Delamination is the subsurface separation of concrete into layers. (T/F)

• A. True
• B. False
• C. Not applicable
• D. Not sure

Answer: (A)

Delamination refers to a separation that occurs beneath the surface of concrete, running parallel to the top face, so a distinct internal layer becomes detached from the layer above or below. This makes the statement true. The surface may look fine while a puckered or weakened plane lies just below, which is why delamination can be hard to detect without inspection. It often happens because of trapped air voids, inadequate consolidation during placement, moisture movement, or stresses from temperature changes and reinforcement corrosion that push layers apart. Because the separation is subsurface, you might notice a dull or hollow sound when tapping the area, and more detailed nondestructive tests like impact-echo or radar can pinpoint the delaminated zone. If left unaddressed, the weak plane can grow, leading to cracking, spalling, or reduced structural performance. Repair typically involves removing the affected concrete and restoring the bond and load transfer, followed by measures to correct the underlying causes and prevent recurrence.