Conditions on the Application of Sprayable waterproofing Membrane in Tunnels under Sulfate Attack Environments

摘要

Spray-on membrane is a new waterproofing system in tunnels. The conditions of the application of this system under sulfate attack environments are analyzed in terms of the deformation and surface condition of the first layer of the shotcrete shell, water ingress and water pressure behind the waterproofing membrane; as well as the mechanism of sulfate attack in concrete, the features of the interaction of the sulfate bearing ground water with shotcrete linings. The results show that the applications of a spray-on waterproofing membrane in a tunnel is possible if the deformation, the durability and specification of materials of the shotcrete and water pressures behind the sprayed membrane are properly controlled. Measures to meet the conditions are presented for the application of the membranes in tunnels.