Page 27 - HIGHWAY ENGINEERING LABORATORY_FLIP BUILDER

Page :
WORK INSTRUCTION
Edition :
Checking No.
FLAKINESS AND
ELONGATION INDEX TEST
CIVIL ENGINEERING Reference Standard: BS 812: Effective Date:
Section 105.1 :1989
JKA/ DCC30112/ 2021 Amendment Date:

1.0 OBJECTIVE OF EXPERIMENT :
To determine the percentage of flat particles in a seal coat aggregate

. 2.0 SUMMARY OF THEORY :

The particle shape of aggregates is determined by the percentages of flaky and
elongated particles contained in it. For base course and construction of bituminous and
cement concrete types, the presence of flaky and elongated particles are considered

undesirable as these cause inherent weakness with possibilities of breaking down under
heavy loads. Thus, evaluation of shape of the particles, particularly with reference to
flakiness and elongation is necessary.

The Flakiness index of aggregates is the percentage by weight of particles whose
least dimension (thickness) is less than three- fifths (0.6times) of their mean dimension. This
test is not applicable to sizes smaller than 6.3mm.

The Elongation index of an aggregate is the percentage by weight of particles
whose greatest dimension (length) is greater than nine-fifths (1.8times) their mean
dimension. This test is not applicable for sizes smaller than 6.3mm.

3.0 DETAILED PROCEDURE : FLAKINESS INDEX TEST

WORK PROCESS REFERENCE
DOCUMENT
EQUIPMENT SET UP: Reference
Standard:
BS 812:
Section 105.1
:1989

Seive Flakines Gauge Weighing Balance

Higway Engineering Laboratory page 14