Plasticity of Clays (Die Plastizitaet der Tone)

Abstract : The flow limit and plastic limit are the actual plasticity limits of clays. The difference between the data for the flow limit and plastic limit, i.e. the plasticity number, is the best measure of the degree of plasticity. According to the varying level of the plasticity numbers, the clays can be grouped into three or four plasticity classes. At the first plasticity class, the class of the highly plastic clays, the adhesion limit lies between both plasticity limits and thereby divides the plasticity for these clays into a sticking plasticity and a nonsticking plasticity. In the case of slightly plastic clays, for the most part the adhesion limit lies outside the plasticity range. A low position of the adhesion limit complicates the handling of clays both in agriculture and in industry. Through the addition of large amounts of sand or small quantities of organic matter, the relative position of the adhesion limit can be raised.