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2023 (English)In: 91st ICOLD Annual MeetingSymposium 13–14 June, 2023 Gothenburg, Sweden: Management for Safe Dams / [ed] Erik Nordström, Stockholm, 2023, p. 1380-1389Conference paper, Poster (with or without abstract) (Refereed)
Abstract [en]
Dam safety measures on the Vattenfall hydropower facility Lilla Edet, in Sweden are, ongoing by replacing parts of the old spillway dam from the 1920s to increase discharge capacity. A climate enhanced concrete without needs for any post-cooling to avoid thermal cracking has been developed for the project. A series of tests from initial laboratory tests via development of a production mix and a full-scale mock-up preceded the construction works on site. Increase of the maximum aggregate sizes from today’s commonly used 27 mm up to 45 mm was introduced to reduce the cement content. Basic tests to verify fresh properties, air void content, strength development, shrinkage etc. was done for a series of different supplementary cementitious materials before selecting fly ash from combustion of pulverized hard coal (PFA) as cement replacement. Examination of the durability aspects like freeze-thaw and carbonation resistance by accelerated test showed no or limited impact on the properties. Development and optimization of the production mix, with use of locally available materials, was done in cooperation with the concrete supplier. The mock-up tests included two large size beams, one with reference concrete and one with the developed concept concrete. Representative reinforcement (dimensions and spacing) was installed, a full-scale concrete pump used and workers from the project executed the casting. The outcome was successful without blockage during pumping, no honeycombing and happy workers. By using installed gauges and optic fibers, early age behavior in terms of temperature and strain development was measured to be able to estimate the risk for thermal cracking. The concept concrete showed to give a substantially reduced riskfor early age thermal cracks in comparison to the reference concrete. With support from the investigations, a decision to deviate from accepted levels of cement replacement in standards was taken. This was possible since the concrete concept proved to fulfill requirements on expected service-life and robustness during construction without cost increase. By using fly ash from combustion of pulverized hard coal as cement replacement, a reduction of the CO2-emissions by almost 30% has been possible and the need for post-cooling has been eliminated completely.
Place, publisher, year, edition, pages
Stockholm: , 2023
National Category
Infrastructure Engineering
Identifiers
urn:nbn:se:kth:diva-334469 (URN)
Conference
91st Annual ICOLD Meeting, Gothenburg, Sweden, 13-14 June 2023
Note
Part of ISBN 978-91-527-8078-7
QC 20231204
2023-08-212023-08-212023-12-12Bibliographically approved