{"id":1966,"date":"2025-11-06T14:52:35","date_gmt":"2025-11-06T13:52:35","guid":{"rendered":"https:\/\/www.invator.se\/projekt\/special-inspection-of-tension-cables-in-maloybrua-norway\/"},"modified":"2026-04-10T11:34:55","modified_gmt":"2026-04-10T09:34:55","slug":"special-inspection-of-tension-cables-in-maloybrua-norway","status":"publish","type":"projekt","link":"https:\/\/www.invator.se\/en\/projekt\/special-inspection-of-tension-cables-in-maloybrua-norway\/","title":{"rendered":"Special inspection of tension cables in M\u00e5l\u00f8ybrua, Norway"},"content":{"rendered":"\n

Problem<\/strong>The M\u00e5l\u00f8y Bridge is a 1224 meter long concrete box girder bridge built in the early 1970s. Previous reports indicated problems in the grouting of the post-tensioned cables, with suspicions of incomplete filling in some casings. The purpose of the assignment was to conduct a special inspection to locate cables, assess the status of the grout and identify any voids and risks of corrosion. <\/p>\n\n

\"\"\n
The examination revealed that one casing was completely empty and had corrosion on the tensioning wires.<\/em><\/figcaption>\n<\/figure>\n\n

<\/p>\n\n

Results<\/strong>The survey covered 12 predefined positions. The results showed that one channel (L9, liner 4) was completely empty and had corrosion on the tensioning wires. Otherwise, only minor voids and local separations of the grout were noted. A number of casings had traces of diesel in the grout, probably from wintertime additives during the construction phase. In summary, it was found that the majority of the cables were correctly grouted, but that individual deviations require further mapping and continued maintenance measures. <\/strong><\/p>\n\n

\"\"\n
Core drilling to open and visually verify the status of cables.<\/em><\/figcaption>\n<\/figure>\n\n

<\/p>\n\n

Solution<\/strong>The special inspection was carried out in the following steps:<\/p>\n\n

    \n
  • Review of drawings and planning of measurement points.<\/li>\n\n\n\n
  • Locating tension cables with GPR and strain gauges.<\/li>\n\n\n\n
  • Ultrasound tomography (MIRA) with about 3000 B-scans along the cables.<\/li>\n\n\n\n
  • Impact Echo for verification of suspected voids.<\/li>\n\n\n\n
  • Processing of data from non-destructive testing<\/li>\n\n\n\n
  • Core drilling in eight locations to open and visually verify the status of the cables.<\/li>\n\n\n\n
  • Borehole repair with Mapei system (Redisit, Redirep 45 RSF).<\/li>\n<\/ul>\n\n

    The method combination of non-destructive testing (NDT) and core drilling provided a high degree of confidence in the assessment.<\/p>\n\n

    \"\"\n
    Interior view of M\u00e5l\u00f6ybrua.<\/em><\/figcaption>\n<\/figure>\n\n

    <\/p>\n\n

    Equipment<\/strong><\/p>\n\n

      \n
    • Coating thickness gauge (Profoscope+)<\/li>\n\n\n\n
    • Ground Penetrating Radar (Proceq GP8000\/8800)<\/li>\n\n\n\n
    • Ultrasound tomography (MIRA Tomographer)<\/li>\n\n\n\n
    • Impact Echo (DOCter)<\/li>\n\n\n\n
    • Videoscope<\/li>\n\n\n\n
    • Core drills and forming equipment<\/li>\n\n\n\n
    • Drones (for external inspection)<\/li>\n<\/ul>\n\n

      Standards<\/strong><\/p>\n\n

        \n
      • EN 1990: Eurocode – Basic rules<\/li>\n\n\n\n
      • EN 1991-1-1: Eurocode 1 – Loads on structures<\/li>\n\n\n\n
      • EN 1992-1-1: Eurocode 2 – Concrete structures<\/li>\n\n\n\n
      • ISO 16311-1\/2 – Condition assessment of concrete structures<\/li>\n\n\n\n
      • Public Roads Administration Inspection Manual No. 718 (2021)<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"

        Following suspicions of inadequate grouting of tension cables in the M\u00e5l\u00f8y Bridge, a special inspection was carried out to map the position and status of the cables. The investigation showed that one channel was completely empty with corroded wires, while the others had minor voids and separations. <\/p>\n","protected":false},"featured_media":1596,"template":"","meta":{"_acf_changed":false},"bransch":[19],"class_list":["post-1966","projekt","type-projekt","status-publish","has-post-thumbnail","hentry","bransch-construction"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.invator.se\/en\/wp-json\/wp\/v2\/projekt\/1966","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.invator.se\/en\/wp-json\/wp\/v2\/projekt"}],"about":[{"href":"https:\/\/www.invator.se\/en\/wp-json\/wp\/v2\/types\/projekt"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.invator.se\/en\/wp-json\/wp\/v2\/media\/1596"}],"wp:attachment":[{"href":"https:\/\/www.invator.se\/en\/wp-json\/wp\/v2\/media?parent=1966"}],"wp:term":[{"taxonomy":"bransch","embeddable":true,"href":"https:\/\/www.invator.se\/en\/wp-json\/wp\/v2\/bransch?post=1966"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}