Characterization of “Terranova” render samples as a contribution to XX century heritage conservation

The “Terranova” render was a ready-mix dry coloured mortar which diffused in Europe in the first half of the XX Century. During the 1920s and 1930s, it was largely adopted in Italy as a finishing solution for the façades of rationalist architecture. It quickly became very popular thanks to its excellent aspect and high durability. Despite its wide diffusion, its formulation and technical properties remain basically unknown, also due to some patents protecting it. For this reason, Terranova renders are often not recognized in restoration interventions. In this study, different samples of supposedly Terranova render were collected from three rationalist buildings in Ferrara and Forlì (Italy) dating back to the Thirties and a thorough characterization was carried out to investigate their formulations and features. A comparison was also made with a Terranova sample collected from a rationalist building in Bologna (Italy), analysed in a previous study. The aim was to characterize this material and disclose, if existing, a recurrent formulation, to explain its outstanding properties and advance the design of compatible repair mortars. Despite the recurrence of some features, defining a common formulation seemed to be hard, suggesting that alternative recipes were used in manufacturing this industrial render.