Mix proportion and properties of fire-resistant wet-mixed high-strength polypropylene fiber-reinforced sprayed polymer cement composites

This study examined the optimal mix proportions and performance of a fire-resistant wet-mixed high-strength fiber-reinforced polymer cement composite that enhances the fire-resistance of underground structures. A mix ratio was determined through preliminary tests to satisfy the target compressive strength and maintain the minimum thermal conductivity. A mix with 10% silica fume, 30% perlite replacement ratios and 0.2% of polypropylene fiber satisfied the desired standards. The polymer cement composite had high compressive, flexural, and bond strengths of approximately 40, 5, and 1.6 MPa, which are sufficient for the surface pressures encountered in road and railway tunnels.