Durability of Phosphate-based Rapid Repairing Material for Tunnel Engineering

Concrete structure in tunnel is apt to deteriorate prematurely and hence a prompt restoration is required. In considering this, desulphurization fly ash and machine made tuff sand were employed to fabricate a phosphate-based rapid repairing material. The long term efficiency of the material was evaluated based on combined factors as drying shrinkage, interfacial bonding strength, corrosion resistance and high temperature resistance. Experimental results showed that the fabricated material manifests an excellent mechanical property. The one hour bending stiffness, compressive strength and bending strength were 9.2, 32.6, 3.3 MPa, respectively. A long term underground water flushing simulation demonstrates that only 10 percent bending strength and corrosion resistance is deduced and the corrosion resistance coefficient stays above 0.6, a very good corrosion resistance is thus achieved. What's more, this repairing material retains its stability even at a high temperature of 1 000℃, reveals its good thermo-stability. All these prominent properties make it a prospect material for real restoration applications.