The relationship between the ratio of the water permeability of
concrete and the fractional replacement by ground bagasse ash is
shown in Fig. 5. The water permeability ratio of concrete decreased
with increasing ground bagasse ash proportion in concrete. At the
age of 28 days, water permeability ratios of 0.92 and 0.82 were obtained
for concretes containing 10% and 20% ground bagasse ash.
This result suggests that small particles of ground bagasse ash
can help to fill the voids in the concrete structure, so that the water
permeability of 35BA10 and 35BA20 was 80–90% of that of the
control concrete. Concrete containing 30% ground bagasse ash
had a water permeability ratio of 0.50 at the age of 28 days due
to the high number of small particles from the ground bagasse
ash filling the voids in the concrete. At 90 days, the water permeability
ratios of 35BA10, 35BA20, and 35BA30 were 0.58, 0.38,
and 0.31, respectively. The low water permeability values of concretes
containing ground bagasse ash at 90 days were mostly
caused by the pozzolanic reaction, which filled up the voids and increased
the concrete density [8].