Proportioning Spent Casting Sand in Controlled-Low Strength Materials

This research evaluated the potential of spent foundry or casting sand as a constituent controlled low-strength material (CLSM). The physical characteristics of spent casting sand or foundry sand are similar to those of fine aggregate used in high quality CLSM. This study developed different mix proportions for CLSM containing spent casting sand that had strengths between 300 kPa and 800 kPa at 7 days and sufficient flowing characteristics to be self-compacting and self-leveling. Each mix was tested for strength, water demand, rate of strength development, and fluidity. The results show that the spent casting sands provide high-quality material for CLSM. The spent chemically bonded casting sands are excellent replacements for portions of the fine aggregate, while clay-bonded casting sands must be more carefully proportioned and tested to prevent fluidity problems.