Lab Test on Aggregates - Sieve Analysis for Materials finer than 75 Micron

TEST FOR AGGREGATES FOR CONCRETE

IS 2386-1 (1963): Methods of Test for Aggregates for Concrete, Part I: Particle Size and Shape [CED 2: Cement and Concrete]

SIEVE ANALYSIS - DETERMINATION OF MATERIALS FINER THAN 75-MICRON

Object - This method of test deals with the procedure for determining the total quantity of material finer than 75micron IS Sieve in aggregates by washing.

Apparatus

Sieves - A nest of two sieves, the lower being 75-micron IS Sieve and the upper approximately l-18-mm IS Sieve [see IS : 460-1962 Specification for Test Sieves

Container - A nest of two sieves, the lower being 75-micron IS Sieve and the upper approximately l-18-mm IS Sieve [see IS : 460-1962 Specification for Test Sieves

Oven - A pan or vessel of a size sufficient to contain the sample covered with water and to permit of vigorous agitation without inadvertent loss of any part of the sample or water.

Balance - The balance or scale shall be of sufficient capacity and sensitivity and shall have an accuracy of 0.1 percent of the weight of the test sample.

Sample - The weight of sample available shall be not less than the weight given in Table below. The sample for sieving shall be prepared from the larger sample either by quartering or by means of a sample divider.

MINIMUM WEIGHTS FOR SAMPLING

MAXIMUM SIZE PRESENT IN SUBSTANTIAL PROPORTIONS	MINIMUM WEIGHT OF SAMPLE DESPATCHED FOR TESTING
mm	kg
4.75	500
10	2000
20	2500
40 or over	5000

Test Procedure

The test sample shall be dried to constant weight at a temperature of 110^o+5^oC and weighed to the nearest 0.1 percent.

The test sample after being dried and weighed shall be placed in the container and sufficient water added to cover it. The contents of the container shall be agitated vigorously.

The agitation shall be sufficiently vigorous to result in the complete separation from the coarse particles of all particles finer than 75-micron and bring the fine material into suspension. Care shall be taken to avoid, as much as possible, the decantation of the coarse particles of the sample. The operation shall be repeated until the wash water is clear.

The wash water containing the suspended and dissolved solids shall be immediately poured over the nested sieves arranged with the coarser sieve on the top.

All material retained on the nested sieves shall be returned to the washed sample. The washed aggregate shall be dried to constant weight at a temperature not exceeding 110°C and weighed to the nearest 0.1 percent.

Calculation:

The amount of material passing the 75-micron IS Sieve shall be calculated as follows:

A= (B-C)/B}x100

where A = percentage of material finer than 75-micron,

B = original dry weight, and

C = dry weight after washing.