Preparation and Performance Evaluation of Fiber Polyurethane/Water Glass Grouting Materials

Fiber‐reinforced polyurethane/water glass (PU/WG) grouting materials possess excellent mechanical and rheological properties, making them highly promising materials for rapid and durable tunnel structural repair. In this study, we investigated the time‐varying viscosity law, setting time, strength evolution law, uniaxial compressive strength (UCS), and material performance characteristics of a new PU/WG grouting material. A new fiber PU/WG grouting material was developed by using an orthogonal experimental method to determine the optimal component ratio at which the material exhibited the following properties: a sudden change time node for the grout viscosity and setting time of 120 and 177 s, respectively. The UCS of the consolidated grout samples increased rapidly within 2 h, before stabilizing at a lower rate. After 28 days of curing, the UCS exceeded 70 MPa. A decrease in the number of internal pores and average pore size, coupled with a more uniform pore distribution, resulted in improved overall mechanical properties. These results indicate that the proposed fiber PU/WG grouting material was an ideal material for tunnel structural repair.