Use of the reinforced concrete in the preservation of historical buildings: conceptions and misconceptions in the early 20th century

This article analyzes the cultural and technical reasons that led to the widespread use of reinforced concrete in the restoration of monuments in the first half of the twentieth century (1900–1945). The restoration theories of the epoch, affirming the concept of conservation and recognisability of the interventions, supplied theoretical legitimacy for the new material. The assertion of a new concept of safety, based on models and quantifiable parameters, and its public recognition, led the state to attribute the responsibility for the safety of monumental buildings to the new technical class of engineers. The affirmation of this technical class coincided with the abandoning of the traditional art of building, but, at the same time, with the abandoning of research into and experimentation on masonry structures. The lack of knowledge that resulted from this, together with an unlimited confidence in new building systems, were the basis for many of the interventions in reinforced concrete carried out in that epoch. This article includes an analysis of the cultural and technical reasons that led to the widespread use of reinforced concrete in restoration, a description of its technical evolution, starting from the very first applications to appear at the great consolidations of the 1930s, and, finally, a detailed analysis of two case studies (the tower of San Antonino in Piacenza and the San Gaudenzio basilica in Novara). Particular reference is made to Italy.