Using the BS cone penetrometer for the determination of the plastic limit of soils

The use of the BS cone penetrometer test for the determination of the plastic limit of soils based on the relationship between water content and undrained shear strength is described. The experimental results indicate that the assumptions used which are based on the results of Skempton and & Northey (1953) and the suggestions by Wroth and Wood (1978) agree closely with the experimental results. By performing cone penetration tests with a range of penetration values from about 5 mm to 25 mm, the w-d (water content/penetration) plot can be constructed. The plot on a semi-logarithmic graph will produce two straight lines intersecting at a point with d about 14 mm. From the lower line of the w-d plot, the water content corresponding to a penetration value of 2 mm (i.e. the plastic limit) can be ascertained.