A confirmatory approach for sustainable utilization of silt fraction from quarry sand mining as flowable fill for backfilling applications
摘要
The depletion of natural river sand has led to a surge in the production of manufactured sand (M-sand) from quarry operations, given its comparable performance as a fine aggregate in concrete construction. However, a considerable fraction of the by-products—particularly fine particles such as dust and slurry—are typically discarded due to their limited ability to enhance concrete strength and workability. This study investigates the potential of utilizing the silt fraction of quarry-derived M-sand, combined with fly ash and cement, as a controlled low-strength material (CLSM). Various mix proportions were tested to evaluate strength and flowability characteristics. An optimized mix with 25% fly ash, 55% water, and less than 10% cement achieved the required flowability (200 mm) and compressive strength (> 0.7 MPa) for use in earth-filling applications. The proposed composition was validated through both pilot-scale field applications and numerical simulations. Ultrasonic Pulse Velocity (UPV) tests showed values ranging from 0.11 to 0.26 km/s—lower than those typical for concrete but sufficient for CLSM performance criteria. Numerical analysis using a simplified plane stress model indicated a maximum vertical deflection of 0.043 × 10–3 m. A life cycle-based carbon footprint assessment estimated emissions at 246.210 kg CO2-equivalent, supporting the material’s environmental viability. These results demonstrate the technical and ecological potential of repurposing M-sand slurry as a sustainable flowable fill in geotechnical applications such as backfilling.
Graphical Abstract