Conservation issues of exposed reinforced concrete in the Italian motorway bridge-restaurants of the late 20th century

The development of Italian motorways between 1955 and 1975 represents one of the symbols of the post-war national renaissance and the result of profound socio-economic changes. The construction-sites also became a stimulating workshop for architectural and engineering experimentation. The diffusion of concrete building techniques played a crucial role in the infrastructure construction sector (bridges, viaducts, overpasses, etc.), but also in the design of relevant buildings along the motorways. The paper aims to analyse how this material was used in such buildings and to examine the critical/operative issues related to its conservation. The research concerns case studies (the bridge-restaurants in Novara, Brembo, Dorno and Limena) which highlight three research perspectives linked to the conservation of concrete structures. These buildings are thus compared to point out how the expressive possibilities of this material/technique and the figurative features of concrete structures were crucial for their design. The lack of a collective acknowledgement of these buildings within the 20th- century heritage has thus led to a considerable modification of the previous features. The study identifies the main problems in the conservation/preservation of these structures, which have profoundly changed over time to respond to regulatory, energy and marketing needs. Recent interventions on these buildings have not usually affected the overall behaviour of the structures, but they have focused in particular on their surfaces by changing relevant characteristics of the original design idea. In some cases, the buildings have been hidden in new shells which prevent the early façades from being seen. Only a meticulous investigation could make them re-emerge from the state of serious modification or damage that they have suffered till now. Their preservation is firstly related to the protection of the existing structures, but it should be also regarded as a constant knowledge process and an opportunity for new appropriate projects. The future conservation design should reconcile the current requirements with the values of the original building, primarily by considering the different codes related to the use of reinforced concrete.