Volume 33, Issue 1 (January 2010)
Determination of Plastic and Liquid Limits Using the Reverse Extrusion Technique
Consistency limits are fundamental properties of fine grained soils. The techniques used today to determine these parameters are operator dependent; their repeatability is low. In order to overcome and/or reduce those factors affecting the results of conventional testing methods, the reverse extrusion technique was evaluated. Thirty-one inorganic soil samples were used in the experiments. In order to produce a reliable basis for the plastic and liquid limits, a relatively broad database was constituted using the conventional consistency limit tests. Extrusion pressures were then obtained and plotted for different water contents for each sample. A linear relationship was observed among the water content and the logarithm of the extrusion pressure. The extrusion pressures corresponding to the average plastic and liquid limits of the conventional method show a normal distribution about certain values. A more reliable, economical, and robust device with greater repeatability is proposed. The presented approach shows promise in providing a better index parameter to characterize fine grained soils.