Investigation of the Performance of Small Scale Deep Mixing Columns in Which Silica Fume Is Used as an Additive Using the Tri-Axial Test

Abstract

In this study the effects of silica fumes on the strength of small scale deep mixing columns is investigated using the tri-axial test. Small scale samples were made by mixing clay, cement (CEM I 42.5 R), BASF MasterRheobuild 1000 plasticizer and silica fume. A range of Water/Cement ratio (W/C) of 0.9 – 2.5 was chosen based on preliminary rheological tests. The water content of the clay soil being stabilized was set to a range of 25-33%. The silica fumes content was set to a range of 0 to 15% of the dry weight of the clay. The plasticizer content was set to range between 0 and 5%, while the cement content was determined to range from 5 to 20%. These ranges were selected based on previous studies. The ranges were later on introduced into the Design Expert software which uses the Response Surface Method to provide a list of 21 different designs which were used for preparing samples. The designs were individually prepared and filled in PVC molds of 5cm diameter and 10 cm height and left to cure for 7 and 28 days.