1,720,980 research outputs found
Preliminary Assessment of Rice Husk Ash (RHA) as Functional Interphase Agent in Sustainable Composite Systems for Structural Strengthening
No full textOver the last few years, the effectiveness of textile-reinforced mortar (TRM) composite systems for structural retrofitting has led to the widespread adoption of these materials in the practice and to the issue of up-to-date design guidelines. Nonetheless, the weak interfacial bonding that is frequently observed between matrix and fibres is likely to cause inconsistent failure modes and, generally speaking, to severely limit the reinforcing potential of the textile. A promising solution to tackle this issue consists in treating the surface of the reinforcing fibres with a functional coating to improve the adhesion at the interphase. In this paper, a pilot study is presented to assess the effectiveness of a fully sustainable polymer coating, consisting in polyvinyl alcohol (PVA) loaded with with rice husk ash (RHA) or with a 50/50 mixture of RHA and silica fume (SF). The coating was applied on basalt fabrics to reinforce TRM coupons that were mechanically tested under uni-axial tensile loads. The mechanical properties of the TRM samples were significantly increased by up to 20%, and the peak load was attained at a higher deformability level, which is a clue of the enhanced ductility of the reinforced elements
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
Analytical Approach for Modelling the Pull-Out Mechanism of Recycled Synthetic Fibres in Fibre-Reinforced Concrete (FRC)
Full text linkThis study presents a simple one-dimensional analytical model describing the pull-out process of an elastic fibre embedded in a cement matrix, which captures the ductile behaviour of Fibre Reinforced Concrete (FRC) elements. The shear stress arising at the frictional interface between fibre and matrix during the pull-out is assumed to increase with the slippage distance, as a consequence of the growing abrasion of the fibre surface. The equilibrium conditions between the external axial load and the interfacial shear stress are imposed with reference to the undeformed configuration. The model is validated through comparison with both experimental data obtained by testing partially recycled polymeric fibres embedded in a cement matrix, and several datasets available in the literature comprising polypropylene fibres with and without silica coatings. The proposed model can properly describe the response of synthetic fibres that exhibit considerable axial elongation and slip-hardening interface behaviour. However, it may also predict the non-linear relation between the tensile load and the fibre displacement for different kinds of fibre, by setting adequately the constitutive parameters
Secondary Raw Materials for Circular Economy in Construction Sector: A Review
No full textConstruction and demolition waste (CDW) is very high in quantity, 30% - 40% of total
solid waste and their management is inadequate and lack the integration of sustainability concepts.
This situation leads to severe environmental effects, which are mainly associated with the
production of new building materials due to the low recovery rate. In fact some studies show that 5-
10% of total energy consumption across the EU is related to the manufacture of construction
products. For this reason, CDW is a priority for many policies globally. For several years, a
growing trend towards more sustainable construction processes has been taking place with a focus
on secondary raw materials with lower environmental impacts on the entire life cycle. For this
reason, this paper intends to contribute to increasing knowledge in this field through a review
article. The review has the aim to evaluate the research gap, strategies to reduce construction waste
and to promote the recycled materials use for a circular economy in construction sector.
The results of the study showed that interest in this field of research has grown strongly over the
years: the most publications on the subject relate to the last five years. On the other hand, issues
relating to the topic did not attract particular interest in the range 2010-2016, in fact the number of
publications in this period did not exceed 4%.
The research showed that Europe is among the communities most sensitive to the issue and it has
clearly revealed that there are still many barriers and research gaps to be overcome on this issue and
the study has tried to identify the main ones
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe 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
Full text linkWe 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
Use of Recycled and Virgin Carbon Fibers in Limestone Calcined Clay Cement Composites
No full textThe urgent need to reduce the environmental impact of building materials has led to the recent development of low-clinker binders, such as limestone calcined clay cement (LC3). The possibility of using LC3 to produce cement-based composites with high mechanical properties and reduced environmental impact is certainly of great interest. In this study, two LC3 mixtures with different mechanical performances (low and high strength) were investigated. Chopped carbon fibers coming from end-of-life prepreg carbon textiles (rCF), recovered through pyrolysis, and virgin carbon fibers (vCF) were used to reinforce the matrices. Different fiber dosages were investigated, up to 1.5% by volume. Fiber reinforced LC3 composites were characterized through compression and bending tests. The addition of both rCF and vCF results in a decrease in matrix workability, by increasing fiber volume. On the other hand, rCF were able to increase both the compression and bending performances of the cementitious composites, up to 66% and 53%, respectively. Remarkably, no significant differences were found in using rCF instead of vCF
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