Preparation and application research of hybrid alkali-resistant glass fiber reinforced cement grout

Cement grouting reinforcement is a widely used method for controlling water inrush in tunnels. However, traditional cement grout has certain limitations such as low strength and susceptibility to erosion, which can result in inadequate grouting performance in water-rich tunnels. To address this issue, this study introduces a novel type of grout called hybrid alkali-resistant glass fiber reinforced cement grout (HARGFC). In order to evaluate its effectiveness, different ratios of HARGFC were tested in terms of slurry fluidity, splitting tensile strength, compressive strength, and flexural strength through laboratory experiments. Additionally, microscopic analysis of the samples was carried out using scanning electron microscopy (SEM) in conjunction with the mechanical tests. Finally, the application of HARGFC was demonstrated in a water-blocking grouting project conducted in the Qiyue Mountain Tunnel on the Liwan Expressway. The results demonstrated that this material possesses outstanding physical and mechanical properties, as well as alkali resistance, which greatly enhances grouting performance in water-flowing tunnels. Adding a total fiber content of 1%, that is, 80% of Cem-FIL70 (9 mm) and 20% of HD (6 mm), yielded the optimal ratio for HARGFC. Compared to traditional cement materials, the splitting tensile strength, flexural strength, and compressive strength of the new material increased by 27.46%, 20.64%, and 7.37%, respectively. Building upon various combinations of grouting methods, the optimal HARGFC was applied to the grouting sealing and reinforcement of the Qiyue Mountain Tunnel, effectively controlling water inflow. These research findings provide valuable data and theoretical support for addressing sudden water inrush in tunnels and grouting construction.