Lime and earth vernicular mortar data

[I_Rae]

Hi,

I'm working on a building with solid stone walls of 600mm deep and the mortar used is lime and earth which would typically be 10% pure lime and the balance as earth subsoil(gravel, silt and clay composite for the location)

I tried building the existing wall model(WUFI 7.1) by using the closest materials in the portfolio as a starting point, using 80% Sandstone + 20% historic lime mortar in a build up as follows:

[128mm S/St][30mm Lime][128mm S/St][30mm Lime][128mm S/St][30mm Lime][128mm S/St]

The mortar starts with a water content in the first year(20kg/M³), reduce on the 2nd year( and then on 3rd year and going forward it continues to accumulate water content, not by much but keeps accumulating without normalising, even after 8 years!

This seems weird right? The water content accumulation isn't high and maybe I have set my initial water content set too low for the locational weather. So Ill try and set it higher to see if it decreases but is there something wrong in my composition of the wall please?

[Christian Bludau]

Hi,
the moisture may initially dry out in the first few years and then increase - that can happen. In the first few years, the initial moisture is distributed and adapting to the boundary conditions; areas on the outside may dry out more quickly, while the moisture from inside the building takes longer to reach the boundary. Later, when the gradient has adjusted accordingly, the construction slowly absorbs moisture again.
Christian