Objective

For determination of the quantity of material finer than 75 micron IS sieve in aggregates by washing. 

Reference Standards

IS : 2386 (Part I) – 1963 – Method of test for aggregates for concrete (Part I) Particle size and shape.

Equipment & Apparatus

• Balance (0-10 kg)
• Sieves (1.18 mm,75 micron)
• Oven (300⁰c)
• Container 

Preparation sample

Sample required for the test is as per table below.

MAXIMUM NOMINAL SIZE OF AGGREGATE (mm)	APPROXIMATE MINIMUM WEIGHT OF SAMPLE (g)
4.75	500
10.0	2000
20.0	2500
40 or over	5000

Procedure

1. The sample is dried to constant mass in the oven at a temperature of 110⁰±5⁰C.
2. After drying the test sample is placed in a container with sufficient water to cover the test sample, and is agitated vigorously to separate all the fine particles from the coarse particles
3. Then the entire test sample with water is poured over the nested sieves arranged with coarser sieve on the top and 75micron sieve at the bottom, and is washed under running water until wash water is clear.
4. All the material retained on the nested sieve is returned to the washed sample and is dried to constant weight at a temperature of not exceeding 110⁰C. 

Calculation

The amount of material passing 75 micron IS sieve is calculated as follows

A = Percentage of material finer than 75 micron

B = Original dry weight

C = Dry weight after washing 

Report

Materials finer than 75 micron is reported in percentage to the nearest 0.5%.

Safety & Precautions

• Use hand gloves while removing containers from oven after switching off the oven.
• Use safety shoes, mask & aprons at the time of test.
• Thoroughly clean & dry the container before testing.
• Special care should be taken that no outer air enters when using the balance.
• After test sieve should be clean by a soft brush.