Fascinating study of dampness and salts. Love the detail. One idea I've heard is that if capillary diameters in mortar are smaller than in stone, there should be pull of moisture away from stone and into mortar. So maybe soluable salts end up accumulating within the mortar and not stone / brick, in that case. Are there experiments that shed any light on this idea? I guess if this is true then over time salt accumulation within mortar would slowly reduce breathability anyway.
Historic England might have published some studies in this regards, I have been reading about this in the past. However, based on 4+ years of intense moisture research in-house I don't think things are that simple. Everyone seems to focus these days on capillary action of mortars and neglect the vapour phase. Based on our experience most of the drying occurs through evaporation and vapour movement, rather than capillary movement. There's definitely more research needed in this area as the phenomenon is complex involving many moisture transport mechanisms.
As far as I know, evaporation dries the walls, it's the primary drying mechanism. You can read more about the salt here: www.coreconservation.co.uk/the-effect-of-ground-salts-onto-masonry/
Fascinating study of dampness and salts. Love the detail. One idea I've heard is that if capillary diameters in mortar are smaller than in stone, there should be pull of moisture away from stone and into mortar. So maybe soluable salts end up accumulating within the mortar and not stone / brick, in that case. Are there experiments that shed any light on this idea? I guess if this is true then over time salt accumulation within mortar would slowly reduce breathability anyway.
Historic England might have published some studies in this regards, I have been reading about this in the past. However, based on 4+ years of intense moisture research in-house I don't think things are that simple. Everyone seems to focus these days on capillary action of mortars and neglect the vapour phase. Based on our experience most of the drying occurs through evaporation and vapour movement, rather than capillary movement. There's definitely more research needed in this area as the phenomenon is complex involving many moisture transport mechanisms.
How does salt get into the wall if it is evaporation which wets the wall.
As far as I know, evaporation dries the walls, it's the primary drying mechanism. You can read more about the salt here: www.coreconservation.co.uk/the-effect-of-ground-salts-onto-masonry/