Le formelle del palazzo ducale di Urbino: nuove interpretazioni

Viene giustificata la scelta del numero 72 delle formelle come ricordo della scomparsa di Battista Sforza, di Battista Alberti e Giovanni Bessarione avvenuta nel 1472. Il confronto fra il contenuto delle formelle ed i primi 53 disegni del codice della B.A.V. Urb. Lat. 1377 permette di considerare due distinte fasi della composizione del fregio. Una prima stesura del fregio (con notevoli differenze stilistiche), viene identificata in continuità con l’idea dell’Alberti, esposta sugli zoccoli dei pilastri, dove sono esposti scudi romani con lance incrociate. In queste formelle Federico, come riconosciuto dal Bianchini, che l’ornamento più proprio di una tal fabbrica fossero gl’istromenti medesimi delle di lui vittorie, e del suo ingrandimento, ha la sua gente armata sulla quale si basa (sulla quale conta), rappresentata attraverso le loro armi, come se i suoi fossero pronti ad indossarle per seguirlo, come fossero quelle ben lucidate e lubrificate che si dice «sostassero» all’interno del portico del palazzo. Ci sono rappresentati, come direbbe Machiavelli : i fanti con lo scudo, i fanti con la picca, i capidiedi colla picca, i capidiedi con lo scudo, i veliti ordinari, i veliti straordinari, i centurioni, i centurioni delle battaglie, il capo del battaglione, il capitano generale, il suono, la bandiera, gli uomini d’arme, i cavalli leggeri, l’artiglieria. Accostando le idee neoplatoniche alla colta corte urbinate, si scoprono le sequenze evolutive del pensiero materializzate nella evoluzione delle macchine e si portano argomenti per comprendere lo studiatissimo disordine proprio della stesura di questa così pioneristica opera d’arte

Evaporation of aqueous salt solutions in sandstone during dissolution/crystallization cycles

COMInternational audienc

FINITE ELEMENT ANALYSIS FOR THE PREDICTION OF THE CIRCUMFERENTIAL BAMBOO STRENGTH

Reported theoretical analyses have not explained the variation with radius of the circumferential strength of bamboo. This study aims to analyze this issue using finite element analysis. A rectangular image representative of the culm cross section of Phyllostachys edulis was divided along the radial direction into ten parts. Next, ten FE rectangular models representing the fibers, matrix, and void content at each radial position were generated. The matrix and the fibers were assumed to be isotropic, having elastic moduli of 1800 MPa and 18000 MPa, respectively. The strength predicted with the fiber first principal stress is parabolic along the radial direction, consistent with experimental findings

Thermal treatment of bamboo with flame: influence on the mechanical characteristics

The mechanical properties of bamboo are susceptible to degradation due to both physical and biological agents. Among the non-chemical treatments, we studied the influence of a short-time heat treatment, using an LPG-gas torch, on the mechanical properties of a bamboo (Phyllostachys viridiglaucescens) growing in Italy. The response was very encouraging as we found no significant reduction in either elastic modulus or tensile, compressive and bending strength. Several samples were subject to tension, compression and bending tests to compare the responses of the treated and untreated culms. The average tensile elastic modulus was slightly greater for the untreated culms. The average tensile strength of the untreated culms was only slightly greater, and the differences can be assumed to be insignificant from a structural point of view. The average value of the treated culms compressive elastic modulus was slightly greater than that of the untreated ones. The compressive strength was essentially the same. The bending mechanical behaviour was barely influenced by the thermal treatment. A microscopic investigation (optical and electron microscopy) was undertaken to investigate the possible deterioration of the bamboo microstructure due to the heat treatment. No appreciable damage was detectable in the treated material. The proposed heat treatments can be considered as a reliable and sustainable protection practice for bamboo culms

A feasible re-use of an agro-industrial by-product: Hazelnut shells as high-mass bio-aggregate in boards for indoor applications

The present work investigates the feasibility of producing boards, with unconventional materials, namely hazelnut shells as a high-mass bio-aggregate and a sodium silicate solution as a no-toxic adhesive, and discusses possible applications based on an extensive characterization. The aim is to define a feasible reuse of a largely produced agro-industrial by-product to reduce the high environmental impact caused by both the construction and the agriculture sectors, by proposing a building composite that improves indoor comfort. The presented combination of aggregate-adhesive generated a product with characteristics interesting to explore. The thermal conductivity is moderated, and the composite achieved values of σmax = 0.39 N/mm2 for flexural strength and σmax = 2.1 N/mm2 for compressive strength, but it showed high sorption capacity with a moisture buffering value of about 3.45 g/(m2 %RH), and a peak of sound absorption between 700 and 900 Hz. Therefore, the boards’ most promising performance parameters seem to be their high hygroscopicity and acoustic absorption behaviour, namely in the frequency range of the human voice. Hence, the proposed composite could improve indoor comfort if applied as an internal coating board.info:eu-repo/semantics/publishedVersio

A solution to improve indoor comfort

This research was funded by the Portuguese Foundation for Science and Technology (FCT- Fundação para a Ciência e a Tecnologia), with Ph.D. grant PD/BD/150579/2020, as part of the Eco-Construction and Rehabilitation Program (EcoCoRe). The authors acknowledge Matteo Cingolani for carrying out the acoustic analysis, the technicians of LISG and DIN Labs of the University of Bologna for their help in the laboratory tests; Mirko Braga (Ingessil S.r.l) for his help and suggestion to use sodium silicate solution as an adhesive; Stefania Liuzzi and Francesco Martellotta (Polytechnic University of Bari) to provide suggestions to carry out the research; Anna Rovigatti for the important support for the acoustic analysis. Publisher Copyright: © 2023 The AuthorsArundo donax (giant reed or giant cane) is a widely available, perennial, invasive, non-food crop, present worldwide and employed for several uses, including building practices. Considering the increasing demand for sustainable building materials, A. donax can be an efficient solution. This study investigated its properties as a bio-aggregate mixed with a sodium silicate solution as an adhesive. A horizontal analysis that provided a general characterization of the composite was carried out. The results showed that the A. donax-based composite had an apparent density of 517 kg/m³, thermal conductivity of 0.128 W/(m.K), and high hygroscopicity, with a moisture buffering value of 4.33 g/(m² %RH), property that could be both an advantage for indoor comfort and a drawback. The uncommon sound absorption behaviour can be comparable to granular materials, with the highest sound absorption coefficient values, α, between 600 Hz and 700 Hz. Due to the range and the shape of the acoustic absorption property, this material may be helpful in acoustic treatments for speech noise. The mechanical tests defined flexural and compressive strength, respectively, 0.35 N/mm² and 0.9 N/mm², ensuring applicability. Above all, these tests opened new possible solutions for A. donax-based composite production either alone or in combination with other agro-industrial wastes and justified further tests, such as fire resistance and bio-susceptibility.publishersversionpublishe

Characterization of an Arundo donax-based composite: A solution to improve indoor comfort

ABSTRACT: Arundo donax (giant reed or giant cane) is a widely available, perennial, invasive, non-food crop, present worldwide and employed for several uses, including building practices. Considering the increasing demand for sustainable building materials, A. donax can be an efficient solution. This study investigated its properties as a bio-aggregate mixed with a sodium silicate solution as an adhesive. A horizontal analysis that provided a general characterization of the composite was carried out. The results showed that the A. donax-based composite had an apparent density of 517 kg/m³, thermal conductivity of 0.128 W/(m.K), and high hygroscopicity, with a moisture buffering value of 4.33 g/(m² %RH), property that could be both an advantage for indoor comfort and a drawback. The uncommon sound absorption behaviour can be comparable to granular materials, with the highest sound absorption coefficient values, α, between 600 Hz and 700 Hz. Due to the range and the shape of the acoustic absorption property, this material may be helpful in acoustic treatments for speech noise. The mechanical tests defined flexural and compressive strength, respectively, 0.35 N/mm² and 0.9 N/mm², ensuring applicability. Above all, these tests opened new possible solutions for A. donax-based composite production either alone or in combination with other agro-industrial wastes and justified further tests, such as fire resistance and bio-susceptibility.info:eu-repo/semantics/publishedVersio

Impact of recrystallization cycles on drying of salt contaminated porous media

COMInternational audienc

A solution with good performance in case of fire

If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. The authors acknowledge Jacopo Ortolani for carrying out the test for fire reaction, and the technicians of LISG Lab of the University of Bologna for their help in the production of the samples. The authors also acknowledge Lorenzo Coraglia (Raccolti di CIN) for donating the hazelnut shells and providing important information for this research project, Prof. Silvio Salvi and Daniele Rabboni (Department of Agricultural and Food Sciences, University of Bologna, Italy) for providing A. donax; Mirko Braga (Ingessil S.r.l) for his help and suggestion to use sodium silicate solution, and Prof. Stefania Liuzzi (Polytechnic University of Bari, Italy) to give information for samples' production. Publisher Copyright: © 2024 The AuthorsThe present study investigated the reaction to fire of bio-based boards for indoor applications made of A. donax and hazelnut shells as aggregates. A sodium silicate solution was employed as the adhesive due to its several advantages. Among others, the possibility of moderating some of the main drawbacks of bio-based building composites, such as the resistance to fire. The considered materials were analysed both individually, to test their inherent properties, and when integrated into the composites, ensuring considerations about materials' influence on the final products’ properties. Two different test methods, using a cone calorimeter, were considered and performed. The results showed that the sodium silicate solution avoided flaming and smoking, in case of a constant heat application with and without an igniter (spark), demonstrating the benefit of its use in this type of bio-based composites. Overall, the particleboards demonstrated their ability to comply with fire behaviour consistent with the Class A1 requirements, while the bio-components on themselves were characterized by an intermediate fire risk propensity. Thus, the present study provided an effective solution to avoid one of the main drawbacks of bio-based composites. It demonstrated the feasibility of employing the proposed bio-based boards as indoor coating, with no risk to human life in case of fire.publishersversionpublishe

A feasible re-use of an agro-industrial by-product: Hazelnut shells as high-mass bio-aggregate in boards for indoor applications

The present work investigates the feasibility of producing boards, with unconventional materials, namely hazelnut shells as a high-mass bio-aggregate and a sodium silicate solution as a no-toxic adhesive, and discusses possible applications based on an extensive characterization. The aim is to define a feasible reuse of a largely produced agro-industrial by-product to reduce the high environmental impact caused by both the construction and the agriculture sectors, by proposing a building composite that improves indoor comfort. The presented combination of aggregate-adhesive generated a product with characteristics interesting to explore. The thermal conductivity is moderated, and the composite achieved values of σmax = 0.39 N/mm2 for flexural strength and σmax = 2.1 N/mm2 for compressive strength, but it showed high sorption capacity with a moisture buffering value of about 3.45 g/(m2 %RH), and a peak of sound absorption between 700 and 900 Hz. Therefore, the boards’ most promising performance parameters seem to be their high hygroscopicity and acoustic absorption behaviour, namely in the frequency range of the human voice. Hence, the proposed composite could improve indoor comfort if applied as an internal coating board