Le volte campane estradossate da Amalfi all'Arcipelago Campano. Applicazione nella Certosa di Capri

In the Sorrento-Amalfi peninsula and in the Naples islands, a long tradition of building culture exhibits the influence that the permanence of ancient constructive techniques have had on the building types which define and characterize the historical landscape. This is the case of the marked relations regarding masonry building typologies and their roofing based on extradosed vaults. This kind of vaults had its first diffusion at least starting from the Anjou period. The paper proposes the results of an investigation on this system conducted particularly through the architectural, chemical and mechanical surveys of existing works in the Capri area. Considering the state of art on the constructive technique, the study documents a constructive praxis and materials characterization. The main outcomes concern the definition of the relations existing between construction and aggregates structural behaviour, and the multiscale interferences characterizing constructive technique, architecture and landscape. The vaults, named “a gaveta” are constituted by the disposition of irregular limestones filled using a lime concrete enriched with pozzolana, their extradosed and waterproofed by the use of the ”astrico battuto”, diffused in urban and rural area of the island of Amalfi coast, both in the common buildings and in monumental complexes”. The vault, built on a mould, was realized by limestones, thin 16-18 cm, and waterproofed by a layer of volcanic sand and lime mortar, which it has been bumped and compacted until the thin of 15 c.. Rondelet, writing in his Traité about the definition of the “Lastrico”, reports: “made by little broken pieces of pumice and burnt tuff […] little stones smaller than a nut”. Among several cases of study we highlight the Chartreuse of Capri, where we note how the typical chartreuse plan is treated, in the island landscape, according to extradosed volumes hierarchy. The strength of volumetric solution has permitted, in centuries, to disregard other ornaments. The constructive technique configures the chartreuse as a landmark:”in the Chartreuse there is also to highlight the symbolic meaning of the cross vaults, adopted in the roofing of church, refectory and monks cells. These make the different rooms well far distinguishable”. Finally the investigation has also permitted to the groups of the two university involved to confirm e define elements of a pre-modern science of construction where materials shows the consciousness of structural behaviour in ancient constructors.