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Microscopic investigations

A series of microscopic investigations have been carried out in connection with the testing program for the 15 concrete blocks exposed to a marine environment at the Fehmarnbelt exposure site at Rødbyhavn. The concretes were examined after 28 days of curing, i.e. before exposure to seawater, and subsequently after 6 months and 2 years of seawater exposure. All studied thin sections and polished samples were prepared from drilled cores.

The investigations undertaken after 6 months and 2 years of exposure also included three additional types of concretes with binders consisting of BASIS Portland cement, Rapid Portland cement and Rapid Portland cement + 25% fly ash, respectively. These concretes were cast as cylinders in connections with the production of the large concrete blocks to be exposed at Rødbyhavn. The cylinders were exposed to seawater at the same time as the large blocks.

Results from the investigations have been collected in datasheets that contain the most important observations from the optical microscopy. Furthermore, the datasheets for samples examined after 6 months and 2 years of exposure also include data obtained by scanning electron microscopy (SEM) in combination with Energy-Dispersive X-ray (EDX) spectroscopy. The datasheets can be downloaded here:

DownloadFehmarn exposure site_microscopic investigations_28 days (4,1 MB)

DownloadFehmarn exposure site_microscopic investigations_6 months (6,8 MB)

DownloadFehmarn exposure site_microscopic investigations_2 years (8,4 MB)

Main results from the microscopic investigations have also been presented at the Nanocem Fall Meeting, 25-57 November 2011 in Paris. Pictures of the exposed concrete blocks, illustration of the sampling procedure, essential results, etc. are included in the slides from this presentation, which can be downloaded here:

DownloadStudy of Fehmarn Belt Trial Concretes_6 months results_Nanocem presentation (4,5 MB)

Finally, results from the microscopy investigations of the concrete blocks exposed at Rødbyhavn Harbour have been presented in a paper prepared in connection with the 14th Euroseminar on Microscopy Applied to Building Materials (2013):

DownloadMicrostructural surface deterioration of concrete exposed to seawater (639 KB) - Results after 2 years exposure