Utilization of waste foundry sand (WFS) as impermeable layer (drainage blanket) for pavement structures

Pavement structures are susceptible to water and always been a major concern of pavement engineers. Water may enter the pavement structure from high water table and reduce the strength of granular pavement layers, causing pumping of structure under wheel loadings, resulting diminished pavement support. In this study waste foundry sand is considered as impermeable layer to prevent water penetration. Waste foundry sand samples were collected from different foundries operating in and around Istanbul. Index properties were determined. Optimum moisture contents and corresponding maximum dry densities of samples then obtained applying standard compaction effort. Hydraulic conductivity of samples prepared at maximum dry unit weight and optimum water content were then determined. The effects of compaction energy and bentonite content on the hydraulic conductivity were also investigated. The hydraulic conductivity values determined were in the range between 1 × 10^-5 m/s and 1 × 10^-7 m/s for bentonite content higher than 5%. According to the results obtained, the material may be used as drainage blanket.