Transport Behavior of Colloids through Compacted Bentonite -Study with 3wt%Nacl Solution and Ca-Type Bentonite-

Kurosawa, Susumi; Kuno, Yoshio*; Morooka, Koichi; Ueta, Shinzo*

The transport behavior of colloids through the compacted sand-bentonite mixture was investigated by the column experiments. Colloidal gold was used to simulate the mobile colloids because gold colloid was stabilized easily. The sand-bentonite mixtures were prepared by mixing 30wt.% silica sand with the bentonite (Na-type and Ca-type) and were compacted at the dry density of 1.6g/cm. The colloidal particles in the 3.5% NaCl solution migrated through the compacted sand- Na bentonite mixture at 8kgf/cm of injection pressure. However colloidal migration was not observed after injection pressure of the colloidal solution was lowered below the swelling pressure. And the selective flow path of colloids in the compacted sand-bentonite mixture was observed after the experiment. On the other hand, colloids in the pure water were filtered by the compacted sand- Ca bentonite mixture.