What does this research mean for the field?

A high-performance grouting material utilizing shield muck with TMS-Na enhances compressive strength by approximately 97.4% at 3 days and 93.3% at 28 days compared to conventional grouts. Novelty: ClaimNovelty.NOVEL_FINDING. Consensus alignment: ConsensusAlignment.CHALLENGES_CONSENSUS.

What question did this study set out to answer?

This research aims to create a sustainable grouting material using excavated soil to enhance the efficiency of shield tunneling.

February 19, 2026Open Access

Reutilization of Silty Sandstone Shield Spoil for Sustainable Synchronous Grouting: Mechanical Properties and Microstructure Characterization

Key Points

This research aims to create a sustainable grouting material using excavated soil to enhance the efficiency of shield tunneling.
Developed a grouting material using shield muck and sodium trimethylsilanolate (TMS-Na)
Conducted orthogonal experiments to assess the impacts of ingredients on performance
Analyzed microstructure with SEM, XRD, FTIR, TG, and MIP
Evaluated workability and mechanical properties of the novel grout
Incorporating 8% slag and 0.2% TMS-Na increased shield muck utilization to 60.8%
Achieved enhancements of 97.4% and 93.3% in compressive strength at 3 and 28 days, respectively
Enhanced impermeability grade reached P10
Confirmed effectiveness in preventing water leakage and controlling ground deformation in field trials

Abstract

Conventional synchronous grouting materials often exhibit low early strength, delayed setting, and insufficient utilization of excavated soil, hindering the green and efficient advancement of metro shield tunneling technology. To overcome these challenges, this study developed a high-performance grouting material by utilizing shield muck—primarily composed of quartz (71.47%) and calcite (15.3%)—as the main raw material, with sodium trimethylsilanolate (TMS-Na) introduced as a performance enhancer. Through orthogonal experiments and range analysis, the influences of cement content, slag content, and TMS-Na dosage on the workability and mechanical properties of synchronous grouting materials were systematically evaluated. Microstructural evolution was characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric (TG) analysis, and mercury intrusion porosimetry (MIP) to elucidate the mechanism by which TMS-Na modifies the grout microstructure. The results demonstrate that incorporating 8% slag and 0.2% TMS-Na increases the utilization rate of shield muck to 60.8%. Compared with conventional grouts, the novel material exhibits approximately 97.4% and 93.3% enhancements in 3-day and 28-day compressive strength, respectively, alongside an impermeability grade reaching P10. The addition of slag improves the apparent density and early strength of the grout, although its contribution diminishes at later ages. TMS-Na effectively activates the hydration reactivity of slag, accelerates early hydration, reduces the setting time, and participates in a secondary hydration reaction with argillaceous siltstone present in the excavated soil, promoting the formation of additional calcium silicate hydrate (C-S-H). This process densifies the hardened grout matrix, refines the pore structure, and significantly enhances both mechanical performance and impermeability. Field application in a trial tunnel section confirms that the proposed grouting material achieves complete cavity filling, eliminates water leakage, controls ground deformation effectively, and offers favorable economic viability, demonstrating strong potential for large-scale engineering application.

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