Dynamic Properties of Slag Cement Stabilized Kaolinite

Because of its low strength, soft ground is usually improved to increase strength stability and decrease settlement. Grouting is one of the ground improvement method, which adds reinforcing materials into ground. Portland cement is a common material to be used for soft ground improvement. In addition, some additives have been used to replace part of the cement due to their economic and environmental advantages, such as slag and fly ash. In this study, the Kaolinite and slag cement were obtained in dry powder initially. Engineering properties of this clay including specific gravity, liquid limit, and plastic limit were examined first. Afterwards, the clay was mixed with different amount of slag cement and water. The clay water content, ω, is defined as the weight of water in clay to dry weight of kaolinite. The slag-cement content is defined as the dry weight of slag cement to dry weight of kaolinite, which is written as C/S ratio. Three different C/S ratios and three different clay water contents were used. The resonant column tests with three different confining pressures were carried out in this study. The specimen size is 7 cm in diameter and 15 cm in height. All the specimens in this research are tested at curing time of 7, 14, 28, and 56 days. The effect of shear strain, confining pressure, cement content, water content and curing time on shear modulus and damping ratio of stabilized clay were discussed. The range of shear strain is from 10-5 % to 10-2 % with the threshold shear strain ranging from 10-4 % to 10-3 %. The shear modulus increases slightly with increasing confining pressure. However, confining pressure has a little influence on damping ratios. The shear modulus increases with increasing in slag-cement content but decreases with increasing in water content. On the other hand, the effect of slag-cement content and water content on damping ratio is not apparent. After curing, the maximum shear moduli increase and the minimum damping ratios decrease. Thus, the stiffness of stabilized clays enhance. As a result, the slag cement used in this study is an effective material in ground improvement.