Selection of Cementitious Mixes as a Barrier for Landfill Leachate Containment

Cementitious materials have traditionally not been economically viable for most landfill containment systems. Conventional liners have been made with clay and high-density polyethylene membranes, supporting packed aggregate layers. This paper describes an alternative technology in which low-cost concrete liners may be constructed, making use of materials, which are considered to be wastes by their primary producers. Many materials that have the potential for use either as binder or as aggregate materials for concrete currently form part of the United Kingdom landfill inventory. Although unattractive for use as structural concrete, they offer considerable utility for landfill liner applications. Recent increases in disposal costs including the introduction of the landfill tax have, however, made low cost low strength mixes a financially attractive option as a barrier for landfill leachate containment. In this paper the required properties of cementitious mixes for this purpose are discussed. The results of an extensive investigation into potential mixes using various mineral wastes are presented and the measured properties are compared with those, which are required. All of the mixes, which have been investigated, contain large amounts of secondary materials. If these materials were treated as wastes their disposal costs would be high, so the mixes may be designated "negative cost mixes." The results indicate that some of these mixes are well suited to this application.