Differentiated grouting reinforcement for mines based on material rheology and coal–rock bonding characteristics

Roof breakage and weak coal seams frequently trigger rib spalling and roof collapse at longwall faces, posing major risks to mine safety. Grouting reinforcement is an effective measure to stabilise fractured coal–rock masses, yet its performance strongly depends on selecting materials that balance structural requirements, construction safety and economic feasibility. This study presents a combined laboratory–field evaluation of four commonly used grouting materials—ordinary Portland cement (PISC), single-component inorganic material (JIRM), two-component inorganic material (TIRM) and two-component organic material (SPM). Their rheological behaviour, reinforcement effects on coal–rock composites and failure characteristics were examined, followed by full-scale verification at an operating longwall face. The results show clear differentiation in material performance: TIRM develops the highest compressive strength and is suited to high-stress reinforcement; SPM exhibits superior macroscopic ductile failure characteristics, enabling rapid stabilisation in emergency conditions; JIRM provides excellent flowability and cost advantages for large-scale pre-grouting; whereas PISC shows comparatively limited applicability. On this basis, a differentiated material selection strategy was formulated and successfully applied in the field, resulting in reduced material consumption, lower operational cost and markedly improved face stability. The study offers a practical framework for matching grouting materials to geological and operational demands, providing guidance for mines with similar working conditions. • Integrated lab–field tests reveal distinct rheology, bonding and strength among four grouts. • A differentiated material-selection strategy was proposed for zone-specific reinforcement. • Three-way ANOVA statistically confirms material, curing and substrate effects on strength. • Material applicability evaluated via rheology, setting behaviour and bonding tests. • Differentiated grouting strategy improved working-face conditions and reduced costs.