Based on index properties in laboratory testing, foundry sand, and blast furnace steel slag may be considered as a construction backfill alternative. Naturally available granular materials for various fill applications are fast dwindling and sometimes not readily available near every construction site. In the current scenario, there is a substantial need to use alternative geomaterials. Many industry by-products and waste materials [fly ash, copper slag, bottom ash, construction, and demolition wastes (C&D), etc.] have been extensively studied for their suitability as a geomaterial. Steel slag generation in the world was estimated to be in the range of 170-250 MT in 2015, and considerable amounts of waste foundry sand are also generated. In the present study, waste foundry sand from Ordnance Factory, Medak, India, and blast furnace (BF) steel slag from Tata Steel, Jamshedpur, India, are tested for basic characteristics including gradation, specific gravity, morphology, chemical composition, and compaction. The engineering properties, shear strength, and permeability, are evaluated. In addition, leachate studies are conducted to assess the environmental impact of use of these materials for the proposed applications. Compaction behaviour of both the materials is found to be similar to granular soils. Foundry sand and BF steel slag exhibited an angle of shearing resistance of 310 and 370, respectively. A comparative study on the properties of foundry sand and BF steel slag with the conventional fill material is performed, and the two waste products considered in the study are assessed for fill applications. © 2019 American Society of Civil Engineers.