In the course of investigating options on this project, I came across a verbal reference to the historical practice of slaking lime with seawater.  Claim was made that this resulted in harder, stronger and more durable lime mortar.

Seems counter-intuitive in some ways, since it would result in the introduction of chlorides into the mortar.  And we all know what soluble salts crystallising and efflorescing can do to soft lime mortar.

But perhaps the chlorides acted as a setting agent or in some other way ...

I will post this to limeonlime tomorrow as well, but maybe somebody around BP has some thoughts on this.

Cheers

david