Le murature nell’architettura del versante meridionale del Gran Sasso (secc. XI-XIV)

Aim and subject of the research is the constructive techniques of the masonries, employed benveen the XI and the XIV century, in the architecture of the soutli side of the Gran Sasso. Techniques and materials are studied in order to investigate the constructive and architectural qualities of the historical masonries. The objectives are: to pick up data about masonries, studied as documents characterized by an own evidence value; to correlate the technological characteristics with the historical and architectural values; to connect constructive characteristics with chronological references. The research is related to studies on traditional building techniques, made by Architecture and Town Planning Department of L'Aquila University. The territory of the south side of Gran Sasso is defined by the synthesis of geo-morphological characteristic and men's modifications. Different buildings' kinds can be correlated to the process of "fortification", as walled towns, enclosure-walls, towers, castles, strongholds, fortified palaces, castle-residences. These structures are characterized by historical stratification, frequently by notable transformative processes connected to the reuse as habitations. The stratification, witness element of historical and architectonical values, make the direct inquire determinant, especially for the scarcity of docuniental data. If we take in consideration technological characteristics, the study of masonry is based on the analysis of stone's material, of morphology, working and size of components, on modality of assembly. Nevertheless masonries have aesthetical qualities, especially if they are not plastered. The architecture is characterized by its own materials. The oriental region presents compact lime stones, the west region marls; sometimes there are sandstones. The stones have different colours: the lime stones are white, beige, pink and red; the marls are grey, ochre and brown. The colours of the historical cities are often related to other factors, such as biological crusts. The kind of stones used in masonry shows that usually the quarry is near the building. Ancient rornan buildings have often been used as caves; the use of ancient stones concerns all the greatest factories of the territory. The morphology of the stones is connected to the characteristics of the material and to the submitted works. It's proposed a classification of the stone's elements, based on the kind of materials, morphology, dimensions and finishing. The region is poor of clayey grounds, so the use of bricks is limited. They are used as inserts in masonries. Near the ancient roman buildings, perhaps the bricks originate from the ruins. The mortars are entirely constituted by calcium carbonate, with aggregates produced by shattering the stones in site. We can fìnd better gradation-curves in religious buildings. We have the following kinds of stone's assemblage: irregular, with irregular courses, with doubled or convergent courses, with undulated courses, with sub-horizontal courses, with horizontal and parallel courses. Parameters for the individualization of classes of hangings are: the kind of stone material; the kind of element; the dimensions and morphology of the elements; their finishing; the kind of assemblage. The nucleuses of masonries can be divided in four classes: nucleuses made with elements inserted among tlie hangings; nucleuses with constipated material; nucleuses with casting of the elements; masonries with a cut-stone's facing of the wall. The masonries are classifìed according to the hangings and to the kind of nucleus. Through a comparative analysis, the classification allows to indicate affinity among the masonries of different buildings. The definition of masonry's kinds and the construction of a comparative matrix, give the possibility to compare masonries, locations and chronological data. Analyzing the variation of the stones dimension for the so called apparecchio aquilano, we can indicate a reduction of their dimensions from the XII century to the beginning of the XIII century; the ineasures are constant or decrease during the XIII century; they are constant or increase from the end of the XIII century. The chronological matrix indicates that masonries made with irregular stones are datable among the XIII and the XIV century; masonries made with regular draft stones are present from the XII to the XIV century; masonries made with small ashlars persist from the XI century to the XIV century; the typologies in cut-stones are attested around the XI-XIII century.