1,720,993 research outputs found
Two different stochastic approaches modelling the decay process of masonry surfaces over time
No full textMasonry structures subjected to aggressive environment may suffer degradation during their service life; the decay strongly depends on type of the component materials and the technique of construction. This can lead the structure to high states of damage even if not failure. The great randomness connected with the occurrence of critical attacks suggests approaching the deterioration process of masonry under a probabilistic point of view. Following this way, the deterioration process L(t) of stone masonries has been carried out. It has been approached as:
1) L(t) time dependent stochastic process of the random variable (r.v.) l.
2) L(t) time dependent stochastic process of the r.v. l.
The approaches 1) and 2) are able to model the reliability of masonry materials over time and predict, in probabilistic terms, the occurrence time of the expected damage.
The procedures have been applied to full-scale models built in Milan in 1990. To measure the masonry decay in time a non-destructive technique has been adopted and the data collected have been elaborated using the approaches 1) and 2). The results obtained allow the good convergence of both the procedures as well as their different possible applications. On the base of these results a discussion on the possible use of these procedures in the maintenance strategies planning is introduced
Effectiveness of a dehumidifying render system in tackling rising damp: Laboratory, small scale and field tests
No full textIn this research, a commercial 2-layers render system, proposed by the producer for the de-humidification of walls affected by rising damp and salts, has been studied. The research aimed at understanding the moisture and salt transport behaviour of the render system, assessing its ability to favour drying of the wall in comparison to traditional renders, and evaluating it durability in the presence of moisture and salts. Both layers of the render have been characterized in laboratory: composition porosity, pore size distribution, water absorption by capillary and drying behaviour have been measured. The performance of the render system in the presence of moisture and salts has been experimentally evaluated in small scale models and in a field test; this has been done by assessing the moisture and salt content in the render and in the masonry substrate, at different times after the application of the render. Both layers were found to easily transport water and salts, thanks to their high porosity. In the small scale models, the accumulation of salts in the render resulted into efflorescence and moisture spots at the surface due to the hygroscopic behaviour of the salt. No reduction of the moisture content in the walls affected by rising damp was measured after the application of the render. When applied in the field test, the render system did not result in a reduction of the moisture content in the wall in comparison to the previously existing cement-based render
Un approccio probabilistico alla modellazione del processo di degrado nel tempo di murature soggette ad ambiente aggressivo
No full textSalt weathering: advancements in experimental research on assessment and forecasting
No full textSalt weathering is one of the most recurrent damage processes affecting both the natural and the built environment. Due to the complexity of the process, numerical models are rarely applied in practice; accelerated weathering tests in laboratory are still the most common way to assess and forecast durability of (conservation and renovation) building materials.....Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Heritage & Architectur
Vochtschade na brand: De casus van de Elleboogkerk in Amersfoort
No full textHet blussen van een brand gaat gepaard met een grote hoeveelheid water die in het metselwerk van een gebouw binnendringt; daarnaast duurt het vaak ook nog lange tijd voor een gebouw weer waterdicht kan worden gemaakt. Dit kan een hoog vochtgehalte in de muren veroorzaken, met alle daaraan verbonden problemen, zoals zouttransport, zout- en vorstschade en biologische groei. In dit artikel wordt de casus van de Neo-classicistische Elleboogkerk te Amersfoort besproken, waarvan de kapconstructie in 2007 door een brand werd verwoest. Naast directe schade door de brand aan het gebouw en de daarin aanwezige museale collectie, ontstond er ook vervolgschade als gevolg van vocht. Onderzoek toonde aan dat een hoog vochtgehalte in de muren, in de nasleep van de brand, de oorzaak is geweest van het loskomen van het nieuwe pleisterwerk, binnen enkele weken nadat dit was aangebracht. Daarnaast maakte het onderzoek het mogelijk om, op basis van het gemeten zoutgehalte in de muur, het risico voor het verder ontstaan van schade in te schatten en advies te geven over het wel of niet vervangen van de (nog) niet beschadigde delen van het renovatiepleisterwerk.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Heritage & ArchitectureHeritage & Technolog
Salt resistant mortars: Present knowledge and future perspectives
No full textSalt crystallization damage is one of the most common causes of decay for bedding, pointing and plastering mortar. Attempts to tackle the problem have been mainly focused on increasing the mechanical strength of the mortar, by the replacement of lime with (PTL) cement, or on reducing the moisture transport capacity, by the addition of silicone based water repellents. Both solutions showed to often have a limited durability to salt decay and a low compatibility with historical buildings. Recently research has started to explore new possibilities for improving the durability of mortars to salt damage; these include engineering of the pore size, replacing of silicone based additives with natural organic water repellent substances and mixing-in of salt crystallization inhibitors able to reduce the harmfulness of salt crystallization. Some preliminary studies show that these directions can be promising for obtaining more durable mortars, compatible with historical buildings.Architectural Engineering and TechnologyArchitectur
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
A study on leaching of crystallisation inhibitor in mortars
No full textCrystallisation due to commonly occurring salts like sodium chloride (NaCl) is a known cause of damage in the built environment. Use of crystallisation inhibitors is a potential solution to reduce salt decay in building materials. Researchers have reported lower damage when sodium ferrocyanide (NaFeCN), a known NaCl crystallisation inhibitor, is mixed in fresh mortar. However, the high solubility of NaFeCN in water could make it susceptible to leaching and thus diminish its effect over time.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Heritage & ArchitectureMaterials and Environmen
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