1,720,964 research outputs found
Characterization of Water Sensitivity of Asphalt Mixtures with Coaxial Shear Test
No full textThe CoAxial Shear Test (CAST) performs fatigue test under simultaneous action of dynamic loading, temperature cycles and water, and modulus test on wet or dry specimen. Both a dense graded and an open graded mixture were studied at different air void content. The water sensitivity of both mixtures was determined by comparing fatigue performance of dry and wet tests. Additionally, the effects of water action, temperature and loading cycles were also investigated by comparison of modulus test before (undamaged specimen) and after (damaged specimen) each fatigue test. The introduced Water Sensitivity Index for fatigue test confirms that water damage in asphalt pavements is considerably related to air voids. Finally, the modulus test analysis allowed explaining also the different consequences of environmental factors on viscoelastic properties of asphalt mixtures by using the Standard Linear Solid model. © 2008 Lavoisier
Characterization of Water Sensitivity of Asphalt Mixtures with Coaxial Shear Test
No full textThe CoAxial Shear Test (CAST) performs fatigue test under simultaneous action of dynamic loading, temperature cycles and water, and modulus test on wet or dry specimen. Both a dense graded and an open graded mixture were studied at different air void content. The water sensitivity of both mixtures was determined by comparing fatigue performance of dry and wet tests. Additionally, the effects of water action, temperature and loading cycles were also investigated by comparison of modulus test before (undamaged specimen) and after (damaged specimen) each fatigue test. The introduced Water Sensitivity Index for fatigue test confirms that water damage in asphalt pavements is considerably related to air voids. Finally, the modulus test analysis allowed explaining also the different consequences of environmental factors on viscoelastic properties of asphalt mixtures by using the Standard Linear Solid model. © 2008 Lavoisier.The CoAxial Shear Test (CAST) performs fatigue test under simultaneous action of dynamic loading, temperature cycles and water, and modulus test on wet or dry specimen.
Both a dense graded and an open graded mixture were studied at different air void content. The water sensitivity of both mixtures was determined by comparing fatigue performance of dry and wet tests. Additionally, the effects of water action, temperature and loading cycles were also investigated by comparison of modulus test before (undamaged specimen) and after (damaged specimen) each fatigue test.
The introduced Water Sensitivity Index for fatigue test confirms that water damage in asphalt pavements is considerably related to air voids. Finally, the modulus test analysis allowed explaining also the different consequences of environmental factors on viscoelastic properties of asphalt mixtures by using the Standard Linear Solid model
Influence of water and temperature on mechanical properties of selected asphalt pavements
No full textOne of the main causes of distress in asphalt pavements is water damage. The purpose of this paper is to compare different test methods to evaluate moisture susceptibility. This is of special importance because of the insufficient effectiveness of the procedures currently used. In this research experiments were conducted to investigate the effects of water and temperature on mechanical properties of mixtures with different air voids content. The evaluation of such properties concentrates on the following three approaches: innovative (Coaxial Shear Test), traditional (Indirect Tensile Test) and empirical (Cantabro Test). Specimens were prepared by means of Superpave Gyratory Compactor (SGC) and divided in two different subset for controlled dry and wet conditioned testing. Test results indicated that Indirect Tensile Test (IDT) is not able to discriminate between wet and dry condition as the Coaxial Shear Test (CAST) does. The CAST method reproduces closest the real field conditions and indicates clearly the risk of water damage for open graded mixtures (high air voids content). Dense graded mixtures (low air voids content) showed less influence probably due to the reduced amount of penetrating water. Cantabro Tests (CAT) provided also significant results in good correlation with air voids content and material properties of asphalt mixes
Influence of water and temperature on mechanical properties of selected asphalt pavements
No full textLes dégâts causés par l’eau sont une des causes les plus importantes de la dégradation des chaussées. Cet article présente une comparaison de différentes méthodes d’essai utilisées pour évaluer la susceptibilité à l’eau des enrobés bitumineux.
Les effets de l’eau et de la température sur les propriétés mécaniques d’enrobés présentant des teneurs en vides différentes ont été étudiés. L’évaluation de ces propriétés repose sur les trois approches suivantes: innovatrice (essai de cisaillement coaxial), traditionnelle (essai de traction indirecte) et empirique (essai Cantabro). Les éprouvettes ont été confectionnées à l’aide d’un compacteur giratoire superpave et réparties en deux sous-ensembles pour les essais en conditions sèches et en conditions humides.
L’évaluation des résultats montre que l’essai de traction indirecte ne permet pas de différenciation entre les résultats obtenus à l’état sec et l’état humide alors que l’essai de cisaillement coaxial permet de mettre clairement en évidence les dommages causés par l’eau sur les enrobés à haute teneur en vides. Les enrobés à teneur en vides peu élevée présentaient des dommages moins importants ce qui est probablement dû au fait que la quantité d’eau pouvant pénétrer dans les éprouvettes est faible. L’essai de cisaillement coaxial reproduit ainsi très fidèlement les conditions in situ.
L’essai Cantabro fournit lui aussi des résultats significatifs qui sont en étroite corrélation avec la teneur en vide et les propriétés mécaniques des enrobés.One of the main causes of distress in asphalt pavements is water damage. The purpose of this paper is to compare different test methods to evaluate moisture susceptibility. This is of special importance because of the insufficient effectiveness of the test procedures currently used.
In this research, experiments were conducted to investigate the effects of water and temperature on mechanical properties of mixtures with different air void content. The evaluation of such properties concentrates on the following three approaches: innovative (Coaxial Shear Test), traditional (Indirect Tensile Test) and empirical (Cantabro Test). Specimens were prepared by means of Superpave Gyratory Compactor (SGC) and divided in two different subsets for controlled dry and wet conditioned testing.
Test results indicated that the Indirect Tensile Test (IDT) is not able to discriminate between wet and dry condition as the Coaxial Shear Test (CAST) does. The CAST method reproduces closest the real field conditions and indicates clearly the risk of water damage for open graded mixtures (high air void content). Dense graded mixtures (low air void content) showed less influence probably due to the reduced amount of penetrating water.
Cantabro Tests (CAT) provided also significant results in good correlation with air void content and material properties of asphalt mixes
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
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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