Why is the risk of efflorescence formation in cement-based materials high in coastal areas?

Efflorescence is layer of salts left behind by an evaporating sol’n of salts on masonry surfaces. It is quite usual on plastered walls, ceilings, concrete, cement plastering, and painted walls.

Why and how does it occur? It occurs when the dissolved salts in cement, sand, and water in constructions are brought to the surface through leaching. In the second stage, the water evaporates to the atmosphere leaving powdery crystalline salts on the surface.

These salts could be present in cement due to breakdown and aging.
The sand used is of inferior quality containing salts. Though river sands are used in construction, excessive quarrying could lead to poorer quality. Instead of using sand from river or lake beds, adulteration with seashore sand could be the cause.
Water used for curing is impure with dissolved salts in it. Saline water with dissolved salts could turn out to be the culprit.

At the initial stages, the formation of a salt layer on the surface could go unnoticed. However repetitive cycles of evaporation and leaching steadily build-up the salt and the seriousness of the problem is visual. In some cases, growth in fungi could be noticed accompanied by efflorescence leading to unhygienic spaces.

Let us turn our attention to the question of the acceleration of corrosion near the seashores. Galvanic corrosion is the type of corrosion noticed near seashores. Salt in the form of aerosols reaches places located 30 KM inshore.

Salt, water, and the wind are the players that accelerate the corrosion process. Near the seashores, all these prime ingredients are readily available.