Recycled waste foundry sand as a sustainable subgrade fill and pipe-bedding construction material: Engineering and environmental evaluation

Waste foundry sand (WFS) is the primary by-product of foundries. Due to metals present in WFS and negative public perception, this material is commonly discarded to landfill as a waste material. WFS can however be potentially reused as a construction material in civil engineering infrastructure projects. In order to use WFS in a sustainable manner, the engineering properties of this material needs to be properly evaluated and assessed against local requirements. In this research, geotechnical and environmental tests were undertaken to evaluate the properties and viability of WFS for usage in civil engineering construction projects. In addition, control tests were undertaken on recycled glass (RG), a well-accepted waste material that has been successfully implemented in civil engineering applications, for benchmarking purposes. Geotechnical test results, including determination of maximum dry density (MDD) and optimum moisture content (OMC), California bearing ratio (CBR) and permeability, indicate that WFS can satisfactorily be used as fill material in embankments and in pipe-bedding applications. Comparisons of the environmental test results such as chemical composition and leachate analysis, with the requirements of local authorities indicated no particular hazards in the implementation of this material in applications such as road embankment fills and pipe-bedding. The carbon footprint savings through any potential reuse of WFS/RG was furthermore quantified. (C) 2016 Elsevier Ltd. All rights reserved.