The vertical flow rate test is a simple yet
effective assessment of whether a concrete mix of specific proportions
is sufficiently but not excessively fluid. If the vertical flow
rate is too high, an accumulation of cement paste will cause a
blockage at the bottom of the pervious concrete, thereby affecting
its permeability. Figs. 2 and 3 show the loss rate of the slurry for 25
and 50 vibrations, respectively. Except for the 0.30 w/c ratio mix,
which did not exhibit a significant vertical flow phenomenon