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  Testing of properties and constructability considerations of EVA based sprayed membranes for waterproofing of tunnels

  Site and laboratory testing of sprayed concrete linings waterproofed with spray-applied membrane has been carried out over a period of 3 years. The site testing has been carried out in several full scale test sections as well as a longer section of a rail tunnel in hard rock in Norway. The linings were tested for moisture content and tensile bonding strength. The results of the site testing indi- cate that there is no full water saturation of the sprayed concrete and membrane materials in the tunnel linings, in spite of exposure to a certain but low groundwater pressure. A gradient in degree of saturation of the concrete material from the rock surface towards the lining surface and low moisture contents in the sprayed membrane material has been consistently recorded. The testing was carried out at several times with one year intervals with age up to 4 years after construction. Thus, a development over time could be investigated. The moisture content in the membrane ma- terial shows a favourable development over time, with a slight decrease. Values for moisture con- tent in the membrane material have found to be around 12-17% by weight, which corresponds to 30-35% of the maximum possible moisture content. Consistently high tensile bonding strengths at the membrane-concrete interfaces in the range of 1.2 -1.3 MPa have been measured.

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