ABSTRACT
Durability of waterproofing systems used in tunnels is of main importance because water highly influences durability, effectiveness and maintenance costs of underground structures. PVC-P geomembranes are one of the most applied technologies for tunnel waterproofing, nonetheless there is a lack of knowledge on their durability in underground applications. Even if long-term durability of PVC-P geomembranes has been analysed for outdoor applications (e.g. dams, roofs), few information are available for applications in underground conditions. In this paper the durability of two commercial PVC-P geomembranes for tunnelling applications is analysed based on the results on laboratory tests. Plasticizer absorption tests and mechanical tests are performed on the commercial geomembranes and on eight formulations of PVC-P specifically produced. The results of those tests permit to study the long-term degradation due to plasticizer loss and extrapolate the losses in time. Finally, an end-of-life time for the geomembranes has been defined merging mechanical requirements for the membrane and the long-term evolution of the degradation of the properties.
