sieve analysis

Mechanical Analysis of Soil

Mechanical analysis is the determination of the size range of particles present in a soil, expressed as a percentage of the total dry weight.

There are two methods generally used to find the particle–size distribution of soil:

1) sieve analysis – for particle sizes larger than 0.075 mm in diameter, and

(2) hydrometer analysis – for particle sizes smaller than 0.075 mm in diameter. The basic principles of sieve analysis and hydrometer ever analysis are briefly described in the following two sections.


Sieve analysis Hydrometer analysis

Sieve Analysis

Sieve analysis consists of shaking the soil sample through a set of sieves that have progressively smaller openings.

Sieve Analysis

Sieve Number Opening (mm)4 4.7506 3.3508 2.36010 2.00016 1.18020 0.85030 0.60040 0.42550 0.30060 0.25080 0.180100 0.150140 0.106170 0.088200 0.075270 0.053

Sieve Analysis

First the soil is oven dried and then all lumps are broken into small particle before they are passed through the sieves

After the completion of the shaking period the mass of soil retained on each sieve is determined

Sieve Analysis

The results of sieve analysis are generally expressed in terms of the percentage of the total weight of soil that passed through different sieves

Sieve#

Diameter(mm)

Mass of soilretained

on each sieve(g)

Percent ofsoil

retained oneach sieve (g)

Percentpassing

(%)

10 2.000 0 0 100.0016 1.180 9.90 2.20 97.8030 0.600 24.66 5.48 92.3240 0.425 17.60 3.91 88.4160 0.250 23.90 5.31 83.10100 0.150 35.10 7.80 75.30200 0.075 59.85 13.30 62.00Pan –– 278.99 62.00 0

CIVL 1101 Introduction to Sieve Analysis 1/6

Sieve Analysis

Sieve#

Diameter(mm)


on each sieve(g)

Percent ofsoil


Percentpassing

(%)

10 2.000 0 0 100.0016 1.180 9.90 2.20 97.8030 0.600 24.66 5.48 92.3240 0.425 17.60 3.91 88.4160 0.250 23.90 5.31 83.10100 0.150 35.10 7.80 75.30200 0.075 59.85 13.30 62.00Pan –– 278.99 62.00 0

Sieve Analysis (Mass of Dry Soil Sample = 450 g)

Sieve Analysis

Sieve#

Diameter(mm)


on each sieve(g)

Percent ofsoil


Percentpassing

(%)

10 2.000 0 0 100.0016 1.180 9.90 2.20 97.8030 0.600 24.66 5.48 92.3240 0.425 17.60 3.91 88.4160 0.250 23.90 5.31 83.10100 0.150 35.10 7.80 75.30200 0.075 59.85 13.30 62.00Pan –– 278.99 62.00 0

Sieve Analysis (Mass of Dry Soil Sample = 450 g)

Particle–Size Distribution Curve

The results of mechanical analysis (sieve and hydrometer analyses) are generally presented by semi–logarithmic plots known as particle–size distribution curves.

The particle diameters are plotted in log scale, and the corresponding percent finer in arithmetic scale.

Particle–Size Distribution Curve

Silt and claySand

Particle diameter (mm)

Perc

ent

fine

r (%

)

1. Weigh to 0.1 g each sieve which is to be used2. Select with care a test sample which is representative

of the soil to be tested3. Weigh to 0.1 a specimen of approximately 500 g

of oven–dried soil4. Sieve the soil through a nest of sieves by hand

shaking. At least 10 minutes of hand sieving is desirable for soils with small particles.

5. Weigh to 0.1 g each sieve and the pan with the soil retained on them.

6. Subtract the weights obtained in step 1 from those of step 5 to give the weight of soil retained on each sieve.

The sum of these retained weights should be checked against the original soil weight.

Recommended Procedure

Percentage retained on any sieve:

Calculations

100%weight of soil retainedtotal soil weight

= ×

Cumulative percentage retained on any sieve:

Percentage retained= ∑

Percentage finer than an sieve size:

100% Percentage retained− ∑


Effective Size, Uniformity Coefficient, and Coefficient of Gradation

Three basic soil parameters can be determined from these grain–size distribution curves:

Effective size

Uniformity coefficient

Coefficient of gradation

The diameter in the particle–size distribution curve corresponding to 10% finer is defined as the effective size, or D10.


Perc

ent

fine

r (%

)


D10 = 0.093 mm


The uniformity coefficient is given by the relation:

60

10u

DCD

=

Where D60 is the diameter corresponding to 60% finer in the particle-size distribution


Perc

ent

fine

r (%

)


D60 = 0.51 mm


The coefficient of gradation may he expressed as:2

30

10 60c

DCD D

=×

Where D30 is the diameter corresponding to 30% finer in the particle-size distribution


Perc

ent

fine

r (%

)Effective Size, Uniformity Coefficient, and

Coefficient of Gradation

D30 = 0.25 mm



For the particle-size distribution curve we just used, the values of D10, D30, and D60 are:

D10 = 0.093 mm D30 = 0.25 mm D60 = 0.51 mm

60

10u

DCD

= 0.51 5.50.093

mmmm

= =

230

10 60c

DCD D

=×

2(0.25 ) 1.30.51 0.093

mmmm mm

= =×



Perc

ent

fine

r (%

)

The particle–size distribution curve shows not only the range of particle sizes present in a soil but also the type of distribution of various size particles.



Perc

ent

fine

r (%

)

This particle-size distribution represents a soil in which the particles are distributed over a wide range, termed well graded



Perc

ent

fine

r (%

)

This particle-size distribution represents a type of soil in which most of the soil grains are the same size. This is called a uniformly graded soil.



Perc

ent

fine

r (%

)

This particle-size distribution represents such a soil. This type of soil is termed gap graded.

Example Sieve Analysis

From the results of a sieve analysis, shown below, determine:

(a) the percent finer than each sieve and plot a grain–sizedistribution curve,

(b) D10, D30, D60 from the grain–size distribution curve,

(c) the uniformity coefficient, Cu, and

(d) the coefficient of gradation, Cc.

SieveNumber

Diameter(mm)

Mass of soil retainedon each sieve (g)

4 4.750 2810 2.000 4220 0.850 4840 0.425 12860 0.250 221100 0.150 86200 0.075 40Pan –– 24



SieveNumber

Diameter(mm)


4 4.750 2810 2.000 4220 0.850 4840 0.425 12860 0.250 221100 0.150 86200 0.075 40Pan –– 24

SieveNumber


on each sieve(g)

Percentretainedon each

sieve (%)

Cumulativepercent

retained on eachsieve (%)

Percentfiner (%)

4 28 4.54 4.54 95.4610 42 6.81 11.35 88.6520 48 7.78 19.13 80.8740 128 20.75 39.88 60.1260 221 35.82 75.70 24.30100 86 19.93 89.63 10.37200 40 6.48 96.11 3.89Pan 24 3.89 100.00 0

617


SieveNumber


on each sieve(g)


sieve (%)

Cumulativepercent


Percentfiner (%)

4 28 4.54 4.54 95.4610 42 6.81 11.35 88.6520 48 7.78 19.13 80.8740 128 20.75 39.88 60.1260 221 35.82 75.70 24.30100 86 19.93 89.63 10.37200 40 6.48 96.11 3.89Pan 24 3.89 100.00 0

617



Perc

ent

fine

r (%

)


D30 = 0.27 mm

D10 = 0.14 mm

D60 = 0.42 mm



D10 = 0.14 mm D30 = 0.27 mm D60 = 0.42 mm

60

10u

DCD

= 0.42 3.00.14

mmmm

= =

230

10 60c

DCD D

=×

2(0.27 ) 1.20.42 0.14

mmmm mm

= =×

Group Work - Sieve Analysis

From the results of a sieve analysis, shown below, determine:

(a) the percent finer than each sieve and plot a grain–sizedistribution curve,

(b) D10, D30, D60 from the grain–size distribution curve,

(c) the uniformity coefficient, Cu, and

(d) the coefficient of gradation, Cc.

SieveNumber


4 010 4020 6040 8960 14080 122100 210200 56Pan 12



SieveNumber


on each sieve(g)


sieve (%)

Cumulativepercent


Percentfiner (%)

4 010 4020 6040 8960 14080 122100 210200 56Pan 12

729


SieveNumber


on each sieve(g)


sieve (%)

Cumulativepercent


Percentfiner (%)

4 0 0 0 100.010 40 5.5 5.5 94.520 60 8.2 13.7 86.340 89 12.2 25.9 74.160 140 19.2 45.1 54.980 122 16.7 61.8 38.2100 210 28.8 90.6 9.4200 56 7.7 98.3 1.7Pan 12 1.6 99.9 0.1

729


Perc

ent

fine

r (%

)


D30 = 0.17 mm

D10 = 0.15 mm

D60 = 0.28 mm



D10 = 0.15 mm D30 = 0.17 mm D60 = 0.28 mm

60

10u

DCD

= 0.28 1.90.15

mmmm

= =

230

10 60c

DCD D

=×

2(0.17 ) 0.690.28 0.15

mmmm mm

= =×


Any Questions?


Perc

ent

fine

r (%

)


sieve analysis

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