Applicability of the Fall Cone Test for Measuring the Plastic Limit of Cohesive Soils

Abstract

An investigation was made on the applicability of the Fall Cone Test for determining the plastic limit of cohesive soils. The test was carried out by using 2a=60。,Q=ION cone (60°,ION cone) where a and Q are semi-angle of the cone tip and the cone weight, respectively, on 11 cohesive soils. The test results were compared with those obtained previously using 2a=60°,Q= 0.6N cone (60°, 0.6N cone). According to the results, the penetration depths hp read at the Casagrande plastic limit on the logarithmic penetration (h) vs logarithmic water content (w) straight lines became constant and took the mean value of hp= 5.4 mm. The accuracy of the plastic limits determined by using 60。,0.6N cone and 60°, ION cone for those by the Casagrande method was found to be almost same. However, 60°,10N cone should be preferably used rather than 60°, 0. 6N cone in case that the Fall Cone Test was carried out to determine only the plastic limit.