STP1076: The Use of Thermal Analysis for the Evaluation of the Durability of a 24-Year-Old PVC Geomembrane

    Cazzuffi, DA
    ENEL Research Centre on Hydraulics and Structures, Milan,

    Venesia, S
    ENEL Research Centre on Hydraulics and Structures, Milan,

    Pages: 9    Published: Jan 1990


    Abstract

    The paper deals with the behavior of a geomembrane installed in 1963 for the internal waterproofing of a concrete pipe in a hydroelectric project. The type of geomembrane used was polyvinyl chloride (PVC), directly glued to the concrete support. The PVC geomembrane was directly exposed to the water; the water temperature in the pipe is usually 4°C in winter and 9°C in summer. The maximum waterspeed is 3 m/s, and the maximum water pressure is 0.6 MPa.

    A first sampling of the PVC was carried out in 1973. A second sample was removed in 1987. The first sample was stored in a room for 14 years in controlled conditions. Thermal analysis on both geomembrane samples was performed in 1987 to assess the performance of the material over the 24-year period since installation.

    Thermal-gravimetric analysis (TGA), differential scanning calorimetry (DSC), thermomechanical analysis (TMA), and dynamic mechanical analysis (DMA) were performed. Only small differences between the two samples were recorded, by TGA and DSC. However, TMA showed an increase in the softening temperature from 27°C in 1973 to 34°C in 1987. In addition, DMA showed an increase of the dynamic loss modulus of about 24% at the installed geomembrane operating temperature (from 4 to 9°C).

    Keywords:

    geomembrane, performance, polymer microstructure, thermal analysis, hydroelectric plant, concrete pipe, waterproofing


    Paper ID: STP23493S

    Committee/Subcommittee: D35.10

    DOI: 10.1520/STP23493S


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