Landfill barriers are used to control or prevent both migration of leachate from the landfill waste and the ingress of the surrounding groundwater. A typical barrier system may include a combination of engineered barriers and fluid collection layers. Bentonite-enriched sand is a commonly used barrier material. The addition of relatively small amounts of bentonite (5–15%) can dramatically improve the performance of a granular material, providing both a low permeability and an enhanced mechanical stability. This paper explores the suction and volume change characteristics of a bentonite-enriched sand. In addition to determining the dry density–moisture content relationships for a range of compactive efforts, a series of oedometer tests has been performed and a comprehensive number of suction measurements made. These data have allowed the suction and volume change characteristics to be defined. The results are presented and discussed, allowing a clearer understanding of the long-term behaviour of these materials to be developed.