4.4.2 Applied compaction methods
Aggregate fractions of the same batch were used throughout the research project on
SCFRC; the composition of the sand and the coarse aggregates was kept constant. The
composition was based on Vol.-%. The aggregates were dried in an oven at 105°C for
24 hours. In advance, the packing density was roughly estimated and the quantity of
each fraction and/or steel fibres (with 15% surplus) was weighted out for the test. The
aggregates were carefully mixed by hand for at least 60 s. The fibres were added and
remixed for further 60 s or until they appeared homogenously distributed. Hoy [1998]
also applied hand mixing in his experiments; it is questionable whether mixing in a
mixer will produce a better distribution in case fibres are added; fibres also might bend
due to the mixing process.