Chapter: Civil : Highway Planning and Alignment : Highway Construction Materials And Practice
Highway Construction: Shape tests
Shape tests
The
particle shape of the aggregate mass is determined by the percentage of flaky and
elongated particles in it. Aggregates which are flaky or elongated are
detrimental to higher workability and stability of mixes.
Flakiness
gauge
The
flakiness index is defined as the percentage by weight of aggregate particles
whose least dimension is less than 0.6 times their mean size. Test procedure
had been standardized in India (IS:2386 part-I).
Elongation gauge
The
elongation index of an aggregate is defined as the percentage by weight of particles
whose greatest dimension (length) is 1.8 times their mean dimension. This test
is applicable to aggregates larger than 6.3 mm. This test is also specified in
(IS:2386 Part-I). However there are no recognized limits for the elongation
index.
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