DETERMINATION OF TEN PERCENT FINES VALUE OF COARSE AGGREGATE

Test standard: IS 2386 -Part IV: 1963

Purpose of Test:

Ten percent fines value is a measure of the resistance of aggregate crushing subjected to loading and it is applicable to both weak and strong aggregate.

Test Procedure :

1. Take a representative quantity of the sample of aggregate by quartering method.
2. Test sample prepared by passing the aggregate from 12.5mm IS Sieve and retained on 10mm IS Sieve. Test sample shall be tested in SSD Condition.
3. Fill the sample in a cylindrical metal measure in three layers with 25 number of tamping in each layer. The third layer/top layer shall be overfilled & surplus aggregates shall be struck off using tamping rod.
4. The quantity of aggregate shall be such that the depth of material in the cylinder after tamping shall be 10cm. The net weight of the test sample in the measure shall be determined to nearest 1.0 gms (say W1, gms)
5. The cylinder of the apparatus shall be put in position on base plate & the test sample shall be added in three layers with 25numbers of strokes from tamping rod in each layer. Surface of the aggregate shall be levelled & the plunger inserted so that it rests horizontally on this surface.
6. The apparatus with test sample & plunger shall be placed in compression testing machine.
7. The load shall be uniformly applied so as to cause a total penetration of plunger in 10 minutes.
8. After reaching the maximum penetration, load shall be released & its value shall be recorded (say X, Ton). Test sample shall be removed from the cylinder & sieved over 2.36mm IS Sieve & the fines passing the sieve shall be weighed (say W2, gms).

Penetration Value of plunger in 10 minutes:

• 15.0 mm for rounded or partially rounded aggregates
• 20.0 mm for normal crushed aggregates
• 24.0 mm for honeycombed aggregates

 Result Calculation:

Ten percent fines value (%)  = (W2/W1) x 100

Which shall fall between 7.5 to 12.5 %
If not a repeat shall be made with adjusted load to bring the fines within the range of 7.5 to 15.0 percent. 
The mean percentage fines from the two tests (say Y %) at this load shall be used in the formula to calculate the load required to give 10% fines: Y+4

Load required for 10% fines = 14 x X

The load required for 10% fines shall be reported to the nearest whole number of loads of 10T or more & nearest 0.5T for less than 10T

Read more :

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