Effect of silica fume additions on the hydration behaviour of calcium aluminates

In the recent refractory castables technology, the calcium aluminate cement is being replaced in increasing proportion by very fine matrix components, such as silica fume and colloidal alumina. More efficient particle packing and the resulting lower water requirements have been the proposed explanation for the improved green density and strength, without sacrificing the castable workability. However, the aluminates are still responsible for the hydraulic setting of the castable. The hydration mechanisms of single calcium aluminates, and mixtures thereof, synthesised by combustion reaction of the appropriate nitrate-urea mixtures, were recently investigated. The present work describes the effect of silica time additions on the hydration behaviour of pure single calcium aluminates, also produced by combustion reaction. Results on the hydration mechanisms, the microstructure development and the resulting physical and/or mechanical properties of the hydrated samples, as a tiction of the water/cement ratio and the silica content, me presented and discussed.JNICT-Portugal - PALOP/24

PAESAGGI CULTURALI Artificio tra resilienza e selezione naturale

Over fourteen thousand and up to twelve thousand years ago, due to a serious food supply crisis, homo sapiens implemented a new model of survival based on agriculture, starting to sow, man became more sedentary. Nowadays, we rely on a new adaptation process to bring us closer to farm and craft activities, reviving small scale settlement systems. Knowing the peculiar features of a natural or urban artificial landscape and identifying in it with a feeling of belonging, as a place bearing culture and traditions, has always linked the human beings to their territory, to a geographical context. In the current global environmental crisis, the rural landscape is once again considered an asset for man, especially for its cultural and spiritual values, as a fundamental scenario to build individual and collective life. Therefore, for every human community, the whole landscape becomes a place where to reside, live, build, produce, sell, pass on, it participates in the whole cycle

Scuole come incubatori civici

Gli edifici pubblici destinati all’educazione scolastica dovrebbero costituire un obiettivo prioritario nelle strategie di sviluppo nazionale, regionale e locale, ma anche in passato è accaduto che venissero varate leggi inerenti nuovi metodi di insegnamento e di formazione senza considerare che alle nuove modalità didattiche e alle nuove attività dovessero corrispondere nuovi differenti spazi. Se la più evoluta pedagogia ci annuncia da molti decenni che l’istruzione e la formazione non avvengono solo ed esclusivamente tramite lezioni frontali ex catedra, ciò dovrebbe significare che gli spazi scolastici dovrebbero essere strutturalmente innovati e subire una reale metamorfosi funzionale. L’edilizia scolastica dovrebbe essere al centro delle azioni politiche strategiche nazionali se non può esserci polis senza la scuola come veicolo di trasmissione culturale tra generazioni, nella consapevole partecipazione delle nuove generazioni al processo di cambiamento della società urbana. Le nostre scuole pubbliche devono trasformarsi in Civic Center, come ci indica chiaramente il Decreto Ministeriale del 2013, appropriandosi del ruolo associativo ed identitario che nel nostro cattolico Paese è stato troppo a lungo delegato ai soli enti religiosi che hanno assolto questa carenza dell’istituzione laica, con lodevole spirito di servizio pubblico. Scuole come ‘incubatori civici’, ovvero scuole educanti ovvero edifici scolastici educanti. Come realizzare questo obiettivo se non attraverso la percezione di un progetto rispettoso delle risorse ambientali

Seismic rehabilitation of cultural heritage masonry buildings with unbonded fiber reinforced elastomeric isolators (U-FREIs) \u2013 A case of study

In order to assess the structural behavior and to evaluate the seismic vulnerability of masonry structuresof relevant historical and artistic significance, which is a widespread building type in Italy and in the world,an historical masonry church is analyzed under earthquake loading. Linear and non-linear analyses areperformed on the finite element models of the structure. From these analyses it is pointed out that thestructure does not behave elastically in its existing condition even when subjected to the frequent designearthquake (81% probability of being exceeded over 50 years). Two traditional rehabilitation methods arestudied: the placement of a rigid diaphragm which connects the top of the masonry walls only enclosingthe church entrance area and the placement of a rigid diaphragm which connects the tops of all masonrywalls. None of the traditional method is sufficient for the structure to survive basic design earthquake(10% probability of being exceeded over 50 years). Hence an advanced seismic retrofit solution usinginnovative carbon fiber reinforced elastomeric isolators is proposed. The proposed intervention consistsin the installation of six Unbonded Fiber-Reinforced Elastomeric Isolators (U-FREI) and six Flat SurfaceSliders (FSS) as passive protective devices besides the placement of a rigid diaphragm which connects thetops of all masonry walls. The process of installation of the devices is illustrated. The use of the proposedsolution leads to a remarkable enhancement of the seismic response capacities of the structure; indeeda general elastic response under the Basic Design Earthquake (BDE) is attained

Leg ulcer in Werner syndrome (adult progeria): a case report

Werner syndrome (WS; MIM#277700) or adult progeria, is a rare disease, associated with mutations of a single gene (RECQL2 or WRN), located on chromosome 8 (8p12). It codes a DNA-helicase, whose defects cause genomic instability. The highest incidences are reported in Japan and Sardinia (Italy). On this major island of the Mediterranean Basin, the WS cases have been observed in the northern areas. The authors describe the apparently first case reported in southern Sardinia, a 51-year-old woman, who was born in and resides in the province of Cagliari. She presented with a 9-year history of an intractable leg ulcer and other characteristic symptoms, including "bird-like" face, high-pitched voice, premature greying, short stature, abdominal obesity in contrast with thin body type, scleroderma-like legs, decreased muscle mass, diabetes, atherosclerosis, and premature menopause. A specialized genetic Institute of Research (IRCCS-IDI, Rome) confirmed the clinical diagnosis. There is no cure or specific treatment and patients must be periodically screened for an increased risk of cardiovascular and cerebrovascular disease and malignancies. Among the many findings, leg ulcers significantly affect the patient's quality of life. This problem may send the patient to the dermatologist, who finally suspects the diagnosis. Poor response to medical treatment may require aggressive repeated surgery, with poor or temporary results

Famous architectures in urban contexts: the impact of colours and materials

Architecture is not just a container or a place in which it is possible to perform functions; architecture is everything that surrounds us, it is the space in which we immerse ourselves and with which we communicate. It is not the shape of the project that first influences our perception of space, whether it is open or closed, but the colours and materials that characterise and define it, making it harmonious and pleasant or, in the opposite way, hostile and inhospitable. In 1981 the UNI 8289:1981 "Construction. Needs of the final user. Classification" defined the term "well-being" as "the set of conditions relating to states of the building system appropriate to life, to health, to the performance of the users' activities", how do colours and materials contribute to the conditions of well-being? Which are the targets that can be achieved through the wise use of these elements? The aim of this work is to analyse the application of colours and materials in famous architectures in order to determinate the impact at urban and human level, how they dialogue with the context and how they dialogue with human perceptions, identifying three directions of intervention: colour and materials as anthropomorphic relation, colours and materials as pictorial support, colour and materials as function

Interlaminar Response of LSI-Produced C/SiC Ceramic Matrix Composites: Experiments and Modelling

This work investigates the interlaminar properties of a C/SiC composite produced by Liquid Silicon Infiltration, combining experiments based on Double Cantilever Beam tests and numerical analyses. Experimentally, a method to obtain pre-cracks with sharp tips at precise locations is proposed, and specimens with different thickness are used to investigate the effects of bending stress states in the delamination process. The properties of tri-linear Cohesive Zone Models for the modelling of delamination are identified numerically, by using automatic regression techniques without requiring additional assumptions or testing. Fiber bridging effects were observed and modelled, including the evaluation of the process zone lengths with different experimental, analytical, and numerical methods. Overall, the work provides a qualitative insight in the delamination process of long fiber reinforced C/SiC laminates produced with a cost-affordable technique and proposes an experimental and numerical protocol to characterize and model delamination phenomena, taking into account the scattering of material properties

Demolition or renovation? A controversial case in Pozzuoli

Demolizione o ristrutturazione? La scelta può essere un compito complesso, dovendo considerare l'iniziale condizioni e prevedere il futuro Scenari. Anche se la rigenerazione degli organismi edilizi potenziale è molteplici, la tecnologia e sistema di costruzione può svolgere un ruolo decisivo la determinazione della fine del loro ciclo di vita, a causa di i costi di ristrutturazione e strutturale l'adattamento all'energia. Oltre all'economia valutazioni, politiche, storiche e sociali motivazioni sono coinvolte, o in alcuni casi sono mettere al primo posto. Pertanto, la fase finale di un la vita dell'edificio non è sempre indiscutibilmente determinabile; Esistono due scenari possibili che sono spesso delineati in una condizione di inefficienza funzionale: Demolire o Ristrutturare. Attraverso l'applicazione di due approcci, il progetto di demolizione e progetto di ristrutturazione Per stesso caso di studio a Pozzuoli, è possibile evidenziare le potenzialità, i vantaggi e le conseguenze dei due diversi modi di Azione