illustrate the variations of the slump and slump flow of the concrete composite with 15% fly ash and 6% silica fume
with the increase of polypropylene fiber volume fraction, respectively. It can be seen from the figures that the addition of polypropylene fiber decreases the slump and slump flow of the concrete composite with 15% fly ash and 6% silica fume. With the increase of fiber volume fraction, both of the slump and slump flow are decreasing gradually. Compared with the concrete composite without polypropylene fiber, the decrease of the slump and slump flow were determined as 7.7% and 10.7% for the concrete composite with 0.12% fiber volume fraction respectively. For the slump,
there is a sharp decrease when the fiber volume fraction increases from 0.08% to 0.1%. With the increase of fiber volume fraction, the
number of fibers in unit concrete mixture becomes larger, and the
water absorbed on the surface of the fibers becomes more. Therefore,
the obstructive effect of fibers on the flowability of fresh concrete
becomes much larger. The addition of polypropylene fiber
may be adverse to the workability of fresh concrete containing
fly ash and silica fume. The same conclusion on concrete without
fly ash and silica fume can be drawn based on the existing research
results