SIEVE ANALYSIS



SIEVE ANALYSIS OF FINE AND COARSE AGGREGATES

IS: 2386 - Part I

1. Introduction

This method covers the procedure to determine the gradation of fine and coarse aggregates by sieving.

2. Apparatus

(i) IS sieves required for the specified grading or purpose.

(ii) A mechanical sieving device is recommended if the sample size is more than 20 kg and may be used for even smaller samples.

(iii) A balance of suitable capacity readable to 0.1 percent of the mass.

(iv) A thermostatically controlled oven capable of maintaining temperatures of 110±5oC

3. Sample size

The recommended mass of coarse aggregate samples to be collected shall be as given in the table below

Nominal maximum size mm Minimum mass of sample kg
6.3 3
10 6
12.5 12
16 25
20 25
25 50
40 50
50 100
63 100
75 100
90 100
100 150
125 300

 The sample is thoroughly mixed and reduced to the amount required for testing. The reduction of the sample to the exact predetermined mass is not permitted.  The minimum test sample of fine aggregates after drying shall be 300 gm. 

4. Procedure for coarse and fine aggregates 

a) Dry the test sample to a constant mass and air dry condition at a temperature of 110±5 oC.

b) Clean the selected sieves.

c) Arrange the sieves in the sieve shaker in such a way that largest size sieve is at the top.

d) Always ensure that the bottom pan is not omitted.

e) Mechanical sieving using a sieve shaker shall be done for a minimum period of ten minutes.

f) In the case of manual sieving, each sieve shall be shaken separately for minimum two minutes

g) The shaking shall be done in varied motion so that the material continuously moves over the sieve surface.

h) Material shall not be forced by pressure except for particle size more than 20 mm where placing by hand is permitted.

i) Lumps of fine materials may be broken by pushing to the side of the sieves with fingers.

j) A soft brush can be used to brush underside of the sieve to clear the openings.

k)  For 150 and 75 micron sieves, fine camel hair brush shall be used to push the materials down, without applying any pressure

 l) On completion of sieving, the material retained in each sieve is taken out and weighed accurately.

m) Overloading of the test sieves should be avoided. After completion of sieving, the weight retained in sieves shall not exceed the weights given below.  

  Coarse aggregates Fine aggregates
IS sieve Maximum weight in Maximum weight Maximum weight
  45 cm dia sieves    
50 mm 10 kg 4.5 kg -
40 mm 8 kg 3.5 kg -
31.5/25 mm 6 kg 5.5 kg -
20 mm 4 kg 2.0 kg -
16/12.5 mm 3 kg 1.5 kg -
10 mm 2 kg 1.0 kg -
6.3 mm 1.5 kg 0.75 kg -
4.75 mm 1.0 kg 0.50 kg -
3.35 mm - 0.30 kg -
2.36 mm - - 200 gm
1.18 mm - - 100 gm
600 micron - - 75 gm
300 micron - - 50 gm
150 micron - - 40 gm
75 micron - - 25 gm

5. Procedure for sieving fine and coarse aggregate mix

The weight of sample for testing shall be as given below, prepared from large samples collected from stockpile

IS sieve designation Minimum weight of sample for sieve analysis
63 mm 50 kg
50 mm 35 kg
40/31.5 mm 15 kg
25 mm 5 kg
20/16 mm 2 kg
12.5 mm 1 kg
10 mm 500 gm
6.3 mm 200 gm
4.75 mm 200 gm
2.36 mm 100 gm

To avoid heavy loading of the sieves, the test shall be carried out by splitting the sample into several parts. Also the aggregate mix shall be initially separated into coarse and fine aggregates using a 3.35 mm or 4.75 mm sieve before sieving is commenced. 

6. Calculations

The cumulative percentage passing by weight for each sieve is determined and reported to the nearest whole number. For material retained the weight is recorded to the nearest 0.1 gm. The results of the sieve analysis shall be also represented in a graphical method, with cumulative percentage passing on the Y-axis expressed linearly and sieve diameter on the X-axis plotted in a logarithmic scale.  A sample format for recoding the sieve analysis data is attached for guidance. 

AMOUNT OF FINES PASSING 75 MICRON SIEVE BY WET SIEVING 

IS: 2386 - Part I

1. Introduction

Materials finer than 75 mic (No. 200) can be separated from larger particles much more efficiently and completely by wet sieving. When accurate determination of such fraction in the aggregate is required, this method is used prior to dry sieving. Plain water is adequate for washing. Dispersing agents like liquid dish washing detergents may be used if clay coatings and coatings on extracted aggregate are to be removed.

2. Apparatus

(i) A balance of suitable capacity with accuracy of 0.1 percent of the test sample.

(ii) IS test sieves 75 mic and 1.18 mm.

(iii) A container or pan to soak the sample and of size large enough to agitate the soaked material without loss of water or sample

(iv) A thermostatically controlled oven capable of maintaining temperatures of 110±5oC.

(v) Wetting agent etc.

3. Sample preparation

The test sample shall be prepared from thoroughly mixed material containing sufficient moisture to prevent segregation. The weight of test sample shall be as given in the table below.   

Nominal maximum size Minimum mass of test
mm sample gm
4.75 500
10 2000
20 2500
40 or above 5000

4. Procedure using water for washing

a) Dry the sample to constant weight at 110±5oC and find the weight (A) after cooling.

b) Place the sample in the container, pour water and agitate the sample vigorously to separate the fine particles from the coarse particles.

c) Immediately pour the wash water over the sieves arranged with the coarser sieve the top.

d) Add similar increments of water to the aggregate in the container and repeat the process till the wash water is clean.

e) Rinse the sieves with a spray nozzle or a small hose.

f) Return all materials retained on the sieves to the washed sample in the container.

g) Dry the washed aggregate in the container to constant weight (B) in the oven at a temperature not exceeding 110oC.

NOTE: Use of mechanical apparatus for washing is not recommended. 

5. Procedure using a wetting agent for washing

a) After drying and determining the weight place the test sample in a container.

b) Add sufficient water to cover the sample and add the wetting agent.

c) Agitate the sample vigorously to separate the fine particles from the coarse particles.

d) Immediately pour the wash water over the sieves arranged with the coarser sieve the top.

e) Add another charge of water without wetting agent and repeat the process.  

f) Continue till the wash water is clean.

g) Dry the washed aggregate in oven and find the weight. 

6. Calculation Calculate the amount of material passing 75 micron sieve from the equation:

[(A-B)/A] x 100, where  A = Original dry weight of the sample in gm.  

B = Dry weight in gm after washing.

Report the percentage of material finer than 75 mic sieve by washing to the nearest 0.1 percent.

DETERMINATION OF BULK DENSITY AND VOIDS OF AGGREGATES 

IS: 2386 - Part III 

1. Introduction

This method of test is prescribed to determine the bulk density (Unit weight) and voids of aggregates. Unit weight is the traditional terminology used to describe the property which is weight per unit volume (More precisely, mass per unit volume). The bulk density of the aggregate determined by this procedure is measured in kilograms per litre.  This test is intended to compare the properties of different aggregates. It is not generally suitable for use as a basis for quoting mix design conversion factors. 

2. Apparatus

(i) A cylindrical metal measure with handle. It shall be watertight, with sufficient rigidity for rough use. The capacity required for the different sizes of aggregates are given in the table below

Table 1: Sizes of containers for bulk density test 

Size of largest particles Nominal capacity (in litres) Inner dia in cm Inside height in cm Wall thicknessin mm 
4.75 mm or less 3 15 17 3.15
4.75 mm to 40 mm 15 25 30 4
More than 40 mm 30 35 51 5

(ii) A balance of suitable capacity sensitive to 0.5% of the weight of the sample to be weighed.

(iii) A straight metal tamping rod of cylindrical cross-section, 16 mm in diameter and 60 cm long, rounded at one end

3. Calibration of the container

The measure shall be calibrated by determining the weight of water at 27°C required to fill it such that no meniscus is present above the rim of the container. The capacity in litres shall be obtained by dividing the weight of water in kilograms required to fill the container at 27°C by the weight of water in one litre at 27°C, which may be taken as one kilogram.

4. Procedure

Dry material shall be used for determining the voids. Material with the given percentage of water shall be chosen while determining bulking of aggregates.

4.1 Procedure by rodded or compacted weight

a) Fill the measure one-third with thoroughly mixed test sample.

b) Tamp the layer of aggregate 25 times with the round end of the tamping rod ensuring the strokes evenly distributed over the surface. Do not allow the tamping rod to touch the bottom of the measure.

c) Fill the measure up to two thirds full and tamp again 25 times vigorously but without penetrating the layer below.  

d) Fill the measure overflowing and tamp 25 times vigorously. Level the surface with a straight edge in such a way that the projections of aggregate balance with the larger voids on the aggregate surface.

e) Determine the mass of the measure plus contents. Determine the empty weight of the measure. Calculate the bulk density of the aggregate from the weight of aggregate and volume of the measure determined earlier

4.2 Procedure by loose weight

a) Fill the measure to over flowing using a shovel or scoop. Discharge the aggregates from a height of 50mm above the top edge of the measure exercising enough care to prevent segregation of the particles.

b) Level the surface with straight edge in such a way that the projections of aggregate balance with the larger voids on the aggregate surface.

c) Determine the mass of the measure plus contents and measure alone and record in kilogram per liter.

d) Determine the mass of the measure plus contents. Determine the empty weight of the measure. Calculate the bulk density of the aggregate from the weight of aggregate and volume of the measure determined earlier.

5. Calculation

a) Calculate the bulk density of the aggregates as below:

Bulk Density,= [M2-M1]/V in kg/liter where

M2= Weight of the aggregate plus measure in kg  

M1= Weight of the measure in kg and

V= Volume of the measure in liter obtained from calibration If the volume V is expressed in m3, the bulk density can be obtained in kg/m3.

b) The percentage of voids shall be calculated as follows:

Percentage of voids = [Gs] / Gs x 100  

Gs = Specific gravity of the aggregate an

 Bulk density in kg/litre.

6. Report

The report shall include the following:

(i) The bulk density shall be reported in kg/litre or kg/m3 to the nearest 0.01 kg.

(ii) The voids shall be reported as a percentage to the nearest whole number.

(iii) The condition of aggregate at the time of test shall be stated, that is (a) oven dry (b) saturated and surface dry or (c) with a given percentage of moisture. 

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