A multi-laminate constitutive model for soft soils incorporating structural anisotropy is presented. Stress induced anisotropy of strength, which is present in multi-laminate type constitutive models, is augmented by directionally distributed overconsolidation. The model is presented in theelastic-plastic version in order to simulate strength anisotropy of soft clayey soils and destructuration effects. Performance of the model is shown for some element tests and for the numericalsimulation of a trial road embankment constructed on soft clays at Haarajoki, Finland. The numerical calculations are completed with the commercial finite element code capable to performcoupled static/consolidation analysis of soils. Problems related to the initiation of in situ stress state, conditions of preconsolidation, as well as difficulties linked to estimation of the model parametersare discussed. Despite simple assumptions concerning field conditions and non-viscous formulationof the constitutive model, the obtained final results are of a sufficient accuracy for geotechnical practice.

The Jurassic kaolinite-illite clays in Rozwady (Opoczno region) were exploited for the needs of the chamotte fireclay refractories plant in Opoczno built in the years 1926–1928. Until the World War II, these clays were a major component of ceramic sets used for manufacturing quartz-chamotte refractories applicable to steel-making ladles in the Upper Silesian steel works. In the year 1990, due to a drastically low demand for chamotte refractories in Poland, both the plant in Opoczno and the Mroczków-Rozwady clay underground mine were shut down. However, recent years have brought about a renewed interest in exploiting the Opoczno clays for the domestic ceramic industry. Clay mining was initiated in 2014 in the new open pit in Borkowice and has also continued as of 2017 exploiting the Rozwady I deposit. In the clay raw material of Rozwady, kaolinite clearly predominates over illite, among the non-clay minerals quartz occurs in variable quantities, whereas the organic matter is a permanent but minor component. The quantity of the organic matter varies within the deposit and forms the basis to distinguish light and dark colored clays. Considering the petrographical reasons, the raw material of Rozwady represents rocks intermediate between claystones and mudstones. The Rozwady clays have been used by many plants producing tiles within the Opoczno region and it is predicted that their use will increase, as the prices of the clay raw materials imported from Ukraine is constantly growing and the cost of their transport is substantial.

The exploitation and processing of lignite in the Bełchatów region is connected with the formation of various mineral waste materials: varied in origin, mineral and chemical composition and raw material properties of the accompanying minerals, ashes and slags from lignite combustion and reagipsum from wet flue gas desulphurisation installations. This paper presents the results of laboratory tests whose main purpose was to obtain data referring to the potential use of fly ashes generated in the Bełchatów Power Plant and selected accompanying minerals exploited in the Bełchatów Mine in the form of self-solidification mixtures. The beidellite clays were considered as the most predisposed for use from the accompanying minerals , due to pozzolanic and sorption properties and swelling capacity. Despite the expected beneficial effects of clay minerals from the smectite group on the self-settling process as well as the stability of such blends after solidification, the results of physical-mechanical tests (compressive strength and water repellence) were unsatisfactory. It was necessary to use Ca (OH)2, obtained from the lacustrine chalk as an activator of the self-settling process It was necessary to use lacustrine chalk as an activator of the self-solidification process. The presence of calcium will allow the formation of cement phases which will be able to strongly bond the skeletal grains. Also, the addition of reagipsum to the composition of the mixture would contribute to the improvement of the physico-mechanical parameters. The elevated SO4 2– ion in the mixture during the solidification allows for the crystallization of the sulphate phases in the pore space to form bridges between the ash and clay minerals. The use of mixtures in land reclamation unfavourably transformed by opencast mining in the Bełchatów region would result in measurable ecological and economic benefits and would largely solve the problem of waste disposal from the from the operation and processing of lignite energy.

Bentonites and clays are included in the group of drilling fluids materials. The raw materials are mainly clay minerals, which are divided into several groups, like montmorillonite, kaolinite, illite, biotite, muscovite, nontronite, anorthoclase, microcline, sanidine or rutile, differing in chemical composition and crystal lattice structure. Clay minerals have a layered structure forming sheet units. The layers merge into sheets that build up to form the structure of the mineral.

The aim of the studies carried out in the ŁUKASIEWICZ Research Network - Foundry Research Institute is to explore the possibility of using minerals coming from Polish deposits.

The article outlines the basic properties of hybrid bentonites, which are a mixture of bentonite clay called beidellite, originating from overburden deposits of the Turoszów Mine, and foundry bentonite from one of the Slovak deposits. As part of the physico-chemical tests of minerals, measurements included in the PN-85/H-11003 standard, i.e. montmorillonite content, water content and swelling index, were carried out. Additionally, the loss on ignition and pH chemical reaction were determined. Based on the thermal analysis of raw materials, carried out in the temperature range from 0 to 1000oC, changes occurring in these materials during heating, i.e. thermal stability in contact with liquid metal, were determined.

Examinations of the sand mixture based on pure clay and bentonite and of the sand mixture based on hybrid bentonites enabled tracing changes in permeability, compressive strength and tensile strength in the transformation zone as well as compactability referred to the clay content in sand mixture. Selected technological and strength parameters of synthetic sands are crucial for the foundry, because they significantly affect the quality of the finished casting.

Based on the analysis of the results, the optimal composition of hybrid bentonite was selected.

This paper presents the qualitative and quantitative characteristics of microstructures of Neogene clays from Warsaw, Poland. Scanning Electron Microscope (SEM) studies were used for the microstructural analysis of natural clays and clay pastes. Qualitative microstructural changes were observed: from a honeycomb microstructure for the initial clay paste to a turbulent microstructure for the dried paste. It was also noticed that water loss caused by the increase of the suction pressure had a significant impact on the microstructural transformations. Significant changes in the quantitative values of the pore space parameters were also observed. Increase of suction pressure and water loss caused a decrease in porosity and changes in the values of morphometric parameters, such as pore distribution; for example, a significant increase of the number of pores of 0−10 μm size and changes in the geometric parameters of the pore space were noticed with the increase of suction pressure. The pore space with larger isometric pores was modified into a pore space with the dominance of small anisometric and fissure-like pores. The increased degree of anisotropy from a poorly-oriented to a highly-oriented microstructure was also observed. After rapid shrinkage the reduction in the number of pores, maximum pore diameter, and total pore perimeter was recorded. The process of rapid water loss induced the closure of very small pores. A similar effect was observed during the increase of the suction pressure, where the closure of pore space of the clay pastes was observed very clearly.