Numerical approach to assessing the contact characteristics of a polymer-based waterproof membrane

A waterproof membrane sprayed onto concrete enables faster construction compared with a conventional sheet membrane. The sprayed raw material, which is polymer mixed with water, becomes completely continuous waterproof thin membrane after a certain curing time. Such membranes have not been widely used in East Asia due to less confidence of their performance and limited applications despite of their outstanding structural properties and many projects in Europe, especially in the UK (at least 6 projects), which include higher cohesion at the interface and higher tensile strength. This study evaluates the material and contact properties of a waterproof membrane based on the results from laboratory experiments and numerical analyses. Interface properties of the waterproof membrane were calibrated from results of the linear block-support test proposed by European Federation of National Associations Representing for Concrete (EFNARC). A numerical model for simulating three-point bending tests was then developed and used to examine structural effects of the membrane. In results of numerical analysis, the contact conditions between the lining and the membrane had little effect in elastic behaviors, but tensile behavior of concrete lining had a relatively large effect.