Compression Behavior of Foundry Sands

Beneficial use and recycling of industrial byproducts promotes sustainability in roadway construction. An estimated 15 million tons of waste sands are produced from foundry operations (e.g., casting) in the US annually, out of which less than 28% is recycled and the remainder is landfilled. High-volume structural fill applications such as highway embankments can possibly use the majority of the foundry sands. One of the primary impediments to beneficial reuse of foundry sand in large volumes, however, is uncertainty with respect to its material and engineering properties, including compressibility and volume change. Foundry sand with bentonite binder may exhibit excessive permanent deformations under long-term loading. Compressibility of foundry sands from five different sources in Wisconsin were evaluated in a systematic suite of one-dimensional (1D) and three-dimensional (3D) compression tests. Compacted foundry sands are more compressible than compacted natural sands. Compressibility of foundry sand increases with bentonite fraction and the rate of secondary compression ratio increases with time. Compressibility parameters for foundry were quantified based on bentonite content. Recommended parameters can be used in numerical analyses to estimate creep deformations of embankments constructed with foundry sands at different stress levels, bentonite content, and time since construction.