GLI INTONACI NELLE OPERE DELL’ARCHITETTO GAETANO CIMA: UN ESEMPIO EMBLEMATICO DI DURABILITÀ

P. Meloni 1,2, A. Farci 1,2, G. Carcangiu3, S. Enzo4, F. Secchi 5, O. Cocco 1,2

1 Dipartimento di Ingegneria Meccanica, Chimica e dei Materiali, Università degli Studi di Cagliari, Piazza d’Armi, 09123 Cagliari, Italy, meloni@dicm.unica.it

2 Università degli Studi di Cagliari, Laboratorio Colle di Bonaria, Via Ravenna snc, 09125, Cagliari, Italy, meloni@dicm.unica.it

3 IGAG–CNR - Istituto di Geologia Ambientale e Geoingegneria, Sezione di Cagliari Piazza d’Armi, 09123 Cagliari, Italy, gianfranco.carcangiu@cnr.it

4 Dipartimento di Chimica e Farmacia, unità INSTM, via Vienna 2, 07100, Sassari, Italy, enzo@uniss.it

5 Dipartimento di Scienze Botaniche, Ecologiche e Geologiche, Università degli Studi di Sassari, Via Piandanna 4, 07100 Sassari, Italy, secchig@uniss.it

ABSTRACT

The study on plasters of historic buildings may be of great importance in order to even propose these mortars in restoration and ensure a perfect compatibility between ancient and modern materials. The plasters designed by Gaetano Cima, the most important sardinian neoclassic architect, are a prime example of how carefully chosen materials together with the accuracy of the laying and testing on site rise to products of special quality and durability. From the analysis of historic buildings in the city of Cagliari, the subject of recent restorations, it is clear that the durability of these products is greatly reduced also with the choice of mortars generally premixed that in the mix design approach those traditional. In this case the mode of execution as regards in particular the beating techniques, compaction, counterbore and, of course, timing plays a critical role. In the present work we considered samples of plaster attached to one of the most significant buildings in Cagliari, the Nuovo Spedale Civile. Microscopic, microstructural and chemical investigations of these samples were performed in order to identify the constitutive materials and techniques of realization. Information obtained from these investigations have led to a critical reading of writings that are part of the so-called “Carte del Cima”. In particular we highlighted some similarities and differences from the original formulations that have not had decisive influence on the durability of the mortars.

Key-words: mortar, durability, lime, pozzolanic reaction, cocciopesto