Characterization of building materials and alteration processes in the buildings of di monastic site at Zice

This paper concerns the scientific study of pointing mortars coming from the Saint John the Baptist’s church (Žiče Charterhouse, Slovenia). Textural and compositional data of both aggregate and binder fractions have been collected through optical microscopy, point counting, mineralogical X-ray powder diffraction analysis, scanning electron microscopy combined with microanalysis and X-fluorescence bulk chemical analyses. All these mortars, dating from Romanesque to Gothic age, have a constant aggregate composition consistent with local dolostone outcrops. Dolomitic aggregate was obtained from natural cataclastic carbonate breccias in proximity of faulted or shared zones. Local limestones and dolostones have been used through time for the binder production, obtaining building materials of high technical performances. Despite the remarkable constant composition of the mortar mixtures, the statistical analysis of the complete set of data allowed the identification of four main groups of building materials linked to probable different building phases, attributed on the bases of archaeological and architectural evidences. The alteration of the stones has been also characterized.