Settling of Kaolinite in Different Aqueous Environment |
| |
| Authors: | Abidin Kaya Ali Hakan Ören Yeliz Yükselen |
| |
| Institution: | 1. Department of Transportation , Materials Research Laboratory , Honolulu, Hawaii, USA Abidin_Kaya@urscorp.com;3. Civil Engineering Department , Dokuz Eylul University , Buca, Turkey |
| |
| Abstract: | Settling characteristics of soils carry great importance for geotechnical engineers since sediments properties are formed during the settling of soil particles in an aqueous environment. In this study, settling characteristics of kaolinite are investigated. Different ionic strengths of NaCl, CaCl2 and AlCl3 were considered as a function of pH in aqueous environment of varying solid concentrations. Factors affecting the settling characteristics and fabric of kaolinitic sediments have been identified. The results of the study reveal that kaolinite settles in either flocculated or dispersed forms depending on pH and ion concentration. Flocculated settling occurs in acidic pH due to formation of flocs in edge-to-face structure with increasing positive charges at the particle edges. Dispersed settling occurs in alkaline pHs when ionic strength is low. When ionic strength is increased in alkaline pHs, kaolinite particles settle in flocculated form. Furthermore, the results show that pH has a significant role on the final sediment thickness or void ratio of kaolinite. Densely packed structures in alkaline and loosely packed structures in acidic aqueous environments are formed depending on pH level. Results also show that as the solid concentration increases, the settling rate decreases due to buoyancy effect. Finally, the zeta potential of kaolinite is correlated with the final sediment thickness or void ratio of kaolinite as a function of pH. This correlation proves that there is a good agreement between zeta potential and the final sediment thickness or void ratio, especially when the soil is settled in a dispersed form. |
| |
| Keywords: | dispersed edge-to-face flocculated kaolinite pH sediment thickness settling solid concentration void ratio zeta potential |
|
|
