Objective

For determination of the aggregates 10% fines value of coarse aggregate, which passes 12.5 mm. IS sieve and retained on 10 mm IS sieve 

Reference Standards

IS : 2386 (Part IV)-1963  Methods of test for aggregate for concrete  Part IV Mechanical Properties.

Equipment & Apparatus

• Steel cylinder
• Sieves (12.5mm,10mm)
• Cylindrical metal measure
• Tamping Rod
• Balance (0-10kg)
• Oven (300⁰c)
• Compression testing machine 

Preparation sample

Test sample is dried in oven for a period of four hours at a temperature of 100 to 110⁰C. 

Procedure

1. The cylindrical measure is filled by the test sample of aggregate in three layers of approximately equal depth, each layer being tamped 25 times.
2. The test sample in the cylinder with the plunger in position is placed in the compression testing machine. The load is applied at a uniform rate so as to cause a total penetration of the plunger of about 20mm for normal crushed aggregates in 10 minutes.
3. For rounded or partially rounded aggregates, the load required to cause a total penetration of 15mm is applied where as for honeycombed aggregates a penetration of 24mm is applied in 10 minutes.
4. After the maximum specified load is reached, the load is released and the aggregate from the cylinder is sieved from 2.36mm IS sieve.
5. The fines passing 2.36mm.IS sieve is weighed and expressed as a percentage of by weight of the test sample. 

Calculation

The mean percentage fines from the two tests at this load shall be used in the following formula to calculate the load required to give 10% fines.

Load required for 10% fines = 14x / (y + 4)

x = load in tones

y = mean percentage fines from two tests at x tone load.

Report

The load required to produce 10% fines is reported to the nearest whole number for loads of 10 tones or more, the nearest 0.5 tones for loads of less than 10 tones. 

Safety & Precautions

• Use hand gloves while removing containers from oven after switching off the oven.
• Use safety shoes & aprons at the time of test.
• Before testing machine should be checked.
• After test electric supply should be off.
• Thoroughly clean & dry the container before testing.
• All parts of the equipments should always be clean.