During brick installation on a commercial building facade, the mason notices efflorescence appearing on completed sections. What is the most likely cause?
Correct Answer
B) Moisture migration through the wall carrying soluble salts
Efflorescence is caused by water-soluble salts in masonry materials that migrate to the surface through moisture movement and crystallize when the water evaporates, leaving white deposits.
Why This Is the Correct Answer
Efflorescence occurs when water moves through masonry materials, dissolving soluble salts present in bricks, mortar, or concrete. As this moisture migrates to the surface and evaporates, it leaves behind white crystalline salt deposits. This moisture migration can happen through capillary action, hydrostatic pressure, or vapor transmission. The salts are naturally present in masonry materials and become problematic only when water provides a transport mechanism to carry them to the visible surface.
Why the Other Options Are Wrong
Option A: Excessive water in the mortar mix
While excessive water in mortar can contribute to moisture problems, it's not the direct cause of efflorescence. The white deposits are specifically salt crystals that must migrate from within the masonry materials to the surface. Wet mortar alone doesn't create the salt deposits characteristic of efflorescence.
Option C: Inadequate curing time between courses
Inadequate curing time affects mortar strength and bond but doesn't directly cause efflorescence. The salt deposits form from existing soluble salts in materials, not from timing issues. Proper curing actually helps reduce moisture content, potentially minimizing efflorescence risk.
Option D: Using the wrong type of mortar joint finish
The type of mortar joint finish affects appearance and weather resistance but doesn't cause efflorescence. The white salt deposits originate from within the masonry materials and migrate outward, regardless of the joint finishing technique used on the surface.
Memory Technique
Remember 'SALT TRAVELS': Soluble salts Always Leave Traces when water Transports, Revealing Accumulated Visible Evidence on the Surface.
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