweled or finished too soon.
The problem sometimes occurs when the environmental factors rapidly dry the surface of the concrete thereby not allowing the concrete to cure properly. This can include: wind, sun, low humidity, or drying the surface with heaters. This creates conditions making it appear that the surface is ready for finishing while the underlying concrete is still plastic and is bleeding air and water. Vapor barriers beneath the concrete force the water to rise increasing the potential for delamination. If you feel your concrete installation is experiencing concrete delamination or any other type of concrete damage please contact us and we will schedule a forensic investigation of the concrete damage by a qualified Concrete Expert Witness.
BFI Staff Writer