Glass Fiber Mesh Fabric With Polymer Mortar: Rapid Repair Process For Tunnel Lining Surface Cracks

Tunnel secondary linings are subject to constant structural stress, ground movement, and environmental moisture, all of which eventually manifest as surface cracks. These cracks, if left unsealed, allow water ingress that accelerates rebar corrosion and compromises the long-term durability of the tunnel. For rapid, cost-effective repair, the combination of glass fiber mesh fabric and polymer-modified mortar has become the go-to solution for tunnel maintenance teams worldwide.

The traditional approach-simply filling cracks with neat cement or epoxy-often fails within months because it does not address the underlying tensile stresses that caused the cracking in the first place. Polymer mortar alone can shrink and re-crack, especially in high-humidity underground environments. By embedding glass fiber mesh fabric into a fresh polymer mortar overlay, the repair system gains distributed reinforcement that bridges the crack and spreads tensile forces across a wider zone. The fabric's high tensile strength (typically 400–800 N/50mm) and its excellent bond with the mortar create a composite layer that moves with the substrate, preventing stress concentration and re-cracking at the same location. The alkali-resistant coating on the fabric ensures long-term durability even in the alkaline environment of cement-based mortars.

The "rapid" aspect of this process comes from the polymer mortar itself-fast-setting formulations allow traffic or service to resume within hours, while the mesh fabric accelerates installation by eliminating the need for complicated formwork or anchoring. The sequence of operations is simple and field-proven. Start by cleaning the cracked surface with high-pressure water or abrasive blasting to remove loose particles and laitance. Next, trowel a thin scratch coat of polymer mortar onto the prepared surface. Immediately press the fabric into the wet mortar, overlapping adjacent sheets by at least 10 cm, and lightly embed it with a roller or trowel. Finally, apply a second coat of polymer mortar to completely cover the fabric, followed by a final smoothing pass. The entire operation can be completed in a single shift, making it ideal for overnight or weekend closures.

For tunnel applications, the fabric's resistance to alkali attack is a critical advantage. The alkaline environment of cement-based mortars can deteriorate ordinary glass fibers within months, but a quality glass fiber mesh fabric with proper alkali-resistant treatment maintains its strength for decades. Combined with the polymer mortar's low permeability and high bond strength, the system provides a durable, watertight seal that prevents further deterioration. Field data from numerous tunnel rehabilitation projects show that properly installed fabric-reinforced polymer mortar repairs can extend service life by 15–20 years with minimal maintenance.

For tunnel owners and contractors, the decision is straightforward: glass fiber mesh fabric with polymer mortar offers a proven, rapid, and long-lasting solution for surface crack sealing. It reduces downtime, cuts lifecycle costs, and ensures the structural integrity of critical underground infrastructure.