New approach for determining the coefficient of consolidation, Cv, for normally consolidated kaolinite clay

Abstract

in this study, the coefficient of consolidation of kaolinite clay is determined using a newly developed test system. The results of these experiments are compared with results obtained from the conventional oedometer test apparatus, Newly developed test system gives the opportunity to apply loads onto the sample easily. Experiments are conducted using normally consolidated kaolinite clay samples prepared in the laboratory, Slurry form of kaolinite clay is preconsolidated using newly designed one-dimensional consolidation (preconsolidation) equipment in order to obtain normally consolidated samples. The newly designed one-dimensional consolidation equipment is made up of translucent plastic tubes, Normally consolidated samples are obtained at different loading conditions of 30 kPa, 60 kPa, 100 kPa, 120 kPa. Then, preconsolidated kaolinite samples are placed into the newly developed test equipment and water pressures of 25 kPa, 50 kPa, 100 kPa, 200 kPa and 400 kPa are applied. Pore pressure values are obtained with certain time intervals using the data acquisition system during the application of water pressure. At the same time, normally consolidated samples are placed into the conventional consolidation test apparatus which also consists of a linear displacement transducer (LVDT) and the data acquisition system. Pore pressure data with respect to square-roof-of-time and logarithm-of-time are plotted. it is clear that there is a similarity between graphs obtained from the newly developed test and the consolidation test. It is found that there is a constant between the coefficient of consolidation obtained from the newly developed test and the coefficient of consolidation obtained from the consolidation test, This constant ranges between 0.50x10(-2) and 2x10(-2) for Casagrande's method and between 0.40x10(-2) and 1.45x10(-2) for Taylor's method.