Chemical and geotechnical proprieties of ash-slag mixture from Skawina power plant tested in a model study of earthen dam

Basic chemical and geotechnical properties of an ash-slag mixture from Skawina Power Plant were tested in a dam model, which was built in a medium-sized apparatus for testing the filtration through the embankment models. Piezometers in the apparatus allowed taking samples of the upper water, lower water and water filtrating throughout the dam. Tap water was used in the experiment model, which due to the localization was Krakow city water. Chemical properties were examined for water samples taken after a day and twenty five days of the experiment. From geotechnical properties following were tested: grain size distribution, uniformity coefficient, natural moisture content, wet bulk density, dry density of solid particles, optimum moisture content, maximum dry density of solid particles and permeability coefficient. Soils were classified according to the following standards: PN-B-02481:1998 and PKN-CEN ISO/TS 17892-4:2009. Additionally filtration curve was drawn. Embankment material, due to its geotechnical parameters, very easily succumbed to a suffusion phenomenon. Measured volumetric flows were in the range of 1700–2500 cm3 · hour–1. After a day and again after twenty five days following chemical prosperities of each water (upper, lower, filtrating throughout the embankment material) were tested: conductance, reaction, metal contents (Cd, Cr, Cu, Pb, Ca, K, Mg, Na). Leaching conditions in the experiment were different from those assumed in a standard [Rozporządzenie...1999], however they were much closer to the ones on the borderline of ecosystem and water construction. It was stated that the tested ash-slag mixture has an influence on the tap water used in experiment, particularly in case of reaction, conductance and metals contents (mainly Na, K, Ca and Mg). Determined sodium, potassium, calcium and manganese contents were higher than allowed in standards for surface and ground water [Rozporządzenie... 2011, Rozporządzenie... 2008]. Cadmium, chromium and lead contents were in narrow ranges (Cd and Cr) often below the spectrophotometer determination level. In all cases determined contents were lower than permissible levels for surface and ground water. Additionally, requirements for substances, which are allowed to be put in water or ground were fulfilled [Rozporządzenie... 2011, Rozporządzenie... 2008, Rozpozrądzenie... 2006]. Slowa kluczowe: mieszanina popiolowo-zuzlowa, zapora, wlaściwości geotechniczne, wlaściwości chemiczne