Comparison of natural, polymer treated, and sodium activated Ca-bentonites

The hydraulic conductivity of geosynthetic clay liners (GCLs) for the confinement of waste disposal facilities depends on the hydraulic conductivity of the bentonite clay encased between the two geotextiles. Sodium bentonites are widely used for GCLs due to their low hydraulic conductivity to water. Although, calcium bentonites (Ca-bentonites) are low cost and readily available, the hydraulic conductivity of calcium bentonites is higher compared to that of sodium bentonites (Na-bentonites). This study compares the impact of the treatment of Ca-bentonite with an anionic polymer, sodium carboxymethyl cellulose (Na-CMC) using HYPER clay technology, relative to standard sodium activation treatment. The swelling ability and hydraulic conductivity to CaCl2 solutions of a natural (untreated) Ca-bentonite was compared to those of sodium activated bentonite and to polymer treated bentonite. Test results showed the superior performance of the polymer treatment compared to sodium activation

LEARNER INTERACTIONS AND BEHAVIORAL PATTERNS IN ENTERPRISE MOOCS

18th International Conference on Cognition and Exploratory Learning in Digital Age, CELDA 2021 -- 13 October 2021 through 15 October 2021 -- -- 174791This short paper investigates learner behavior in Enterprise MOOCs with the help of interaction patterns. By means of lag sequential analysis, data from 13 openSAP MOOCs from the topic areas business, design, and technology with a total number of N=72,668 active learners have been analyzed. Starting from consistent high-level behavioral patterns, a deeper analysis on the interaction level revealed variations between the course topic areas: Behavioral patterns in technology courses differ from business and design courses. Drawing upon these results, implications for future research are mapped out. © 2021 Virtual Simulation Innovation Workshop, SIW 2021. All rights reserved

Oberflaechenabdichtungssysteme fuer Deponien und Altlasten

Die primaere Aufgabe der Oberflaechenabdeckung ist in der Verhinderung der Zusickerung von Niederschlagswasser zum Muellkoerper zu sehen. Sie hat daher vorwiegend abdichtende Funktionen zu erfuellen. Oberhalb der Dichtungsschicht ist ein Entwaesserungssystem integriert, im Falle von Siedlungsabfalldeponien mit hoeherem Gasanfall wird entstehendes Deponiegas durch eine Gasdrainageschicht abgeleitet. Die oberste Lage des Systems dient als Rekultivierungshorizont der Besiedelung durch Pflanzen. Zusammengefasst sind dies die Funktionen des Oberflaechenabdichtungssystems: - Abdichtung gegenueber Niederschlagswasser; - Abfuehrung von Deponiegas und -sickerwasser; -Pflanzenstandort. (orig./EF)The primary task of surface lining is to prevent rainwater from seeping into the wastes deposited below the surface. Its function is therefore to seal the surface. Above the sealing layer there is a drainage system; if large amount of gas are generated (domestic wastes) the gas is channeled through a gas drainage layer. The top layer of the system serves as recultivation horizon for plants. The functions of the liner are: - sealing against precipitating water; -channeling off gas or - seepage water; - plant site. (orig./EF)SIGLEAvailable from TIB Hannover: RO 6603(34) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman