Swelling pressure, water uptake, and permeability of 70/30 crushed salt/bentonite

Two experiments were conducted on specimens consisting of 70 percent by dry weight crushed salt and 30 percent by dry weight bentonite. The experiments included fifteen tests and were designed to measure the swell pressures induced by the introduction of saturated Brine A, a high magnesium-content brine, and to measure permeability. Specimens of three dry densities were used: 1600 kg·m-3, 1800 kg·m-3, and 2100 kg·m-3. Experiments were conducted in an oedometer which is a stiff pressure vessel designed to maintain specimens at constant volume. Test durations ranged from 3 to 112 days. When specimens were put into contact with brine, their swelling was inhibited by the oedometer, and the pressures that were required to restrict swelling were recorded. Permeability measurements were made on specimens with densities of 1600 kg·m-3 and 1800 kg·M-3 using the constant hydraulic head, steady-state flow method. Flow was neverestablished for the 2100 kg·m-3 specimens. Including recent data, permeability changed approximately two orders of magnitude (from 1 x 10-15m2 to 1 x 10-17m2) as density increased from 1600 kg· m-3 to 1950 kg·m-3. Moisture content and distribution measurements were made on all specimens post-test. On the average, all specimens reached saturation; however, moisture content distributions were nonuniform in many specimens