Foundry Green Sands as Hydraulic Barriers: Laboratory Study

Abstract

A laboratory testing program was conducted to assess the use of foundry sands from gray iron foundries, typically called green sands, as hydraulic barrier materials. Foundry green sands are mixtures of fine uniform sand, bentonite, and other additives. Specimens of foundry sand were compacted in the laboratory at a variety of water contents and compactive efforts and then permeated in rigid-wall and flexible-wall permeameters to define relationships between hydraulic conductivity, compaction water content, and dry unit weight. Additional tests were conducted to assess how hydraulic conductivity of compacted foundry sand is affected by environmental stresses such as desiccation, freeze-thaw, and chemical permeation. Results of the tests show that the hydraulic conductivity of foundry sand is sensitive to the same variables that affect hydraulic conductivity of compacted clays (i.e., compaction water content, and compactive effort). However, hydraulic conductivities <10