The state of preservation of waterlogged archaeological wood was evaluated on the basis of the maximum moisture content (MMC), the basic density (BD) and the wood substance density (WSD) determined in water and helium. The degree of wood degradation was compared under the criteria: the loss of wood substance (LWS) and the loss of wood substance density (LWSD). Studies were conducted on the wood samples differing in species, degree of degradation, age and place of origin. The physical properties of wood were determined for the material containing mineral compounds and the material without minerals. The properties of the latter, in which the minerals are replaced by water, were calculated from the mass and volume of the wood containing minerals as well as the content and density of the ash obtained after burning the sample. The study revealed the effect of minerals on the tested parameters and wood degradation indices. A strong relationship between BD and MMC was confirmed for both the wood containing minerals and without them, by contrast a substantially weaker correlation between BD and WSD was observed. It was found that the assessment of the state of wood preservation conducted on the basis of LWS and LWSD yielded different results. In addition, it was revealed that both indices of wood degradation might be unreliable. The main drawback of the LWS-based assessment is associated with a wide range of basic density of fresh wood. In turn, the LWSD mainly indicates the changing ratio of the carbohydrates/lignin content, but fails to provide information on the loss of wood substance. This may hinder the comparison of the wood sampled from different sites and subjected to different decay mechanisms. Nevertheless, the WSD-based assessment of the state of preservation of waterlogged archaeological wood might be a valuable complementary method to the BD-and/or MMC-based assessment, which is routinely carried out in many conservation centers.

Microstructural (fabric, forces and composition) changes due to hydrocarbon contamination in a clayey soil (glacial till) were studied using scanning electron microscopy (microfabric analysis), atomic force microscopy (force measurement) and a sedimentation bench test (particle size measurements). Non-polluted and polluted glacial till from NE Poland (in the area of a fuel terminal) were used for the study. Electrostatic repulsive forces in the polluted samples were much lower than in non-polluted samples. In comparison with non-polluted samples, the polluted samples exhibited lower electric charge, attractive forces on approach and strong adhesion on withdrawal. The results of the sedimentation tests indicate that clay particles form larger aggregates and settle out of the suspension rapidly in diesel oil. In non-polluted soil, the fabric is strongly aggregated – dense packing, dominating face-to-face and edge-to-edge types of contacts, clay film tightly adhering to the surface of larger grains and interparticle pores are more common. In polluted soil the clay matrix is less aggregated – loose packing, dominating edge-to-face types of contacts and inter-micro-aggregate pores are more frequent. Substantial differences were observed in the morphometric and geometrical parameters of the pore space. The polluted soil micro-fabric proved to be more isotropic and less oriented than in non-polluted soil. The polluted soil, in which electrostatic forces were suppressed by hydrocarbon interaction, displays more open porosity and larger voids than non-polluted soil, which is characterized by the occurrence of strong electrostatic interaction between the clay particles.

This pa per pres ents the char ac ter is tics of the expansivity and quan ti ta tive pre dic tion of heave of clay soils from Po land based on suc tion test ing. Eleven Neo gene clays and six gla cial tills, dif fer ing in gen e sis and plas tic ity, were ana lysed to identify the ex pan sive po ten tial us ing eight em pir i cal meth ods. The lab o ra tory stud ies in cluded mea sure ments of soil-wa ter charac ter is tic curves and soil in dex prop er ties. Data from wa ter con tent, vol ume and suc tion mea sure ments served to de ter mine the suc tion com pres sion in dex C h and the suc tion-wa ter con tent in dex Dh/Dw of the soils ex am ined. The val ues of these in dices are clearly de pend ent on the clay frac tion con tent in tested soils. Com pared with gla cial tills, Neo gene clays are expected to ex hibit greater changes in vol ume due to changes in soil suc tion. Com par a tive re sults of the eval u a tion of expansivity sug gest that the cho sen clas si fi ca tion meth od ol o gies pro vided con sis tent ex pan sion rat ings for gla cial tills, while the val ues for Neo gene clays vary from low to very high. The low est expansivity classes have been ob tained from eval u a tion based on soil suc tion. The McKeen (1992) method has been adopted for cal cu la tions of the po ten tial field heave of Neo gene clays and gla cial tills. In or der to pro vide a ra tio nal es ti ma tion of ex pan sive soil be hav iour, spe cial ists should take into con sider ation the spe cific site and de sign fea tures.

The paper presents a study on the shrinkage properties of three clay soils from Poland. Shrinkage limit, volumetric shrinkage and relative volumetric shrinkage were determined, tested according to PN-88/B-04481 (1988) and BS1377: Part 2 (1990) and correlated with the index properties of soils. The shrinkage limit was also calculated from Krabbe's (1958) equation. The results showed that shrinkage limit values obtained by the BS method are lower than those obtained using the PN method, but the values calculated from Krabbe's equation differ significantly. While no strong correlation was found between shrinkage limit and index soil parameters, linear relationships were obtained between volumetric shrinkage and initial moisture content, shrinkage range, plasticity index and clay content. Following multivariable regression analysis, the relative volumetric shrinkage was expressed as a function of plasticity index and moisture content. This function can be used to predict volumetric changes of the foundations based on the moisture content and material properties of the soil.

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