The Effect of Sand Ratio on Suction and Swelling Pressure of Two Bentonite–Sand Mixtures

Abstract

Bentonite–sand mixtures are chosen as potential barrier materials in various waste disposal system. This paper presents the effect of sand ratio on suction and swelling properties of two bentonite–sand mixtures. Constant volume swelling pressure tests on compacted bentonite–sand mixtures specimens and suction measurements on saturated specimens were carried out. The water holding capacity of the monovalent bentonite–sand mixtures were noted to be higher at lower suction range of 3 MPa, whereas at higher suction range the divalent bentonite–sand mixtures having greater water retention capacity. At a given suction, the increase in sand ratio leads to decreasing the water retention capacity of both the bentonite–sand mixtures. At a given sand ratio the swelling pressure exhibited by divalent bentonite–sand mixture was significantly higher as compared to monovalent bentonite–sand mixtures. Further the swelling pressure was noted to be decreased with an increase in sand ratio.