In Q2 of 2017 DTI produced nine large beams for Femern A/S. All nine beams were produced with a concrete similar to mix C “High Flyash” used for the exposure site. Each beam required the production of 1.6 m3 of concrete, i.e. seven batches using the DTI concrete mixing station.
The nominal mix design used was the same as for the exposure site. The cement used was the same brand name from Aalborg Portland as was used in 2009/2010, however, the cement is now produced in a different kiln. Likewise the fly ash was the same brand name from Emineral as in 2009/2010, however, the ash was originating from a different power station. Fine aggregate was Storebæltssand 0/2 from NCC Industri. It was dredged at Bakkegrund Syd rather than Rønne Banke. However, test results showed that the grain size distribution and mineralogy was very similar to the fine aggregate used in 2009/2010. The course aggregate was as in 2009/2010 crushed Rønne granite from NCC Industri. The new batch had a higher absorption than in 2009/2010. The air entraining admixture was the same (MasterAir 22SB), whereas the superplasticizer was MasterGlenium SKY 631.
The development in mechanical properties of the concrete in terms of compressive strength (EN 12390-3), splitting tensile strength (EN 12390-6), pure tensile strength and E-modulus (DS 423.25) was determined on a single 250 litre batch. The water to cement ratio of the concrete was 0,398 and the air content 5.0%. The mechanical properties determined are found in the table below.