1,720,957 research outputs found
Mechanical performance and medium-term degradation of rubberised concrete
No full textThis laboratory study deals with a comprehensive investigation of modified concrete specimens using rubber particles obtained from End of Life Tyres (ELT). Different types of mixes have been studied with different percentages of rubber particles used as a partial substitute for natural aggregates by using and comparing mixtures with various types of addition and surface treatment. Three types of rubber particles (ash rubber, crumb rubber and tyre chips) have been employed in the rubberised concrete mixtures replacing partially the natural aggregates. Test results shown that the rubberised concrete mix had some appealing characteristics such as a low mass density but worse compressive strength in line with previous studies. Among the most important findings, a decline in mechanical performance was observed in rubberised concrete specimens at an age of about 60 days. Moreover, cracking and delamination phenomena occurred on the test specimens cured under moist conditions which have never been described in the literature so far. The main innovation is in description of these results regarding time-dependent degradation of rubberised concrete and in a preliminary investigation about the causes of this phenomenon
Experimental investigation on degradation processes in concrete with recycled-tire rubber aggregates
No full textExperimental investigation on degradation processes in concrete with recycled-tire rubber aggregates
No full textThis laboratory study deals with a comprehensive and extensive investigation on modified concrete specimens using rubber particles obtained from waste tires. Different types of mix have been studied with different percentage of rubber particles used as a partial or total substitute to natural aggregates by using and comparing mixtures with various additions and surface treatments. Test results show that the rubcrete mix has some appealing characteristics such as a low specific weight but worsen compressive strength in line with previous studies. However, the most important findings of this research also reveal that a decline of mechanical performance have been observed in the rubcrete samples at 60 days. Also cracking and delaminations phenomena occured on the test specimens. This paper presents some of these new results and start investigating the causes of the observed time-dependent degradation
Study of the mechanical behavior of Concrete Structural elements varying the Portland Cement-CSA Ratio Used
No full textCalcium sulphoaluminate (CSA) cement became progressively more used in recent years, considering both the mechanical per-formance and the environmental aspects linked to the CO2 manufacturing emissions lower than ordinary Portland cement (OPC). In this study, the mechanical behavior of steel-reinforced concrete beams made using various binders, such as pure CSA or blends with OPC was investigated experimentally, in terms of flexural resistance, crack pattern (number, length and crack width). For this purpose, a mechanical characterization of the various concrete mixtures at early and later ages was performed. Moreover, an ad-hoc experimental set-up was designed in order to study the durability of structural beams for different concrete types, under specif-ic environmental and service conditions. The results showed a satisfactory behavior of the CSA mixtures when compared with the OPC reference mixture in terms of early age resistance, mechanical performance and crack evolution during the time
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
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
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