Dilatancy (granular material) dilation. Because of dilatancy, the angle of friction increases as the confinement increases until it reaches a peak value. After the peak strength of the soil is mobilized the angle of friction abruptly decreases. As a result, geotechnical engineering of slopes, footings, tunnels, and piles in such soils have to consider the potential decrease in strength after the soil strength reaches this peak value. Poorly / uniformly graded silt with trace sand to sandy that is non-plastic can be associated with challenges during construction, even when they are hard. These materials often appear to be granular because the silt is
Polish Soil Classification described diagnostic horizons, diagnostic materials and diagnostic properties. Soil forming processes are not a part of classification but the relationship between the processes and their morphological effects was taken into account during creating differentiating criteria of diagnostic horizons, materials and properties. The classification derives much of international systems: USDA soil taxonomy (1999) and World Reference Base for Soil Resources - WRB (2006). Polish soil science intellectual tradition has always maintained a balance between genetical-geographic approach (typical for the Russian scientific school) and substantional-geological-petrographic approach (characteristic for Western Europe). Multilateral look at the soil manifested, in all editions of classification, that