Consolidation Characteristics of Sand–Bentonite Mixtures and the Influence of Sand Particle Size

Abstract

Hydromechanical characteristics of sand–bentonite mixtures, which are generally used as geotechnical barriers, are a well-documented research interest. Because bentonite is a relatively costly material, most of the research has been focused on the influence of bentonite on the various engineering characteristics of sand–bentonite mixtures. Most studies have indicated that sand is the major component in these mixtures. While guidelines regarding the design of sand to be used in a sand–bentonite mixture are not readily available, does sand particle size really influence the engineering behavior of a sand–bentonite mixture and, if it does, to what extent is it still a matter of ambiguity? The current study is an attempt to understand the influence of sand particle size on the consolidation characteristics of sand–bentonite mixtures. Fine sand–bentonite and medium sand–bentonite mixes were prepared with sand content ranging from 5 to 9% by dry weight and tested for consolidation characteristics. The results showed that sand particle size has a significance influence on the consolidation behavior of sand–bentonite mixtures. A comparison between the two sand types for any mixtures showed that the mixture with medium sand possessed a higher coefficient of volume change, a lower coefficient of consolidation, and the lowest time to complete 9% of consolidation (t9) at any given pressure and proportion of bentonite. In addition to the sand particle size, the proportion and swelling tendency of the bentonite also exhibited a major influence on the consolidation behavior.