Weiterentwicklung von Deponieabdichtungssystemen. Teilvorhaben 24: Diffusion von Wasser in wasserteilgesaettigten Boeden und Abdichtungsmaterialien Transportmechanismen und Strukturparameter

The construction of a composite basal landfill liner system, whereby a geomembrane overlies a mineral layer, can lead to desiccation of the miner liner and the impairment of its sealing properties. This process is mainly caused by the temperature gradient which exists across a landfill. This project investigated the process of vapour phase water diffusion in compressed earthen materials, which are used in the construction of landfills. Diffusion coefficients, which are dependent on water content and temperature, were measured. The process of diffusion in miner liner materials with a low water content is determined by water absorption, whereby water transport takes place only by way of surface diffusion. With higher water contents, gas diffusion occurs. Because surface diffusion dominates the transport process, the diffusion coefficient decreases with increasing temperature. The influence of compression on the transport process was also investigated. Compression results in blockages in the pore system being created which lead to an increase in tortuosity. In one clay sample a critical porosity was determined in which the pore system was blocked to such an extent that transport could not take place. Further investigations into the pore system and transport process were undertaken. In addition, the tortuosity in compressed water-saturated soils was determined for comparison of partly water-saturated with water-saturated liner material. (orig.)SIGLEAvailable from TIB Hannover: F95B2436+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman