1. objective
Particle shape and surface texture influence the properties of freshly mixed concrete more than the
properties of hardened concrete. Roughtextured, angular, and elongated particles require more water
to produce workable concrete than smooth, rounded compact aggregate. Consequently, the cement content
must also be increased to maintain the watercement ratio. Generally, flat and elongated particles are
avoided or are limited to about 15 % by weight of the total aggregate.

Fig. 1: Balance
Balance should be able to weigh upto 1 g.


Fig. 2: Sieves
Sieves required are 63, 50, 40, 31.5, 25, 20, 16, 12.5, 10 and 6.3 mm (Based on requirement
and Gradation of Aggregate).


Fig. 3: Thickness Gauge For Flakiness Index


Fig. 4: Length Gauge For Elongation Index
Length Gauge have length equal to 1.8 times the mean dimension of the aggregate.

3. reference
IS 2386(Part 1):1963 Methods of Test for Aggregates of Concrete Particle Size and Shape.
Reaffirmed Dec 2016
4. procedure

A quantity of aggregate shall be taken sufficient to provide the minimum number of 200
pieces of any fraction to be tested.

The sample shall be sieved with the sieves specified in Table 1:
Size of Aggregate thickness (mm)

Thickness Gauge * (mm)

Length Gauge ** (mm)

Passing through IS Sieve 
Retained on IS Sieve 
63 
50 
33.90 
 
50 
40 
27.00 
81.0 
40 
25 
19.50 
58.5 
31.5 
25 
16.95 
 
25 
20 
13.50 
40.5 
20 
16 
10.80 
32.4 
16 
12.5 
8.55 
25.6 
12.5 
10 
6.75 
20.2 
10.0 
6.3 
4.89 
14.7 
* This dimension is equal to 0.6 times the mean Sieve size
** This dimension is equal to 1.8 times the mean Sieve size
Table 1 : Dimensions (Length and Thickness) of Gauges

Separation of Flaky material Each fraction shall be gauged in turn for thickness
on a metal gauge of the pattern shown in Fig. 3, or in bulk on sieves having
elongated slots. The width of the slot used in the gauge or sieve shall be of the
dimensions specified in co1. 3 of Table 1 for the appropriate size of material.

The total amount passing the gauge shall be weighed to an accuracy of at least
0.1 percent of the weight of the test sample.

The Flakiness Index is the total weight of the material passing the various thickness
gauges or sieves, expressed as a percentage of the total weight of the sample gauged.

Separation of Elongated Material Each fraction shall be gauged individually for length
on a metal length gauge of the pattern shown in Fig. 4. The gauge length used shall
be that specified in co1. 4 of Table 1 for the appropriate size of material.

The total amount retained by the length gauge shall be weighed to an accuracy of at
least 0.1 percent of the weight of the test sample.

The elongation index is the total weight of the material retained on the various
length gauges, expressed as a percentage of the total weight of the sample gauged.
>
5. observation and recording
Passing through IS Sieves(mm) 
Retained on IS Sieves (mm) 
Flakiness Gauge (mm) 
Weight Passing on Flakiness Gauge (g) 
Percentage Weight Passing (%) 
63 
50 
33.90 


50 
40 
27.00 


40 
25 
19.50 


31.5 
25 
16.95 


25 
20 
13.50 


20 
16 
10.80 


16 
12.5 
8.55 


12.5 
10 
6.75 


10 
6.3 
4.89 




Total 


Table 2 : Recordings for Flakiness Index
Passing through IS Sieves(mm) 
Retained on IS Sieves (mm) 
Elongation Gauge (mm) 
Weight Retained on Elongation Gauge (g) 
Percentage Weight Retained (%) 
63 
50 
 


50 
40 
81.00 


40 
25 
58.5 


31 
25 
 


25 
20 
40.50 


20 
16 
32.4 


16 
12.5 
25.6 


12.5 
10 
20.2 


10 
6.3 
14.7 




Total 


Table 3 : Recordings for Elongation Index
6. calculation

The Flakiness Index on an aggregate is =
Total weight passing Flakiness Gauge x 100 / Total weight of test sample =_________(%)

The Elongation Index on an aggregate is =
Total weight retained on Elongation Gauge x 100 / Total weight of test sample =________(%)