The function of compacted clay layers used as liner or covers of landfills is directly affected as soon as cracks originate. The objective of the research project is to investigate the formation of cracks due to desiccation of clayey soils. Desiccation takes place by temperature gradients (rotting process or sun rays) or by moisture gradients. In both cases moisture transfer occurs. Therefore, interrelations between moisture transfer under combined moisture and temperature gradients and tensile stresses in relation to temperature and water content have to be investigated. The soil-water characteristics of Kaolinite have been experimentally determined. A laboratory model is presented to determine the water transfer and the transfer coefficients such as the isothermal and thermal diffusivity and the unsaturated hydraulic conductivity. The test results have been approximated using analytical equations. In several figures the relations of the diffusivity parameters depending on the water content are presented. Using a simplified model the moisture transfer is demonstrated.
In all tests a Kaolinite was used. Applying different methods (tensiometer and vaccum desiccator method, see Meißner et al. 2001) the soil water suction has been measured in the range of 0 to ca. 3 and 5 to 7 pF, where pF is the logarithmic scale of the soil water suction given in centimeters of a water column.
In the current paper, the soil-water transfer parameters of a Kaolinite are measured. A laboratory model is presented, experimental methods are described and test results are approximated through analytical equations. One-dimensional moisture transfer from mineral liner is demonstrated using a simplified model. Another main topic of the research project is the experimental determination of tensile strength, tensile stress-strain-curve and tensile strength-volumetric water content-curve of the Kaolinite used, see Meißner et al. (1998; 2001) and Wendling et al. (2000).
