Abstract
In this study, the power coefficient of one-point liquid limit equation given by ASTM 4318-17 is evaluated for weathered volcanic deposits of Northern Turkey. Total of 35 soil samples taken from depths ranging from 0.2 m to 4 m from 8 different sites in the city of Rize and one site in Trabzon, Turkey are used, and a total of 77 Atterberg limit tests are conducted. Three different sample preparation methods are used: (1) starting from in-situ moisture content without any drying, (2) drying at 60°C oven, (3) drying at 110°C oven. For liquid limit determination by one-point method, the best fitting power coefficient is evaluated for different sample preparation conditions separately, and are compared with the power coefficient suggested by ASTM D4318-17. Soils used in this study are in ML-OL to MH-OH zones in plasticity chart and the liquid limit values vary in the range of 35% to 103% (moist preparation). Liquid limits obtained by multi-point method and the ones obtained by one-point method are found to be similar to each other. It is concluded that although the power coefficient changes (in the range of 0.106 to 0.133 with an average value of 0.120) due to sample preparation technique, they are close to ASTM-suggested power value of 0.121, and the differences in resulting liquid limits are negligibly small (0-2%).