Weigh 2500 g aggregate which the absorption coefficient, the
dust content are known.
Weigh 588.15 g of cement and 211.73 g of water.
Mix with a small mixer for 5 min.
Discharge the fresh concrete to a metal sieve. The holes diameter
depends on the size of aggregates. Indeed, the choice of
holes diameter is to simulate the pore size of concrete. The pore
size of the pervious concrete depending on the size of aggregates,
as shown in equation [21]: Dp = 1.44 + 0.36 Di. For
example, with the average size of 5.125 mm, a sieve with holes
size of 3 mm can be used.
Vibrate the metal sieve for 15 s with a vibrating table. The
choice of the vibration time depends on the execution method
used in situ or in the precast plant and is normally longer than
the time spent on field or in the factory.
Keep an eye on the bottom of the sieve. If a lot of cement paste
sticks to the bottom (the cement paste too liquid), w/c is not
appropriate.
Collect the concrete on top layer of fresh concrete in sieve, measuring
the weight denoted M1. The top layer of concrete is chosen
because it shows the amount of cement paste can coat the
aggregate under in the compaction effort.
Rinse with water to remove all the fresh concrete cement paste
to avoid lost of grain gravel.
Dry the gravel for 24 h at 105 C and weigh the mass M2.
By subtracting the content dust, the mass of cement paste coats
the gravel is M3 = M1 (1 + b/100) M2.
Calculate the volume of cement paste VP from the mass of
cement paste M3 and the ratio w/c used in the test.
Determinate the thickness of the cement paste e = VP/S. S is the
total surface area of aggregate. S can be determined using the
factor specific surface area of aggregate (Table 4) [22] or can
be calculated assuming the aggregate in spherical form with
size Di.
Calculate the volume content of cement paste from the volume
of aggregate.
In conclusion, with the drainage test, the w/c can be determined
to prevent the flow of cement paste. In addition, it can be used to
determine the amount of cement paste needed to coat the gravel,
consequently the content of the cement paste in pervious concrete.
3. Procedures of the proposed mix proportioning method
Proportioning procedure of the proposed method is as
following:
1. Required data on coarse aggregate: Gradation, dry
compacted bulk density, specify bulk density, absorption,
compactness by shake-table compactness testing of LCPC