Traditional hot mixed lime mortars for conservation and repair

Abstract

Earth-lime and hot mixed lime mortars were the almost ubiquitous materials of traditional construction over many thousands of years but have been sorely neglected, if not ignored, by a building conservation community philosophically wedded to the principle of like-for-like and compatible repair in favour of materials with minimal historic precedent for the purposes to which they have been put. This situation has begun to change over recent years based upon growing craft experience using these mortars once more, as well as mounting evidence of the damaging potential of modern natural hydraulic limes (NHL). Historic England, Historic Scotland and CADW are reiterating the demand for like-for-like repair of historic fabric and, in most cases, this will indicate the use of hot mixed air lime or feebly hydraulic hot mixes.