Humboldt H-1684 Flakiness Gauge for Classification of Aggregate - Manual (Page 2)

Introduction
This method is based on the classification of aggregate particles as flaky when
they have a thickness (smallest dimension) of less than 0.6 of their nominal
size, this size being taken as the mean of the limiting sieve apertures used for
determining the size fraction in which the particle occurs. The flakiness Index of
an aggregate sample is found by separating the flaky particles and expressing
their mass as a percentage of the mass of the sample tested. The test is not
applicable to material passing a 6.30 mm BS test sieve or retained on a
63.0 mm BS test sieve.
Apparatus
The following apparatus is required.
1. A metal thickness gauge of the pattern shown in Figure 5 or special
sieves having elongated apertures. The width of the apertures and the
thickness of the sheet used in the gauge or sieve shall be as specified
in Figure 1.
2. BS test sieves as shown in Table 9 as appropriate.
3. A balance accurate to 0.5% of mass of the test sample.
C. Sample for test:
The sample for this test shall be taken in accordance with BS 812. It shall
comply with the appropriate minimum mass, for sieve analysis with due
allowance for 63.0 mm BS test sieve and passing a 6.30 mm BS test sieve.
The sample shall be taken from the laboratory sample by quartering or by
means of a sample divider. Before testing it shall be brought to a dry
condition by standard methods.
D. Procedure:
Carry out a sieve analysis using the sieves given in Table 1.
Figure 1— Thickness Gauge (Flakiness Index) indicating sizes of openings.