Applied mineralogy in the study of historical lime mortars

Résumé

This PhD thesis aims to contribute towards a better understanding and conservation of ArchitecturalHeritage through applied mineralogy in the study of historical lime mortars. To achieve this aim theresearch approaches the study of the lime mortars from different historical buildings in northern Spain,by combining a series of mineralogical, chemical and physical analytical techniques. Aggregates naturein the studied mortars differed in each historical building and depending on the building structurespointing to a specific selection of the raw materials, which are mainly conditioned by the surroundinggeological materials. Sample preparation and the accurate mineralogical characterization of mortarbinder have been essential to achieve more reliable radiocarbon ages. It has been demonstrated that thelayered double hydroxides phases (LDHs) constituted a potential contaminant mineral phase for mortarradiocarbon dating. The obtained results also provided valuable information about technologicalknowledge in mortar manufacture and application techniques, such as the use of both the traditionalhot-mixing method in the manufacture of mortars and the multi-layering application technique. Thehigh porosity and water absorption capacity, poor pore interconnection or difficulty in drying have beenthe main causes for studied lime mortar deterioration susceptibility, although environmental conditionsto which are exposed also makes them susceptible to potential water and salts damage. The presentstudy lays the foundations for the design of repair mortars that ensure the conservation of studiedcastles in future restoration works.