Case Study

Observational study

Cement repair on a house with different street levels. This is more about lime mortar specification not solving this problem.

Here are a few lime mixes that also wouldn't work if used in the same way. And a few notes about the issues with this kind of situation.

LIme putty wth sharp sand, not soured off and untempered with only sharp sand. But soured off, with fines/pozzalon and very well beaten might work. 

Too porous and not hydraulic, meaning too much water ingress and an inability to cure.

Hot lime with only sharp sand.

As above but may cure in some circumstances without pozzalon.

NHL with, guess what?, only sharp sand.

Too porous, not enough drying action and already too salt laden.

Among others, but these are the obvious candidates in my area which is predominately lime/sand or lime/subsoil with very little chalk, lime aggregates etc.

All lime mortars are capable of taking on salts, this is part of their sacrificial nature, to do this and then be replaced as it can reduce the breathability and eventually that salt can spread into the building units. It is likely the wall will have a lot of salt in it meaning this could happen very fast indeed with a very porous basic lime mortar.

You could potentially use some of them IF you solve the problem first. But pragmatically speaking this house isn't valued high enough for that to be cost effective. So an alternative solution would need to be found.

My point is that this water isn't here solely because of a lack of lime, its more complicated than that. And the benefits of lime can also be negative. Often bringing more moisture into an environment than you want, similar to trying to use a dehumidifier to fix ongoing damp. You're creating a temporary dry environment for more moisture to get into, in both circumstances. The lime also creates a faster route for the water.

Fix the problem, remove as much dirt, salt etc. THEN install lime products. And the right ones...