A new method to classify plastic soils is formulated using the slope of the line defined by its remoulded shear strength (RSu) and water content (w) in log-log, as well as the water content of soil at fluid state. Conventional plasticity values were correlated with the absolute value of the slope of the line, m. The location of the line in log-log space was found to be controlled by the amount of non-plastic fines as well as by the water content at which soil just behaves as a fluid. Shear strength at this condition was arbitrarily taken as 1.5 kN/m~2 and a good correlation was found between this water content and the conventional Liquid Limit (LL). It was demonstrated that for a given value of the LL the absolute value of, m, increases rapidly as the Plasticity Index (PI) decreases, whereas, for a given PI the absolute value of, m, increases slowly as the LL increases. Consequently, it was possible to generate curves in the Plasticity Chart (PC) which represent the locus of soils with identical value of, m. Soil classification is achieved using the correlation of LL with water content at 1.5 kN/m~2 and the absolute value of, m, within the PC. As a result, soil classification obtained with this method is equivalent to that obtained with conventional ASTM methods. Finally, it was found that as values of slope, m, depend on non-plastic fuies content it can be used to define the liquefaction potential of plastic soils.
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