Experimental study on nano-modified Portland cement-based grouting materials

Wang Gang; Cai Jin

doi:10.16186/j.cnki.1673-9787.2024030080

Abstract：Objectives To address issues in rock mass microfracture grouting for reinforcement and seepage control,this study investigated nano-modified Portland cement-based grouting materials.Methods A nano-modified grouting material was developed using Taguchi-grey correlation optimization combined with or-thogonal tests.Signal-to-noise ratio analysis based on the Taguchi method was applied to systematically evaluate the effects of nano-CaCO3,polycarboxylate superplasticizer,ultrafine fly ash,and water-cement ratio on the grouting material's viscosity,bleeding rate,setting time,and 28 d stone body strength.Re-sults The orthogonal tests showed that the material prepared under the optimal ratio from Taguchi-grey cor-relation optimization exhibited excellent fluidity and mechanical properties,ensuring injectability and rein-forcement performance.Signal-to-noise ratio analysis indicated:nano-CaCO3 significantly increased viscos-ity while reducing bleeding rate;28 d stone strength first increased and then decreased with increasing nano-CaCO3 content.Polycarboxylate superplasticizer reduced viscosity but prolonged setting time and slightly increased bleeding rate,with minor effect on 28 d strength.Ultrafine fly ash also decreased viscos-ity but was unfavorable for shortening setting time or improving 28 d strength.The water-cement ratio had the most pronounced effect on bleeding rate,setting time,and 28 d strength:increasing water-cement ratio improved fluidity but prolonged setting and reduced 28 d strength.Conclusions The developed nano-modified Portland cement-based grouting material demonstrated good fluidity,stability,and mechanical per-formance.These findings provide theoretical and experimental guidance for material selection in practical grouting engineering.