Many of us assuming that dampness cause efflorescence over the walls, Is that right? How to avoid these issues in a newly constructed walls? Comment your ideas
As usual, the best remedies of issues go to root causes. with efflorescence there has to be the presence of soluble salts in and a moisture source or migration path.
Moisture intrusion can be internal or external is wicking for a remote source, usually the foundation in contact with moist soil, or rain or similar source penetrating externally. There is also a thermal break source that promote condensation. As long as there is a source that puts the salts into solution - you have a problem.
Even if you can isolate the materials from the moisture sources, the moisture reservoir already in the material will continue allow solution and transport of the salts to the surface. Removing the salts themselves is a more problematic issues.
Some have had a measure of success in the application of absorbent poultices externally that carry the salts that increase surface evaporation and absorb the dissolved salts allowing their remove. It is a repetitive process of absorption and retreating until the salt concentration diminish to an "acceptable" level. Poultice treatment may take a bit of time over several evaporation seasons but it all for naught if the moisture ingress is not addressed as well.
Efflorescence on the masonry unit faces vs efflorescence at the lime based joint need to be distinguished. Good lime mortar is a somewhat protective mechanism in that for physio-chemical reasons the joints are acting something like a poultice drawing salts form the units. The good thing is the lime will probably unravel from the exposed joint face but can be replaced &rejuvenated by pointing - with lime mortar - NOT Portland cement (OPC) mortar .
Use a dam proof course on foundation wall, a dam proof membrane under foundation slab to stop the capillary effect of water. Moreover, add a chemical to reduce the permeability of motar use for external plastering, and use a moisture proof painting on the external walls.
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