TY - CONF A1 - Lay, Vera A1 - Baensch, Franziska A1 - Hofmann, Detlef A1 - Mielentz, Frank A1 - Sturm, Patrick A1 - Prabhakara, Prathik A1 - Johann, Sergej A1 - Kühne, Hans-Carsten A1 - Niederleithinger, Ernst T1 - New materials and innovative monitoring for safe sealing structures in underground repositories N2 - Within the project SealWasteSafe, we advance construction materials and monitoring concepts of sealing structures applied for underground disposal of nuclear waste. As these engineered barriers have high demands concerning integrity, an innovative alkali-activated material (AAM) is improved and tested on various laboratory scales that is highly suitable for the application in salt as a host rock. This AAM has a low reaction kinetics related to a preferential slow release of the heat of reaction in comparison to alternative salt concretes based on Portland cement or magnesium oxychloride cements. Hence, crack formation due to thermally induced strain is reduced. A comprehensive multi-sensory monitoring scheme is developed and investigated to compare the setting process of AAM and salt concrete for manufactured specimens (100-300 l). The analysed parameters include temperature and humidity of the material, acoustic emissions, and strain variations recorded by fiber optic cables. Passive sensor systems based on radiofrequency identification technology (RFID) embedded in the concrete allow for wireless access and are compared to conventional cabled systems for temperature and humidity measurements. Furthermore, ultrasonic methods are used for quality assurance to detect obstacles, potential cracks and delamination. Field layout and applied imaging techniques are optimised to enhance the image quality. To characterise the inside of the test engineered barrier and achieve a proof-of-concept, an ultrasonic borehole probe is developed to allow for phased arrays that can further improve the detection of potential cracks. Modelling results and first analysis of half-spherical specimen prove the reliability of the directional response caused by the phased arrays of the newly constructed ultrasonic borehole probe. Overall, the project SealWasteSafe improves the construction material, multi-sensory monitoring concepts and ultrasonics for quality assurance. Particularly for salt as a host rock, this will help to develop safe sealing structures for nuclear waste disposal. T2 - 9th IGD-TP Symposium CY - Zurich, Switzerland DA - 20.09.2022 KW - SealWasteSafe KW - Monitoring KW - Engineered barrier systems KW - Alkali-activated material KW - Ultrasonic inspection PY - 2022 AN - OPUS4-55826 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -