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<p>Grouting materials are widely used in tunnelling projects. Due to their short history of application, polyurethane/water glass (PU/WG) grouting materials have a dual limitation: insufficient knowledge of the mechanism and lack of tunability of the formulation system. This study systematically examines how catalyst dosage and isocyanate-to-WG mass ratio affect PU/WG composites’ curing behavior, mechanical properties, and microstructure. The key findings are: (1) elevating catalyst dosage (0.1–0.6&#xa0;g) shortens gel time and curing time by 80–90% while boosting compressive strength 40–60% due to the formation of dense, uniformly distributed silicate microspheres (25–45&#xa0;μm); (2) the isocyanate-to-WG mass ratio plays a pivotal role in reaction completeness, where optimal ratios (0.6–0.9) ensure maximum CO<sub>2</sub> generation and silicate conversion for enhanced mechanical performance; and (3) the optimized formulation (PAPI: 45.99%, WG: 51.10%, catalyst: 0.36%, plasticizer: 2.55%) delivers both rapid curing (gel time: 190–200&#xa0;s; curing time: 270–290&#xa0;s) and outstanding compressive strength (70–75&#xa0;MPa), with field-adjustable catalyst content (0.6–0.9&#xa0;g) for customized setting times. These results offer fundamental insights into PU/WG composite mechanisms and present a tunable formulation approach to meet the critical demand for adaptive grouting materials in tunnel engineering.</p>

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Mechanical Properties and Microstructure of Polyurethane/Water Glass Composites for Tunnel Grouting in Water-Rich Formations

  • 期刊论文

  • 发表日期：

    2025年7月16日

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  • Qihang Ran,
  • Yifan Jiang,
  • Ruilong Wang,
  • Jiapeng Pu,
  • Lang Bi,
  • Yong Fang,
  • Lai Sun

摘要

Grouting materials are widely used in tunnelling projects. Due to their short history of application, polyurethane/water glass (PU/WG) grouting materials have a dual limitation: insufficient knowledge of the mechanism and lack of tunability of the formulation system. This study systematically examines how catalyst dosage and isocyanate-to-WG mass ratio affect PU/WG composites’ curing behavior, mechanical properties, and microstructure. The key findings are: (1) elevating catalyst dosage (0.1–0.6 g) shortens gel time and curing time by 80–90% while boosting compressive strength 40–60% due to the formation of dense, uniformly distributed silicate microspheres (25–45 μm); (2) the isocyanate-to-WG mass ratio plays a pivotal role in reaction completeness, where optimal ratios (0.6–0.9) ensure maximum CO2 generation and silicate conversion for enhanced mechanical performance; and (3) the optimized formulation (PAPI: 45.99%, WG: 51.10%, catalyst: 0.36%, plasticizer: 2.55%) delivers both rapid curing (gel time: 190–200 s; curing time: 270–290 s) and outstanding compressive strength (70–75 MPa), with field-adjustable catalyst content (0.6–0.9 g) for customized setting times. These results offer fundamental insights into PU/WG composite mechanisms and present a tunable formulation approach to meet the critical demand for adaptive grouting materials in tunnel engineering.