Flakiness Index Test 284w6n

Pavements & Structures

TEST METHOD

WA 216.1

FLAKINESS INDEX SCOPE This method describes the procedure for the determination of the Flakiness Index of aggregate that has not more than 5% retained on a 26.5mm AS Test Sieve and no more than 5% ing a 4.75mm AS Test Sieve. DEFINITIONS 1.

The Flakiness Index is the percentage, by mass, of the particles whose least dimension is less than three-fifths of the mean dimension.

2.

The Mean Dimension is the arithmetic mean of the smallest sieve aperture size through which the particle es and the next smallest sieve aperture size on which the particle is retained (Note a).

APPARATUS 1.

Slot gauge, essential dimensions complying with Figure 1.

2.

Balance of at least 3kg capacity readable to 0.1 g or better, with a Limit of Performance (F) of less than or equal to 0.6 g.

3.

Sample divider of the multiple slot type. A suitable design is shown in Figure 2 (optional).

4.

Worksheet, MRD 1201 (optional).

PROCEDURE 1.

Obtain a test sample taken in accordance with Test Method WA 200.1.

2.

Determine the particle size distribution of a test portion in accordance with Test Method WA 210.1 and after sieving keep the 26.5 - 19.0mm, 19.0 13.2mm (Note a), 13.2 - 9.50mm, 9.50 - 6.70mm and 6.70 - 4.75mm sieve fractions separate.

3.

Discard any sieve fractions which constitute 5 percent or less of the test portion mass, any material retained on a 26.5mm aperture sieve and any material ing a 4.75mm aperture sieve.

4.

Record the mass to at least the nearest 1g, of each of the individual sieve fractions retained for testing.

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Pavements & Structures

5.

TEST METHOD

WA 216.1

If there are: • considerably more than 200 particles for any sieve fraction which contributes more than 15% of the test portion mass, or • considerably more than 100 particles for any sieve fraction which contributes more than 5% but less than 15% of the test portion mass, then those sieve fractions may be reduced by sample division to obtain a test increment of approximately 200 and 100 particles respectively. No attempt shall be made to secure an exact predetermined number. Record the mass of each of the individual test increments.

6.

Test each sieve fraction (or test increment) separately by attempting to each stone manually through the appropriate slot as defined in Table 1. TABLE 1 SLOT GAUGE DIMENSIONS Sieve Fraction 26.50 - 19.00 mm 19.00 - 13.20 mm 13.20 - 9.50 mm 9.50 - 6.70 mm 6.70 - 4.75 mm 4.75 - 2.36 mm

7.

Slot Gauge Markings 26.50 - 19.00 19.00 - 13.20 13.20 - 9.50 9.50 - 6.70 6.70 - 4.75 4.75 - 2.36

Actual Slot Width 13.65 mm 9.66 mm 6.81 mm 4.86 mm 3.44 mm 2.13 mm

Record the mass, to at least the nearest 1g, of the particles ing the appropriate slot for each of the sieve fractions (or test increments) tested.

CALCULATIONS 1.

If the sieve fractions have been reduced, calculate the mass of the particles ing the appropriate slot for each sieve fraction using the formula: E

=

mass of sieve fraction x mass ing slot mass of test increment

where E = mass of particles in sieve fraction that would the appropriate slot 2.

Calculate the Flakiness Index using the formula: Flakiness Index =

MAIN ROADS Western Australia T\WA216-1.doc

ΣMass of Particles ing Slot Gauge x 100 ΣMass of Sieve Fractions Retained for Testing

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Pavements & Structures

TEST METHOD

WA 216.1

REPORTING Report the Flakiness Index to the nearest 0.1 percent. NOTES (a)

If the 16.0mm sieve has been used in the particle size distribution then the 19.0 to 16.0 mm and 16.0 to 13.2mm sieve fractions must be combined to form the 19.0 to 13.2mm sieve fraction.

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Pavements & Structures

TEST METHOD

WA 216.1

FIGURE 1

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Pavements & Structures

TEST METHOD

WA 216.1

APPROXIMATE DIMENSIONS Maximu m size of particle in sample mm 40 20 10 5

Number of slots

8 10 12 12

Internal dimensions mm

A 45 25 13 7

B 150 125 75 38

C 65 38 29 13

This design has been found satisfactory but alternative designs may be employed provided that the essential requirements are f lfill d

FIGURE 2 SUITABLE TYPE OF SAMPLE DIVIDER (RIFFLE BOX)

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