Atmospheric corrosion of quaternary bronzes (Cu-Sn-Zn-Pb): laboratory tests (accelerated ageing in wet & dry conditions)and field studies (the Bottego monument in Parma, Italy).

The interactions between outdoor bronzes and the environment, which lead to bronze corrosion, require a better understanding in order to design effective conservation strategies in the Cultural Heritage field. In the present work, investigations on real patinas of the outdoor monument to Vittorio Bottego (Parma, Italy) and laboratory studies on accelerated corrosion testing of inhibited (by silane-based films, with and without ceria nanoparticles) and non-inhibited quaternary bronzes are reported and discussed. In particular, a wet&dry ageing method was used both for testing the efficiency of the inhibitor and for patinating bronze coupons before applying the inhibitor. A wide range of spectroscopic techniques has been used, for characterizing the core metal (SEM+EDS, XRF, AAS), the corroded surfaces (SEM+EDS, portable XRF, micro-Raman, ATR-IR, Py-GC-MS) and the ageing solutions (AAS). The main conclusions were: 1. The investigations on the Bottego monument confirmed the differentiation of the corrosion products as a function of the exposure geometry, already observed in previous works, further highlighting the need to take into account the different surface features when selecting conservation procedures such as the application of inhibitors (i.e. the relative Sn enrichment in unsheltered areas requires inhibitors which effectively interact not only with Cu but also with Sn). 2. The ageing (pre-patination) cycle on coupons was able to reproduce the relative Sn enrichment that actually happens in real patinated surfaces, making the bronze specimens representative of the real support for bronze inhibitors. 3. The non-toxic silane-based inhibitors display a good protective efficiency towards pre-patinated surfaces, differently from other widely used inhibitors such as benzotriazole (BTA) and its derivatives. 4. The 3-mercapto-propyl-trimethoxy-silane (PropS-SH) additivated with CeO2 nanoparticles generally offered a better corrosion protection than PropS-SH.

Aereodynamics of dry helically-filleted bridge cables

Dry limited amplitude vibrations flow-transition induced vibrations were experienced on a helically-filleted tube, in a previous study performed by Kleissl and Georgakis (2012). These vibrations have never been reported in previous studies. A deep study on the same inclined-yawed cable configuration has been performed, in order to investigate and further understand the nature of these vibrations. The investigation has been carried out through passive-dynamic wind tunnel tests in the Climatic Wind Tunnel at FORCE Technology, Kgs. Lyngby, Denmark. The results are carried out in terms of aerodynamic damping and peak to peak amplitude at different flow velocities and different boundary conditions. The latter are done by testing the model with and without the spray system installed in the wind tunnel cross section, in order to understand and evaluate the influence of the spray system on the start of the vibrations mechanism and on the flow turbulence. The gained experiences are finally presented for the use in future testing activities with the purpose of improving the performance of passive-dynamic tests.

Strength development of single beech wood veneers considering different climate conditions

La tesi di laurea è stata svolta presso l’Università di Scienze Applicate di Rosenheim, in Germania; il progetto di ricerca si basa sulla tecnica di rinforzo conosciuta come “Soil Nailing”, che consiste nella costruzione di un’opera di sostegno nella realizzazione di pareti di scavo o nel consolidamento di versanti instabili. L’obiettivo principale dell’elaborato sarà quello di valutare la fattibilità dell’impiego di tubi fabbricati con legno di faggio, in sostituzione dei chiodi d’acciaio comunemente utilizzati; la scelta di questo tipo di legno è dettata dalla larga disponibilità presente in Germania. La sollecitazione principale su tali tubi sarà di trazione parallela alla fibratura, tramite test sperimentali è stato possibile valutare tale resistenza nelle diverse condizioni in cui si verrà a trovare il tubo dopo l’installazione nel terreno. A tal proposito è necessario specificare che, l’indagine per risalire all’influenza che le condizioni ambientali esercitano sull’elemento, verrà condotta su provini costituiti da un singolo strato di legno; in tal modo si può apprezzare l’influenza direttamente sull’elemento base e poi risalire al comportamento globale. I dati ottenuti dall’indagine sperimentale sono stati elaborati tramite la teoria di Weibull, largamente utilizzata in tecnologia dei materiali per quanto riguarda materiali fragili come il legno; tali distribuzioni hanno permesso la determinazione della resistenza caratteristica dei provini per ogni condizione ambientale d’interesse. Per quanto riguarda la valutazione della fattibilità dell’uso di tubi in legno in questa tecnica di consolidamento, è stato eseguito il dimensionamento del tubo, utilizzando i dati a disposizione ottenuti dall’indagine sperimentale eseguita; ed infine sono state eseguite le verifiche di stabilità dell’intervento.