Experiment No: 03
Sieve Analysis of Coarse Aggregate
Introduction
Aggregates, an essential component in construction, are materials like sand, gravel, or crushed stone that are added to cement and water to form concrete. They may be divided into two types: fine and coarse.
Sieve Analysis is a crucial test
method in civil engineering, especially for analyzing aggregates. The process
entails grading aggregates, both fine and coarse, by sieving to determine their
size distribution.
Sieve analysis is a well-established method in the study of materials used to determine the particle size distribution of granular material. This approach is frequently employed across several sectors, with a particular emphasis in construction and civil engineering for analyzing fine and coarse aggregates.
Fineness modulus is only a numerical indicator of fineness giving some sense of the mean size of particles in the entire body of aggregate. Determination of fineness modulus may be viewed as a way of standardizing of the grading of the aggregates. It is achieved by sieving a known mass of specified aggregate on a set of standard sieves and by adding the cumulative percentages of mass of material retained on all the sieves and dividing the total percentage by 100.
Scope
This test method involves the determination of the particle size distribution of course aggregates by sieving.
Purpose
·
To determine the particle size
distribution of course aggregate by sieving
ASTM Designation
·
ASTM C136/C136M-19
·
ASTM C33/C33M-08
Terminology
Aggregate
Granular material, such as sand, gravel, crushed stone, or iron blast-furnace slag, mixed with a cementing medium to make hydraulic-cement concrete or mortar.
Coarse aggregate –
(1)
aggregate mostly retained on the
4.75-mm (No. 4) sieve; or
(2) that fraction of an aggregate remained on the 4.75-mm (No. 4) sieve
Fine aggregate –
(1)
aggregate passing the 9.5-mm
(3⁄8-in.) sieve and basically completely passing the 4.75-mm (No. 4) sieve and
mostly retained on the 75-µm (No. 200) sieve; or
(2) that fraction of an aggregate passing the 4.75-mm (No. 4) sieve and retained on the 75-µm (No. 200) sieve.
Fineness
Modulus of aggregate
·
a factor obtained by adding
the percentages of material in the sample that is coarser than each of the
following sieves (cumulative percentages retained), and dividing the sum by
100.
Significance
This test method is used mainly to determine the grading of materials intended for use as aggregates or being utilized as aggregates. The findings are used to assess compliance of the particle size distribution with applicable specification criteria and to provide essential data for control of the manufacture of various aggregate products and mixtures incorporating aggregates. The data may also be useful in generating correlations relating porosity and packing.
Apparatus
·
Balances or scales with
a minimum accuracy of 0.1 g for fine Aggregate
·
Standard Sieves conforming
to the requirements of Specification ASTMC33
·
Mechanical sieve shaker: The sieving
action shall be such that the criterion for adequacy of sieving is met in
a reasonable time period.
·
Oven capable of maintaining a uniform temperature of 110 ± 5°C [230 ± 10°F]
Sampling
Coarse Aggregate—The size of
the test sample of coarse aggregate shall conform with the following:
|
Nominal Maximum Size, Square Openings, mm (in.) |
Test Sample Size, min, kg [lb] |
|
9.5 (3⁄8) |
1 [2] |
|
12.5 (1⁄2) |
2 [4] |
|
19.0 (3⁄4) |
5 [11] |
|
25.0 (1) |
10 [22] |
|
37.5 (11⁄2) |
15 [33] |
|
50 (2) |
20 [44 |
|
63 (21⁄2) |
35 [77] |
|
75 (3) |
60 [130] |
|
90 (31⁄2) |
100 [220] |
|
100 (4) |
150 [330] |
|
125 (5) |
300 [660] |
Procedure
[1] Dry the sample to
constant mass at a temperature of 110 ± 5 °C [230 ± 10 °F]
[2]
Select sieves with appropriate
apertures to provide the necessary information as stated in the specifications
for the item being tested. Use further sieves as needed to obtain additional
data, including fineness modulus, or to control the quantity of material on a
sieve. Arrange the sieves in descending order of opening size, with the largest
opening at the top, then place the sample on the top sieve. The pan is placed
at the bottommost position. Stir the
sieves manually or with a mechanical device for a certain duration determined
through trial or verified by measuring the actual test sample to ensure it
meets the required standard.
2.1 The
manual method should be performed in a proper sequence which is as follows:
I.
forward and backward motion
II.
left and right motion
III.
clockwise (CW) and counterclockwise
(CCW) motion
IV.
frequent
jolting.
2.2
For mechanical device:
Sieve the material for an adequate
amount of time such that, after finishing, no more than 1% by weight of the
material retained on any one sieve will pass through that sieve in 1 minute of
continuous hand sieving as described. Hold the individual sieve, equipped with
a tight-fitting pan and cover, at a slightly tilted angle with one hand.
Strike the side of the sieve hard and with an upward motion against the heel of
the other hand at a frequency of approximately 150 times per minute, rotating
the sieve roughly one sixth of a rotation every 25 strokes.
[3] Limit the amount of material on a sieve to ensure that all particles have many opportunities to pass through the sieve apertures throughout the sieving process. The amount of material left on a sieve with apertures smaller than 4.75-mm should not be more than 7 kg/m2 of the sieving surface area. The amount of material retained in kilograms on sieves with apertures of 4.75 mm (No. 4) or greater should not exceed 2.5 times the product of the sieve opening in millimeters and the effective sieving area in square meters. In no situation may the quantity retained be so large as to cause forever distortion of the sieve cloth
[4]
Prevent an overload of material on
an individual sieve by one of the following methods:
4.1 Insert an extra sieve with opening size
intermediate between the sieve that may be overloaded and the sieve immediately
above that sieve in the original set of sieves.
4.2 Split the sample into two or more pieces,
sieving each component independently. Combine the masses of the several
portions maintained on a given sieve before computing the percentage of the
sample on the sieve.
4.3 Use sieves with a bigger frame size and
providing greater sieving area.
[5] Determine the mass of each size increment on a scale or balance conforming to the requirements to the nearest 0.1 % of the total original dry sample mass. Compare the total mass of the material after sieving to the initial dry sample mass placed on the sieves. If the quantities vary by more than 0.3 %, based on the original dry sample mass, do not use the data for acceptance purposes.
Calculation
·
Calculate percentages
passing, total percentages retained, or percentages in various size fractions
to the nearest 0.1 % on the basis of the total mass of the initial dry sample.
·
Calculate the fineness
modulus
·
Plot the grain size
distribution on a semi log graph paper
Report
I.
Depending upon the form of the specifications for use of the
material under test, the report shall include the following:
· Total percentage of
material passing each sieve, or
· Total percentage of
material retained on each sieve,
· Percentage of material
retained between consecutive sieves.
II.
Report percentages to the nearest whole number, except if the
percentage passing the 75-µm (No. 200) sieve is less than 10 %, it shall be
reported to the nearest 0.1 %.
III. Report the fineness modulus, when required, to the nearest 0.01
Grading Requirement
The coarse aggregate consists of gravel, crushed gravel, crushed stone, air-cooled blast furnace slag, crushed hydraulic-cement concrete, recycled aggregate, or a mix of these materials, meeting the specification standards.
Grading simply demonstrates the sizes of the aggregates and in which quantities they are present. There are some limitation parameters for every sieve specified by ASTM.
ASTM Grading Requirements for Coarse Aggregates
Coarse aggregates have to satisfy the specifications stated in Table below for the designated size number specified.
|
Size Number |
Nominal
Size (Sieves with Square Openings) |
Amounts Finer than Each Laboratory Sieve (Square-Openings), Mass
Percent |
|||||||||||||||||||||||
|
100 mm (4 in.) |
90 mm (31⁄2
in.) |
75 mm (3 in.) |
63 mm (21⁄2 in.) |
50 mm (2 in.) |
37.5 mm (11⁄2
in.) |
25.0 mm (1 in.) |
19.0 mm (3⁄4
in.) |
12.5 mm (1⁄2
in.) |
9.5 mm (3⁄8
in.) |
4.75 mm (No.
4) |
2.36 mm (No.
8) |
1.18 mm (No.
16) |
300 µm (No.50) |
||||||||||||
|
1 |
90 to 37.5 mm (31⁄2 to 11⁄2
in.) |
100 |
90 to 100 |
... |
25 to 60 |
... |
0 to 15 |
... |
0 to 5 |
... |
... |
... |
... |
... |
... |
||||||||||
|
2 |
63 to 37.5 mm
(21⁄2 to 11⁄2 in.) |
... |
... |
100 |
90 to 100 |
35 to 70 |
0 to 15 |
... |
0 to 5 |
... |
... |
... |
... |
... |
... |
||||||||||
|
3 |
50 to 25.0 mm (2 to 1 in.) |
... |
... |
... |
100 |
90 to 100 |
35 to 70 |
0 to 15 |
... |
0 to 5 |
... |
... |
... |
... |
... |
||||||||||
|
357 |
50 to 4.75 mm (2 in. to No. 4) |
... |
... |
... |
100 |
95 to 100 |
... |
35 to 70 |
... |
10 to 30 |
... |
0 to 5 |
... |
... |
... |
||||||||||
|
4 |
37.5 to 19.0 mm
(11⁄2 to 3⁄4 in.) |
... |
... |
... |
... |
100 |
90 to 100 |
20 to 55 |
0 to 15 |
... |
0 to 5 |
... |
... |
... |
... |
||||||||||
|
467 |
37.5 to 4.75 mm
(11⁄2 in. to No. 4) |
... |
... |
... |
... |
100 |
95 to 100 |
... |
35 to 70 |
... |
10 to 30 |
0 to 5 |
... |
... |
... |
||||||||||
|
5 |
25.0 to 12.5 mm (1 to 1⁄2 in.) |
... |
... |
... |
... |
... |
100 |
90 to 100 |
20 to 55 |
0 to 10 |
0 to 5 |
... |
... |
... |
... |
||||||||||
|
56 |
25.0 to 9.5 mm (1 to 3⁄8 in.) |
... |
... |
... |
... |
... |
100 |
90 to 100 |
40 to 85 |
10 to 40 |
0 to 15 |
0 to 5 |
... |
... |
... |
||||||||||
|
57 |
25.0 to 4.75 mm (1 in. to No. 4) |
... |
... |
... |
... |
... |
100 |
95 to 100 |
... |
25 to 60 |
... |
0 to 10 |
0 to 5 |
... |
... |
||||||||||
|
6 |
19.0 to 9.5 mm (3⁄4 to 3⁄8 in.) |
... |
... |
... |
... |
... |
... |
100 |
90 to 100 |
20 to 55 |
0 to 15 |
0 to 5 |
... |
... |
... |
||||||||||
|
67 |
19.0 to 4.75 mm
(3⁄4 in. to No. 4) |
... |
... |
... |
... |
... |
... |
100 |
90 to 100 |
... |
20 to 55 |
0 to 10 |
0 to 5 |
... |
... |
||||||||||
|
7 |
12.5 to 4.75 mm
(1⁄2 in. to No. 4) |
... |
... |
... |
... |
... |
... |
... |
100 |
90 to 100 |
40 to 70 |
0 to 15 |
0 to 5 |
... |
... |
||||||||||
|
8 |
9.5 to 2.36 mm (3⁄8 in. to No.
8) |
... |
... |
... |
... |
... |
... |
... |
... |
100 |
85 to 100 |
10 to 30 |
0 to 10 |
0 to 5 |
... |
||||||||||
|
89 |
9.5 to 1.18 mm (3⁄8 in. to No.
16) |
... |
... |
... |
... |
... |
... |
... |
... |
100 |
90 to 100 |
20 to 55 |
5 to 30 |
0 to 10 |
0 to 5 |
||||||||||
|
9 |
4.75 to 1.18 mm (No. 4 to No. 16) |
... |
... |
... |
... |
... |
... |
... |
... |
... |
100 |
85 to 100 |
10 to 40 |
0 to 10 |
0 to 5 |
||||||||||
Data sheet
Based on the nominal aggregate size from the table
above
|
Sieve Number |
Sieve Opening (mm) |
Materials Retained
(gm) |
% Materials Retained |
Cumulative % Retained |
% Passing |
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Total |
Σ= |
Σ= |
Calculating % retained =
Percent Passing = (100 – Cumulative percentage retained)
Fineness modulus of fine aggregate =
Gradation chart on a semi log graph paper
Precautions
1. Sieves should be cleaned before use.
2. Stiff worn out brushes should not be used.
3. The sieving must be done carefully to prevent
the spilling of the aggregate.
4.
Do not apply pressure to force the particles through the mesh.
Discussion
……………………
Lab Assignment Questions:
1. Discuss the significance of the cumulative
percentage passing and retained on each sieve in sieve analysis of coarse
aggregate?
2. In what applications or industries is sieve
analysis of coarse aggregate particularly important, and why?
3.
What are
the factors that may influence the accuracy and reliability of sieve analysis
results for coarse aggregate?
4.
What is the
purpose of performing a sieve analysis on a coarse aggregate sample?
5.
Describe
the typical set of sieves used for sieve analysis of coarse aggregate according
to ASTM standards (or any other standard you're familiar with).
6.
How is the
weight of the coarse aggregate sample determined before starting the sieve
analysis?
7.
Explain the
process of sieving the coarse aggregate sample, including the order of sieves
and shaking technique.
8.
How is the
percentage of coarse aggregate retained on each sieve calculated?
9.
What is the
difference between the nominal maximum size and the maximum size of a coarse
aggregate based on a sieve analysis?
10. How can the results of a sieve analysis be
presented graphically? (e.g., graph type)
11. How can the gradation of a coarse aggregate be
described based on the sieve analysis results?
12. What are some factors that can affect the
accuracy of a sieve analysis for coarse aggregate?
13. Briefly explain the concept of fineness modulus
and how it relates to the sieve analysis of coarse aggregate.