Humboldt H-1684 Flakiness Gauge for Classification of Aggregate - Manual (Page 3)

Discard all aggregate retained on the 63.0 mm BS test sieve and all
aggregate passing the 6.30 mm BS test sieve. Then weigh each of the
individual size-fractions retained on the sieves, other than the 63 mm BS
test sieve, and store them in separate trays with their size marked on the
trays. Where the number of particles in any size fraction is considered to
be excessive i.e. more than the appropriate mass given in Table 1, the
fraction may be subdivided by standard methods. Under such
circumstances the rest of the procedure should be suitably modified, and
the appropriate correction factor applied to determine the mass of flaky
particles that would have been obtained had the whole of the original
size-fraction been gauged.
From the sums of the masses of the fractions in the trays (M
1
), calculate the
individual percentage retained on each of the various sieves. Discard any
fraction of which the mass is 5% or less of mass M
1
. Record the mass
remaining (M
2
).
Gauge each fraction by one of these procedures:
1. Using the gauge: Select the thickness gauge appropriate to the
size-fraction under test (see Table 1) and gauge each particle separately
by hand, or
2. Using the special sieves: Select the special sieve appropriate for the
size-fraction under test. Place the whole of the size-fraction into the
sieve, which shall then be shaken until the majority of flaky particles have
passed through the slots. The gauge the particles retained individually
by hand. Combine and weigh all the particles passing the gauges or
special sieves (M
3
).
E. Calculating & Reporting (Flakiness Index): The Flakiness Index shall be
reported to the nearest whole number. The sieve analysis obtained in the
test shall also be reported.
Flakiness = M
3
x 100
M
2