Influence of superabsorbent polymer (SAP) content, particle size and sodium silicate modulus on the performance of fly ash-slag paste filling materials

Abstract

The use of solid waste cementitious materials in coal mining and mine filling applications has been limited by substantial volume shrinkage and inadequate hydration. This study explored the incorporation of a novel SAP to improve the workability of solid waste filling materials. We examined the impact of SAP content, particle size, and sodium silicate modulus on the workability and mechanical properties through fluidity, setting time, compressive strength, and drying shrinkage tests. The water absorption and release mechanism of the SAP, along with its effects on workability and mechanical properties, were investigated using nuclear magnetic resonance, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Our findings demonstrated that optimizing the SAP content, particle size, and sodium silicate modulus significantly enhanced the workability, stability, pumpability, and compressive strength of fly ash-slag paste filling materials. Our findings offer insights for modifying and developing solid waste filling materials and executing practical mine filling projects.