Performance Evaluation of Modified Cement-Sodium Silicate Grouting Material for Prereinforcing Loose Deposit Tunnels

Abstract

In grouting practices for tunneling in loose deposits, the traditional grouting materials often suffer from its disadvantages, such as prolonged gel times, poor stability, an uncontrollable range of diffusion, and large grout consumption. In this study, an organic–inorganic hybrid chemical grouting material based on polymerization of hydrogen double bonds, Ca-C connection and excellent synergistic interactions among cement, polyethylene glycol (PEG) 200, sodium silicate, and polycarboxylate superplasticizer (PS) was prepared with a simple process. Based on percentages of water/cement at 1, PEG200 (2%), sodium silicate (10%), and PS (0.2%), the obtained modified cement-sodium silicate grouting material (C-S-P) forms a three-dimensional network structure and results in a high stability, good pumpability, satisfactory initial compressive strength, and relatively lower permeability performance. The C-S-P was primarily composed of amorphous PEG and crystalline polysilicic Ca(OH)2/Ca2SiO4/SiO2/CaCO3 composite, and its probable formation mechanism was evaluated. The proposed new grouting material was applied for reinforcing a tunnel in loose deposits, and the results illustrate that the C-S-P turns out excellent grouting performance and mechanical performance, thereby fulfilling the requirements for tunnel rapid excavation in loose deposits. This study presents the methodology for preparing a new grouting material for reinforcing loose deposits.