Historical mortars as record in the knowledge of ruins

Ruins are buildings that, for natural or human causes, have lost considerable parts of theirarchitecturalform and materials. The survivingstructures, exposed to the weather and in continuingneglect, give us the possibility to studyand to know more about the technology from the past. Especially in the artificial stones, the mortars are designed differently in each epoch according to the local manners and materialavailability.Starting from this consideration, the present research aims toillustrateas the characterisation of mortarsand the analysis of theirstate of conservation hasa valuable importance in theknowledge of a building in state of ruin.In fact, they are both a precious record that permits usto understand the materials and the traditionaltechniques of which the building wasmadeand possibly restored. They are alsoadating element to support the study of chronologies, especially when the historical archives does not have memory of documentary and photographicevidences. Moreover, theanalyseof old mortarsisfundamental to evaluate the stability of the structures and to proposean appropriate and compatible new mixture, whether for conservationorfor there-use. For these reasons, after a macroscopicin situ inspection, a reasonable sampling is done as base for the following detailed analysis. These include a first selection of thesamples, choosing the most significantfor the structures; thepetrographic study by means of transmitted and reflected light microscopy,and finally the study of the aggregate and of the binder separately with the use of the x-ray diffractometer. Case studyof this protocolis the Church of San Giovanni Battista, a ruined monument located in the rural landscape of Bortigali (Sardinia, Italy) and dated backXIII-XIV century. In this case of study, considering the lacking and inadequate presence of historical sources, mortars are been afundamental element to reconstruct the building phases of the fabric,previously uncertain.