1,721,058 research outputs found
Effect of low dosages of waste GRP dust on fresh and hardened properties of mortars: Part 1
No full textThe viability of improving some durability aspects of mortars through the addition of low dosages of very
fine Glass Reinforced Plastic by-product was investigated. Replacing 5–10% of sand volume with GRP dust
delays the setting time of cement paste, but the delay can be partially recovered by adopting a previously
thermally treated GRP dust. GRP dust increases the workability, autogeneous shrinkage, deformability
and total porosity of mortars, though with a smaller average radius. It significantly reduces the mechanical
performance of mortars when wet curing conditions are adopted. However, the risk of cracking
induced by restrained shrinkage and capillary water absorption is lower in the presence of GRP dust. This
decrease could imply enhanced durability of GRP mortars when used as supporting role
Cementitious Materials with low additions of waste GRP dust: effect on fresh and hardened properties
No full textThe viability of improving some durability aspects of cementitious materials through the
addition of low dosages of very fine Glass Reinforced Plastic by-product is investigated.
Replacing up to10% of sand volume with GRP dust delays the setting time of cement paste,
but the delay can be partially recovered by adopting a previously thermal treated GRP dust.
GRP dust increases workability deformability and total porosity, though with a smaller
average radius, of cementitious materials and it significantly reduces the mechanical
performance, when wet curing conditions are adopted. The risk of cracking induced by
restrained shrinkage, capillary water absorption and resistance to efflorescence are better with
waste GRP dust addition, especially when combined with silane. This decrease could involve
enhanced durability of GRP mortars when used as supporting role
Use of GRP industrial by-product in cementitious materials
No full textComunicazione a invito al Surendra P. Shah Symposium "Advances in structural concrete
Nanomaterials advancements: probing environmental sustainability of alumina nanofiber dispersion for Ultra High Performance Concrete
Get PDFAlumina nano-fibres, incorporated into Ultra High Performance Concrete (UHPC), play a dual role by enhancing mechanical performance and improving durability under aggressive conditions, particularly through stimulated autogenous crack sealing and performance self-healing mechanisms. The superior performance of UHPC, enriched with alumina nano-fibres, is attributed to their nano-scale reinforcing effects, exerting control over the cracking process from its initiation, and their hydrophilic nature, promoting cement and binder hydration reactions. Goal of this study is to address the environmental sustainability of alumina nanofibres through a Life Cycle Assessment (LCA) analysis. Concentrated versions of alumina nanofibers are specifically examined, employing chemical admixtures such as polycarboxylate sodium salt (PCE) for dispersion. This strategic approach intensifies intermixing and prevents gelatinization arising from the inherent hydrophilic nature of alumina nano-fibres. Through LCA analysis, the study sheds light on the environmental footprint associated with the production and application of alumina nano-fibres in UHPC, through a broad perspective contributing valuable insights into the sustainability of these materials and enabling informed decision-making for their future applications in the construction industry
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Fiber Reinforced Self-Compacting Concrete (FR-SCC): a state of the art perspective
No full textFiber Reinforced Self-Compacting Concrete (FR-SCC) combines the benefits of highly flowable concrete in the
fresh state with the enhanced performance in the hardened state in terms of crack control and fracture toughness
provided by the wirelike fiber reinforcement. Thanks to the suitably adapted rheology of the concrete matrix, it is
possible to achieve a uniform dispersion of fibers, which is of the foremost importance for a reliable performance of
structural elements. Balanced viscosity of concrete may also be helpful to drive the fibers along the concrete flow
direction. An ad-hoc designed casting process may hence lead to an orientation of the fibers “tailored” to the
intended application, which is along the anticipated directions of the principal tensile stressed within the structural
element when in service. This converges towards a “holistic” approach to the design of structure made with highly
flowable/self compacting Fiber Reinforced Concrete (FRC), which encompasses the influence of fresh state
performance and casting process on fiber dispersion and orientation an the related outcomes in terms of hardened
state properties.
The influence of the flow-driven fiber dispersion and orientation on the mechanical performance represents a key
distinctive feature of self-consolidating FRC as compared to traditional vibrated FRC, which cannot be disregarded
when analyzing engineering and mechanical properties of the material. A thorough understanding is required of the
mechanisms underlying the connection between mix-design and fresh state performance, on one hand, and the
dispersion and orientation of the fibers on the other hand, also in the context with monitoring and prediction to
achieve the anticipated performance in the hardened state.
In this framework, this paper will provide a review, based on the author’s own research as well as on a broad
literature survey, of the aforementioned topics and of their influence on the engineering and mechanical properties
of FR-SCC in order to address its use for high end structural applications, among which some distinctive case
studies will be also presented
Variations on the Author
Get PDF“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
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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