PSI - Issue 64

Chris Mundell et al. / Procedia Structural Integrity 64 (2024) 191–198 Chris Mundell / Structural Integrity Procedia 00 (2019) 000–000

198

8

samples and extraction of key elements such at the tendon and ducts, samples of concrete in areas of interest and key reinforcement bars for further testing (e.g. reinforcement critical to the half joint strength). The PT ducts are the key elements of interest, which have been cut into 1m to 2m sections, and will be transported to a more controlled environment for opening and inspection. At this time, the ducts will first be inspected, photographed and measured, before being carefully cut and peeled from the grout and tendon. Again, the grout and any exposed tendon will be inspected and documented, with samples of the grout taken for compositional testing. The locations of any identified voids in the grout will be identified for comparison with the NDT findings. Finally, the grout will be mechanically and chemically removed, exposing the individual strands for inspection and testing, again for comparison with specific NDT findings. The majority of the ducts have not yet been opened and inspected, however some exploratory work has already been undertaken, particularly with the ducts extracted from Sample 1. An immediate observation was that the majority of the ducts have suffered deterioration to some extent, and in some cases the ducts were almost entirely non-existent along large lengths of the exposed ducts. Furthermore, the mortar was found to be missing or of very poor quality. Where the ducts were intact with grout present, a small number were cut and opened to expose the tendons and grout. In these cases, the grout was found to be of uniformly low strength, extremely soft and friable, and purely the removal of the duct was enough to cause the mortar to disintegrate and peel away from both strands and duct. This will be key area for further study, including the chemical composition of the grout and its remaining strength. 4. Summary and Conclusions Although still in progress, the project has already yielded significant insights and progress. The low TRL technologies explored by Omnia and Sentec are each pushing boundaries of what is achievable, particularly in the field of guided waves. In this aspect of the project, progression of the technologies will now start moving from what is theoretically possible to the practicalities of deployment in a real situation, and the relative value derived from its application. Again, with respect to the NDT trials of the A14, although the data collation and assessment is still underway, a number of interesting observations and avenues have already been identified, and a broad suite of NDT techniques deployed. The industry engagement has also been very strong, with the NDT providers engaged being both collaborative and inquisitive, which has allowed the collation of information to be much broader than initially anticipated, which will in turn yield greater insights as the project turns to the data assessment. Acknowledgements The Authors would like to thank all of the parties involved in this project to date. These include the client and project sponsors National Highways (and the funding by National Highways’ designated funds for Innovation and Modernisation Fund), the AtkinsRealis and Jacobs joint venture project team, Main works contractor VSL, R&D partners Sentec (supported by Lucy Electric) and Omnia (supported by Vallen Systeme and ARCES) and NDT specialists Mistras, Bridgology, CTS, Allied Associates, Screening Eagle, the Royal Agricultural University (supported by the University of Bristol and Pro-Lite Technology), Hausbots, Hilti, GScan and IFDB. REFERENCES

AECOM. 2021 – Huntingdon Railway Viaduct Research Feasibility (Rev 003). Highways England Atkins. 2020. Post-Tensioned Non-Destructive Testing and Monitoring Techniques. Highways England. Atkins. 2023. Task 164. Management of High Priority Structures – RIS3 Funding Estimate (Rev 2). National Highways