Long-term studies on PVC membranes used in tunnels

Building tunnels places very high demands on the durability of all materials used. However, up to now only very few real long-term studies on waterproofing membranes used in tunnels have been carried out. Samples from soft poly(vinyl chloride) membranes with diverse ages of over 40 years were taken during refurbishment programs to ensure safety in various Swiss tunnels. The results of gel permeation chromatography as well as measurements of the plasticizer and gel content showed that all of the membranes have very low polymer degradation or, respectively, none detectable crosslinking of the polymer. The main change determined was the decrease in plasticizer content and the resulting increase in stiffness of the membranes. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46689.