Gli impasti cementizi in Italia nel primo Novecento. Percorso di conoscenza del materiale per la definizione di suggerimenti operativi in fase di restauro.

In recent years, a growing attention is spreading towards the Twentieth Century architecture which encloses, in the typological and technological innovation, its cultural value, but at the same time it contains major conservation problems derived from high level of testing of the materials utilized. In particular, cement mixes, combined or not with iron, show incredible malleability and ease of processing, characteristics that guarantee success in the Art Nouveau period (examined in this research); later, with the spread of rationalist architecture, testing is implemented, introducing on the market conglomerates and mixtures cement-based, innovative products such as symbol of 'durability', mainly used for the realization of bold structures that exceed the constructive logics possible up to that moment. However, the enhanced durability and strength of the cement, both of the products with structural function and of refined decorative elements reveal currently their limits, so many buildings have expressed the need of adeguate restoration. In spite of the protection of many Twentieth Century public buildings, according to the "Code of cultural heritage and landscape" - Legislative Decree n. 42/2004, it is still evident the lack of attention, about the materials set, during the planning in the restoration of modern buildings. In fact, unlike the oldest buildings, currently operating decisions aim to the reuse of the building, without paying attention to the cultural values of the materials of the construction1. Waiting for the attention to modern materials will face more and more careful, nowadays the legislation does not provide useful addresses to the designer: so the preservation of Twentieth Century materials depends on the attention of the technician and the client who, hurried by the degradation and the urgency of the intervention, work without any suggestion of restoration specialists. The research starts by studying the manuals and documentation of archive concerning with patents and performance techniques of historical mixes, with the aim of identifying those most prevalent during the examined period. This is followed by the analysis of sixty-three case studies, essential to know the characteristics of the Twentieth Century mixtures set in place and their degradations. The selected buildings, realized between 1900 and 1918 and with different conservation problems, are located between Emilia Romagna and bordering regions and have mostly residential function. For each building were collected different types of data, classified in order to provide a basis for further processing of interpretation. These evaluations aim to put into relation the degradations with several factors affecting the cement mixtures. The result of these evaluations, as well as the first product of the research, consists of preparing the 'degradations sheets' relative to cement mixes used in Italy during the period examined. Subsequently restorations on architectures of the early Twentieth Century were identified, so it was possible to analyze the different approaches currently in use in the construction phase, including techniques, materials and conservative principles. Speaking about this, it is useful to consider also the construction sites of national and European research projects which study similar issues, allowing a comparison of the different practices, but also a better understanding of the current research level in this field. The study concludes with the drafting of the final product of research, that is operational suggestions useful to correct any phase of restoration, which lead to conservative choices respectful both of safety requirements, and the cultural meanings of the material, relevant for technological innovation expressed in material essence and aspect. This product is for technicians and enterprises that, in designing and construction phases, approach to the conservation of historic buildings made of cement. The large number of constructions realized with these materials, that in the near future will be identified as cultural heritage, requires appropriate restoration practices, providing a useful and consistently tool to work for the Twentieth Century architectures. --------------- 1 MONTANARI G., Cosa conservare dell’architettura contemporanea?, in: CALLEGARI G., MONTANARI G. (edited by), 2001, pp. 29-35.