The paper presents the results of an experimental study on the effects of the initial water content and dry density on the soil-water retention curve and the shrinkage behavior of a compacted Lias-clay. The initial conditions after compaction (initial water content and initial dry density) have been chosen on the basis of three Proctor tests of different compaction efforts. According to the eight chosen initial conditions clay samples have been compacted statically. The relation between total suction and water content was determined for the drying path starting from the initial conditions without previous saturation of the specimens. A chilled-mirror dew-point hygrometer was used for the suction measurements. For the investigation of the shrinkage behavior cylindrical specimens were dried to desired water contents step-by-step without previous saturation. The volume of the specimens was measured by means of a caliper. Based on the test results the influence of different initial conditions on the soil suction and the shrinkage behavior is analyzed. The soil-water retention curves obtained in terms of the gravimetric water content are independent of the initial dry density. At water contents above approximately 11-12.5% a strong influence of the compaction water content is observed. At smaller water contents, the soil-water retention curve is independent of the compaction water content. The results of the shrinkage tests show that the influence of the compaction dry density on the shrinkage behavior is negligible. Similar to the drying behavior of saturated samples a primary and a residual drying process could be distinguished. The primary drying process is strongly influenced by the initial water content. In contrast, the rate of the volume change of the residual drying process is unaffected by the initial water content.

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Abstract. The paper presents investigations on the water balance of an earth fill built of organic clay in humid climate. As the organic soil used for the fill contains geogenetically elevated concentrations of arsenic, particular attention is paid on the seepage flow through the fill. The test fill is 5 m high, 30 m long and 25 m wide. The fill consists of the organic clay compacted at water contents wet and dry of Proctor Optimum covered by a drainage mat and a 60 cm thick top layer. For the determination of the water balance extensive measuring systems were installed. The seepage at the bottom measured so far was less than 2 % of the precipitation. The interflow in the drainage mat above the compacted organic clay was of similar magnitude. The estimated evapotranspiration reached approx. 84 % of the precipitation. According to these measurements the percolation is much lower than the percolation of many landfill covers in humid climates.

Fine-grained soils with an in situ water content above the optimum compaction water content show poor suitability for installation and compaction. This paper presents the findings of an experimental study on the improvement of such soils by adding recycled aggregates from demolition waste. The study covers nine different base soils with a wide range of plasticity and addition rates of up to 50 mass% of recycled aggregates with a grain size 0/4 mm. A comparative analysis of the results from the laboratory study focused on the following parameters: improvement effect, compaction characteristics, air void content and bearing capacity. Soil-related patterns in the changes of these parameters were identified. For any fine-grained soil under consideration for this method of soil improvement, the findings presented herein can thus be used as a first indicator of the achievable results.

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