735 research outputs found
Multiscale Analysis on the Behaviour of a Lime Treated Bentonite
No full textAbstractAn insight into the microstructural evolution of clay-lime-water systems and its influence on the hydro-mechanical behaviour of treated bentonite has been presented. The time-dependent mineralogical and microstructural changes induced by lime addition on a natural bentonite have been investigated in order to provide a better understanding of the kinetic of the ongoing reactions. The effects of lime addition on the clay particle arrangements have been inferred from dynamic light scattering measurements, whereas the mineralogical changes have been monitored at increasing curing time by X-Ray diffraction and thermogravimetric analysis. The bentonite showed a high initial reactivity characterized by a rapid and total consumption of lime, which promoted the formation of new hydrated phases since the very short term (0 days of curing). Oedometer tests on not treated and lime stabilised saturated samples have been performed at increasing curing times. The results showed the combined effect of clay particles arrangement and bonding on the mechanical behaviour of treated samples
Use of Alkali-Activated Fly Ashes for Soil Treatment
No full textThe use of alkali-activated fly ashes (AAFA) to improve engineering properties of clayey soils is a novel solution, alternative to the widely diffused improvement based on the use of traditional binders such as lime and cement. An experimental investigation on chemo-physical evolution of alkali-activated binders and their use for soil improvement has been developed. Treated samples were prepared by mixing soil and fly ash with water and alkaline solution and dynamically compacted. Mechanical behaviour has been investigated by means of triaxial tests performed on treated samples compacted at optimum water content. Addition of alkali activated binder increased stiffness and shear strength of treated samples, whose extent depends on binder content and curing time
Multi-scale analysis on soil improved by alkali activated binders
No full textIn the present paper, the use of alkali activated binders to improve engineering properties of clayey soils is presented as an alternative to traditional binders such as lime or cement. An alkali-activated fly ash and its chemo-physical evolution has been monitored at increasing curing times by means of X-Ray Diffraction and Scanning Electron Microscopy. Alkali-activated binder has been mixed with soil for evaluating the improvement of its mechanical behaviour. One-dimensional compression tests on treated samples have been performed with particular reference to effects induced by binder content and curing time. Test results showed a high initial reactivity of the alkali activated systems promoting formation of new mineralogical phases responsible of the mechanical improvement of the treated soil
Alkaline activation of non-calcined kaolins
No full textDans un contexte de valorisation des ressources naturelles et de mode de construction réduisant l’impact environnemental, l’utilisation de matériaux alcali-activé pourrait être une solution alternative. L'activation alcaline (AA) du kaolin calciné (métakaolin) est bien connue pour produire un liant aux propriétés très intéressantes. Cependant, la calcination du kaolin est coûteuse et énergivore et pourrait ne pas s’avérer nécessaire lorsqu’on cherche à améliorer les propriétés mécaniques de sols par exemple de quelques mégapascals. Ainsi, dans cette thèse, nous avons étudié l’AA de kaolin non calciné par une solution de silicate de sodium enrichie ou non en soude afin d’évaluer le potentiel réactif de ce que pourrait être un sol modèle riche en kaolins. La description réactionnelle s’est principalement basée sur l’utilisation de la DRX et la RMN du solide ( 29 Si et 27 Al). La Kaolinite montre une réactivité qui augmente en présence de soude qui se traduit par la formation de différents gels riches en Si et par la formation de zéolites dont les caractéristiques diffèrent en fonction des concentrations étudiées (Hydroxysodalite, Phillipsite, Zéolite X). Enfin, une modification des conditions de cure a été étudiée. La cure au contact de l’air inhibe la formation de zéolites et favorise la formation d’un gel plus riche en Al. Pour finir les propriétés mécaniques des matériaux sont étudiées. Les résistances mécaniques développées sont faibles et l’incorporation de kaolin activé à un métakaolin réduit fortement la résistance à la compression des matériaux. La formation de zéolites (Chabazite-Na et Phillipsite) est proposée pour expliquer cette baisse des résistances.In a context to valorize natural resources and construction method which reduce environmental impact, the use of alkali-activated materials could be an alternative solution. Alkaline activation (AA) of non-calcined kaolin (metakaolin) is well known to produce a binder with very interesting properties. However, kaolin calcination process is expensive and energy consuming and is not necessary when trying to improve the mechanical properties of soils, for example, by a few megapascals. Thus, we studied the alkaline activation of non-calcined kaolin with a sodium silicate solution enriched or not in soda in order to evaluate the reactive potential of what a model soil rich in kaolins could be. The reaction description was based mainly on XRD and solid-state NMR ( 29 Si and 27 Al). Kaolinite shows an increased reactivity in the presence of soda, which results in the formation of different Si-rich gels and in the formation of zeolites whose characteristics differ according to the concentrations studied (Hydroxysodalite, Phillipsite, Zeolite X). Finally, a modification of the curing conditions was studied. The cure in contact with air inhibits the formation of zeolites and promotes the formation of a gel richer in aluminum. To finish the mechanical properties of materials were studied. The developed mechanical resistances are lowand the incorporation of activated kaolin with a metakaolin greatly reduces the compressive strength of the materials. Zeolites formation (Chabazite-Na and Phillipsite) is proposed to explain this decrease in resistance
Saint Dimitri of Rostov and Dostoevsky
No full textAcademic literature until now has ignored the possibility of seeing the roots of Dostoevsky’s idea of a God-bearing people in the Saint Dimitri of Rostov’s conception of the passion bearer. But, on the contrary, obvious parallels between the two permit the author to speak of a deliberate coincidence. On the other hand, the two are divided in their conceptions of the reasons for human sufferin
Die Herkunft des byzantinischen Familiennamens Λάσκαρις
No full textIn this article, the author suggests a new etymology for the name Laskaris, born by a family that gave Byzantium one of its imperial dynasties. Older hypotheses are examined, especially the generally accepted one according to which Laskaris is a name of Persian origin meaning "warrior." The author suggests Lascaris rather comes from a Arabic word defining a physical feature: "blonde" or "red-haired.REB 62 2004 p. 269-273
Dimitri Theodorides, Die Herkunft des Byzantinischen Familiennamens Αάσκαρις. — Cet article propose une nouvelle étymologie du nom Lascaris, porté par une famille qui donna une dynastie à Byzance. L'auteur reprend les hypothèses proposées, notamment celle qui est généralement admise et qui ferait de Lascaris un nom d'origine perse, signifiant le « guerrier ». L'auteur propose plutôt d'y voir un mot arabe caractérisant un trait physique : le « blond » ou le « roux ».Theodoridis Dimitri. Die Herkunft des byzantinischen Familiennamens Λάσκαρις. In: Revue des études byzantines, tome 62, 2004. pp. 269-273
Influence of Pore Water Chemistry on Hydraulic Conductivity of Kaolinite Suspensions
No full textAbstractThe role of pore water chemistry on particle aggregation and soil formation during sedimentation process has been investigated for a kaolinite clay suspensions. The modification of surfaces charge properties of clay minerals induced by different pore water chemistry rules the particles arrangement. As a consequence, at volume scale the sedimentation behaviour and in turn the physical, mechanical and hydraulic behaviour of the formed soil skeleton are changed. Sedimentation tests on several suspensions showed the influence of different aggregation on settling and self-weight consolidation stages. Hydraulic conductivity of kaolin suspensions has been estimated from the settling velocity recorded in sedimentation tests. Test results showed the relevant dependency of the hydraulic conductivity of the clay suspensions on the particle arrangement induced by the pore water chemistry
Take me to church
No full textThis thesis is a narrative of masculinity and Latinx identity. More specifically, multiple generations of Puerto Ricanness.M.F.A.Includes bibliographical referencesby Dimitri Reye
Book Launch | Dimitri Van Den Meerssche's The World Bank's Lawyers
No full textOn Wednesday 16 November, the ESIL Interest Groups on History of Intentional Law and International Organisations and Völkerrechtsblog, hosted a book launch for The World Bank’s Lawyers by Dr. Dimitri van den Meerssche (Queen Mary University London).In addition to hearing from the author, discussants included Negar Mansouri (Graduate Institute of International and Development Studies), Dr Gail Lythgoe (University of Manchester), Dr. Tommaso Soave (Central European University) and Dr. Ahmed Memon (Cardiff School of Law and Politics). Florenz Volkaert (Ghent University) moderated.<br/
Book Launch | Dimitri Van Den Meerssche's The World Bank's Lawyers
No full textOn Wednesday 16 November, the ESIL Interest Groups on History of Intentional Law and International Organisations and Völkerrechtsblog, hosted a book launch for The World Bank’s Lawyers by Dr. Dimitri van den Meerssche (Queen Mary University London).In addition to hearing from the author, discussants included Negar Mansouri (Graduate Institute of International and Development Studies), Dr Gail Lythgoe (University of Manchester), Dr. Tommaso Soave (Central European University) and Dr. Ahmed Memon (Cardiff School of Law and Politics). Florenz Volkaert (Ghent University) moderated.<br/
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