any ideas on how to stop it, I am sure that a lot of people in this area would like to hear about them. In the first picture, the original wall was concreted for the first five feet to try and stop the fretting, but it kept on going above the concrete. The second picture shows how the small wall is virtually reduced to sand by the rising salt damp and the other two are just more examples of the destruction rising salt damp can cause.
The efflourescence (as its called) is no more foriegn to Calciferous Limestone than the processes which made the limestone somewhere between 300,000 and 3 Billion years ago. What has changed is two things. First we cleared the land, the water table rose and brought with it the salt. Well...its a factor...but if you wander over to the nearest naturally occuring limestone outcrop you will see some of the same but no where near the devestation (in a relatively short period) that you see in RnR's pics.
So the other factor is cement/concrete. Limestone will survive the salt attack, more or less, provided there is not continuous moisture with which to make the acids. The beauty of limestone is that it breathes. Moisture goes nearly as fast as it comes. But if you build limestone on damp concrete slabs (with a rising water table), or coat all over the face with hard concrete you retain the moisture and accelerate the effect of the efflourescence. Effectively you stop the limestone breathing and then you are screwed.
The solution....:Banghead...is to remove all the well meaningly applied cement render and pointing (is meaningly a word), gouge out the joints by hand (no power tools allowed:nono) and use lime based mortar (with various secret stonemasons aggregates). Point the joints up to but not more than 1" of the face of the stone so the stone can breathe and moisture will travel through the mortar as well as it will the stone.
If you look to recommendations for Portland Cement you will see that they increase the quantity of cement for proximity to the sea...in other words, to make the cement stronger. I say, go to the land of the Leprechaun, Guinness and the
Bearlager na Saor (the old language of the masons) and see 12th century castles built from Carboniferous Limestone and Lime mortar...standing on the edge of the North Sea....and then make you decisions about how to repair natural stone buildings.
Sorry for the side track, but you can imagine in a world where concrete, steel, strength etc is the engineering norm...I cop a bit of a beating on the subject. Sometimes, you need to look backwards in order to go forwards.
The simple solution to most efflourescence is to remove the moisture depending on the chemical constitutents. RnR, if somebody wants to pay me a hundred grand a year to fix your old building I'd gladly do it for the rest of my life......and not have to worry about skid steers and trucks and excavators and...and...and
