Abstract
The kinetics of settling particles in clay suspensions was examined and described by using three kinds of forces which are exerted on solids: gravitation, elastic force and viscous types. Then, it was related to the hydraulic flow phenomenon through fine solids system, this relation enabled us to evaluate the hydraulic conductivity of dilute clay suspensions from their settling characteristics.
The measured hydraulic conductivity for dilute bentonite suspensions, whose initial solid ratio ranged from 2.0 to 4.0%, was far greater than 103 of that predicted by the Kozeny-Carman equation. This difference increased to 106-fold, as the initial solid ratio decreased to 2.0%.
To express the failure of the Kozeny-Carman equation in clay suspensions, a “macro pore model” was proposed. This model is based on the assumption that aggregates may form in suspensions and hydraulic flow mainly depends on macro pores, namely, inter-aggregate pores. We formulated the effect of macro pores into Eq.(16), which proved to be effective in explaining deviations from the Kozeny-Carman equation.
