Efflorescence is a construction defect caused by improper vibration during concrete placement.

• A. False
• B. True
• C. Not Applicable
• D. Both

Answer: (A)

Efflorescence is a salt deposit that forms on the surface when moisture moves through concrete or masonry, dissolving soluble salts (like calcium hydroxide) from the cementitious material and then leaving crystals behind as the water evaporates. It’s driven by moisture transport and porosity, not by how the concrete was vibrated during placement. Improper vibration can cause other issues—such as honeycombing, segregation, or laitance—but it does not create the white crystalline efflorescence. In bridges, you’d look for signs of moisture sources or salt exposure that could keep bringing salts to the surface, and you’d address it by reducing moisture ingress, improving curing, using lower-alkali cements, and sealing surfaces to limit salt transport.