Investigation of hydraulic lime mixes used in building conservation and their effects on globigerina limestone : the investigation of water movement, porosity and resistance to salt damage

Abstract

This dissertation is an investigation of water movement and the associated salt damage in mortar mixes, in order to determine compatibility with a specific substrate, in this case the local building stone, Globigerina Limestone. This research focuses on mixes wherein hydraulic properties are achieved by means of the traditional methods of adding pozzolanic admixtures to lime was made. Three different admixtures were selected - natural pozzolana, crushed pottery and Pulverised Fuel Ash (PFA). Nine mortar mixes were prepared using the raw materials and methodology being taught locally by conservators to students and on-site workers alike. The mixes presented a combination of the three hydraulic admixtures and varying binder to aggregate (B:Ag) proportions as well as the addition of stone dust for increased workability, as is often done locally. The mixes were each tested for their aesthetic compatibility, water absorption and porosity characteristics as well as their durability to salt crystallisation. Simultaneously, each of the mixes was applied on the three types of Globigerina Limestone: safra, bajda and soil and these "systems" were run through the same testing programme.