50 INDIAN GEOTECHNICAL CONFERENCE 50 17 19 DECEMBER …igs/ldh/files/igc 2015 pune/THEME 14... · 2017-05-14 · 50 th 50th INDIAN GEOTECHNICAL CONFERENCE 17 th–19 DECEMBER 2015,

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50th INDIAN GEOTECHNICAL CONFERENCE

17th – 19th DECEMBER 2015, Pune, Maharashtra, India

Venue: College of Engineering (Estd. 1854), Pune, India

COMPACTION CHARACTERISTICS OF FINE-GRAINED SOILS WITH VARYING

ENERGY LEVELS

Dr.H.S.Prasanna1, Ammalu Padmakumar2, Likith.S3, Chaitra.C.D4, Akishe.S.Jimomi5

ABSTRACT

Soil compaction is one of the most important and routine engineering techniques performed to assure the

safety and stability of soils. Compacted soil is required for constructing highways, airways, earth

retaining structures, etc. The study of compacted soils become very important in the present day scenario

wherein the lack of good construction sites is forcing people to go for sites which have been considered

unsuitable for construction works.

Compaction is a kind of densification done by mechanical rearrangement of soil particles without outflow

of water. Here, soil particles are rearranged and packed together in a closer state of contact thus

decreasing the porosity of soil and increasing its dry density.

While the compaction of coarse-grained soils do not pose problem to a field engineer, the same is not true

about the compaction of fine-grained soils. While the compaction of coarse-grained soil is purely a

physical problem, the behaviour of compacted fine-grained soils is expected to be physio-chemical in

nature by virtue of the clay mineralogical composition of such soils. Thus, compaction of fine-grained

soils is gaining importance because of its contradictory behaviour with respect to clay mineralogy.

It is also understood that many man made structures necessitates impounding of higher compactive

energy levels owing to its service requirements like road, railway embankments subjected to heavy axle

loads, and rolling loads, runways and taxiways in major airports, docks and harbours etc. Hence, it is

necessary to understand the role of compactive energy levels (Standard Proctor, Modified Proctor)

involved in the process and the clay mineralogical behaviour of the said soils. Also, the importance of

1Compaction characteristics of fine-grained soils with varying energy levels_Dr.H.S.Prasanna, Professor Civil Engineering

Department, NIE, Mysore, India, [email protected] 2Compaction characteristics of fine-grained soils with varying energy levels_Ammalu Padmakumar, Student, NIE, Mysore,

India, [email protected] 3Compaction characteristics of fine-grained soils with varying energy levels_Likith.S., Student, NIE, Mysore, India,

[email protected] 4Compaction characteristics of fine-grained soils with varying energy levels_Chaitra.C.D, Student, NIE, Mysore, India,

[email protected] 5Compaction characteristics of fine-grained soils with varying energy levels_Akishe.S.Jimomi, Student, NIE, Mysore, India,

[email protected]

mailto:[email protected]





Dr.H.S.Prasanna, Ammalu Padmakumar, Likith.S, Chaitra.C.D & Akishe.S.Jimomi

Reduced Standard Proctor and Reduced Modified Proctor (which requires sixty percent of energy levels

of Standard Proctor and Modified Proctor respectively) qualifies in the study.

It is reported in literature that liquid limit of soil is having a definite relationship with compaction

characteristics of soil (Pandian et al 1997). It is also reported that plastic limit of soil can be correlated

effectively with compaction characteristics of soil: Nagaraj (2000), Gurtug and Sridharan (2004),

Sridharan and Nagaraj (2005).

In the present experimental work, six field soils having different clay mineralogical compositions has

been selected in nd around Mysuru and Chamarajnagar District, Karnataka. An attempt has been made to

establish the correlation between liquid limit, plastic limit, plasticity index, shrinkage limit of soils with

compaction characteristics of soils having different clay mineralogy altogether. An attempt has also been

made to correlate index properties of soils with compaction characteristics of soils for varying energy

levels. The results obtained in documented literature have been compared with the results obtained from

present experimental work.

It is observed that compaction characteristics of fine-grained soils irrespective of clay mineralogy can be

related more effectively with plastic limit, shrinkage limit and shrinkage index in relative comparison to

liquid limit and plasticity index which highlights that the liquid limit of soils is not the only criteria for

correlating compaction characteristics with index properties of soils. The results indicate that there is a

good correlation between maximum unit weights and optimum moisture contents irrespective of

compaction energy levels and clay mineralogy.

Keywords: clay mineralogy, compaction, compaction energy, fine-grained soils, index properties

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COMPACTION CHARACTERISTICS OF FINE-GRAINED SOILS WITH

VARYING ENERGY LEVELS

Dr.H.S.Prasanna1 , Professor, NIE, Mysuru, [email protected]

Ammalu Padmakumar2 , Student, NIE, Mysuru, [email protected]

S Likith3 , Student, NIE, Mysuru, [email protected]

C D Chaitra4 , Student, NIE, Mysuru, [email protected]

Akishe S Jimomi5 , Student, NIE, Mysuru, [email protected]

ABSTRACT: In the present experimental work, an attempt has been made to establish the correlation between

liquid limit, plastic limit, plasticity index, shrinkage limit of soils with compaction characteristics of soils having

different clay mineralogy altogether. An attempt has also been made to correlate index properties of soils with

compaction characteristics of soils for varying energy levels. It is observed that compaction characteristics of fine-

grained soils irrespective of clay mineralogy can be related more effectively with plastic limit, shrinkage limit and

shrinkage index in relative comparison to liquid limit and plasticity index. The results indicate that there is a good

correlation between maximum unit weights and optimum moisture contents irrespective of compaction energy

levels and clay mineralogy.

INTRODUCTION

Modification of soils to improve their engineering

properties to the optimum levels at the site plays a

major role in practical situations. Well-compacted

soils increase the performance of the soil by

improving its shear strength and resistance to

settlement behaviour. The compaction

characteristics of any soil are optimum moisture

content (OMC) and maximum dry density (MDD).

Thus, the behaviour of the coarse-gained soils and

fine-grained soils are entirely different altogether.

The effort of compaction imparts changes in some

desirable properties of the soil, such as reduction of

compressibility, water absorption and permeability,

increase in soil strength, bearing capacity etc and

change in swelling and shrinkage characteristics. It

also influences the change in structure of soil,

shear strength and pore pressure.

Based on clay mineralogy, the soils are classified

as K-soil, M-soil or K-M-soil. Compaction

behaviour of K-soils and M-soils are different

altogether. It is difficult to find soils having purely

kaolinite or montmorillonite clay mineral. Most

soils consist of different clay minerals like

kaolinite or montmorillonite in different

proportions. Due to the presence of kaolinite clay

mineral, attractive forces dominate whereas in

montmorillonite it is dispersive in effect. Hence,

the presence of kaolinite and montmorillonite in

equal proportions might have different effect as it

neutralises the forces and affect compaction

characteristics.

In the present experimental work, an attempt has

been made to establish the correlation between

liquid limit, plastic limit, plasticity index,

shrinkage limit & shrinkage index of soils with

compaction characteristics of soils having different

clay mineralogy altogether and varying compaction

energy levels.







Theory of Compaction

Relationship between the Maximum dry density

and the optimum moisture content is very

important when compaction characteristics are

involved. Investigators like Proctor [1],

Hogentolger [2], Hilf [3], Olson [4], Barden &

Sides [5], Nagaraj & Srinivasmurthy [6] have

attempted to explain the shape of the curve of

OMC v/s MDD for fine-grained soils.

Gens [7] observed that the compaction procedure

such as compaction water content and the

compactive effort are known to have a significant

influence on the subsequent mechanical behavior

of compacted cohesive soils. Pandian et al. [8] have

proposed a method to predict the compaction

characteristics in terms of the liquid limit.

Sridharan & Nagaraj [9] concluded that the

shrinkage index (liquid limit-shrinkage limit)

correlates better to the compaction characteristics

than plasticity index or the liquid limit of soils.

Gurtug and Sridharan [10] gave the relationships

and modifications of Standard Proctor and

Modified Proctor. The study of Sridharan &

Nagaraj [11] shows that liquid limit or plasticity

index don't correlate well with the compaction

characteristics of fine-grained soils.

Effect of Compaction characteristics on Energy

Levels and Index Properties

Shivakumar & Wheeler [12] reported that change

in OMC produces radical effect on soil behavior.

Gurtug & Sridharan [10] studied the compaction

behavior & characteristics of fine-grained soils

with reference to compaction energy. They

reported that the index properties namely plastic

limit can be better related to the compaction

characteristics of the fine-grained soils for varying

energy levels like Standard Proctor (SP), Reduced

Standard Proctor (RSP), Modified Proctor (MP)

and Reduced Modified Proctor (RMP) in relative

comparison to liquid limit and plasticity index and

established the relations as shown below.

𝑅𝑆𝑃: 𝑂𝑀𝐶 = 1.0 ∗ 𝑊𝑝 (1)

𝑆𝑃: 𝑂𝑀𝐶 = 0.92 ∗ 𝑊𝑝 (2)

𝑅𝑀𝑃: 𝑂𝑀𝐶 = 0.7 ∗ 𝑊𝑝 (3)

𝑀𝑃: 𝑂𝑀𝐶 = 0.7 ∗ 𝑊𝑝 (4) The relationships between γd max and OMC for

various compactions energy levels are:

𝑅𝑆𝑃: 𝛾𝑑 𝑚𝑎𝑥 = 22.42 − 0.30 𝑂𝑀𝐶 (5) 𝑆𝑃: 𝛾𝑑 𝑚𝑎𝑥 = 21.61 − 0.26 𝑂𝑀𝐶 (6) 𝑅𝑀𝑃: 𝛾𝑑 𝑚𝑎𝑥 = 22.77 − 0.32 𝑂𝑀𝐶 (7) 𝑀𝑃: 𝛾𝑑 𝑚𝑎𝑥 = 23.96 − 0.39 𝑂𝑀𝐶 (8)

Experimental Programme

Materials

For the present experimental study, six field soils

were selected from Mysuru and Chamrajnagar

districts based on liquid limit and clay

mineralogical composition.

Procedure

In order to understand the soil characteristics, the

following physical tests and index property tests

were conducted on the soil samples which were

oven dried, passing through 425µ, as per BIS

specifications: Free swell ratio test [Prakash and

Sridharan [13]], Specific gravity test [IS: 2720

(part-3 sec-1)-1980] [14],Grain size analysis [IS:

2720(part-4)-1985] [15], Atterberg limits [IS: 2720

(part-5)-1985] [16], Cone Penetrometer test using

both water and kerosene as pore fluids [IS: 4968

(part-3)], Compaction tests-Reduced Standard

Proctor test (RSP), Standard Proctor test (SP) [IS:

2720 (part-7)-1980] [17], Reduced Modified

Proctor test (RMP), Modified Proctor test[IS: 2720

(part-8)-1980/1987][18].

About 3kg of soil is thoroughly mixed with the

different water contents and kept inside separate

polythene covers. The samples were let to achieve

the equilibrium moisture for a period of five to ten

days. Later the compaction tests, RSP, SP, RMP

and MP were conducted on these samples to plot

compaction curves. Values of OMC & MDD were

obtained from these Compaction curves for the

soils.

Results and Discussions

Table 1 shows the results of the physical tests done

on the soils. Figure 1 to Figure 6 shows the

compaction curves of the soils with different

energy levels.

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Table 1 Physical properties of the soils

Fig 1 Compaction curve for soil S-1 of Group1



Fig 4 Compaction curve for soil S-4 of Group 2

1.21.31.41.51.61.71.81.9

22.1

0 10 20 30

Dry

de

nsi

ty (

g/cc

)

Water content (%)

RSP

SP

RMP

MP

ZAV LINE (G=2.63)

1.3

1.5

1.7

1.9

2.1

2.3

0 10 20 30

Dry

de

nsi

ty (

g/cc

)

Water content (%)

RSP

SP

RMP

MP

ZAV LINE (G=2.67)

1.4

1.5

1.6

1.7

1.8

1.9

2

0 10 20 30

Dry

de

nsi

ty (

g/cc

)

Water content (%)

RSP

SP

RMP

MP

ZAV LINE (G=2.60)

1.3

1.4

1.5

1.6

1.7

1.8

1.9

0 10 20 30

Dry

de

nsi

ty (

g/cc

)

Water content (%)

RSP

SP

RMP

MP

ZAV LINE (G=2.63)

Soil

G

Grain size distribution (%)

Atterberg limits (%)

IS

classification

clay

silt

sand

WL

WP

PI

WS SI

S-1 K-soil 2.63 50 20 30 35 19 16 7 28 CL

S-2 K-soil 2.67 60 15 25 30 14 16 4 26 CL

S-3 K-soil 2.60 50 22 18 31 17 14 3.1 27.9 CL

S-4 M-soil 2.63 40 20 40 55 20 35 8.4 46.6 CH

S-5 M-soil 2.61 25 40 35 61 28 33 11 50 CH

S-6 K-M-soil 2.72 45 22 33 32 20 12 11.4 20.6 CL




The compaction test results of the soil samples for

different energy levels are shown in Table 2.

Table 2 Compaction test results

Soil

RSP

SP

RMP

MP

OMC

(%)

MDD

(kN/

m3)

OMC

(%)

MDD

(kN/

m3)

OMC

(%)

MDD

(kN/

m3)

OMC

(%)

MDD

(kN/

m3)

S

1

K-

soil 19.1 16.4 17.1 16.7 13.8 18.1 13.4 18.6

S2

K-soil

14.2 18.2 13.5 18.5 10.7 19.32 10.2 19.82

S

3

K-

soil 17 16.15 16 16.42 14.7 16.8 14.4 16.87

S4

M-soil

19 15.7 18.2 16.3 16.6 17.1 16.2 17.4

S

5

M-

soil 28 14 25.2 14.7 20 15.6 19.2 16

S

6

KM

-soil 19.2 16.67 17.7 17.07 16.2 17.85 15 18.54

In order to substantiate the findings from this study

extensive results from published literature have

also been used. Table 3 shows the details of test

results used in this study.

Table 3 Tests results from literature used in this

study. Sl

no.

Compaction energy No.

Of

test

results

Reference

Designation Magnitude

(kj/m3)

1. Reduced

Standard

Proctor*:

RSP

355.5 22

10

6

Blotz et

al.(1998) (19)

Sridharan &

Nagaraj

(2000)***(9)

Y Gurtug & A

Sridharan

(2004)***(10)

2. Standard

Proctor:

SP

592.5 22

10

6

Blotz et

al.(1998) (19)

Sridharan &

H B Nagaraj

(2000)***(09)

Y Gurtug & A

Sridharan

(2004)***(10)

3. Reduced

Modified

Proctor**:

RMP

1616.0 10

6

A Sridharan &

H B Nagaraj

(2000)***(09)

Y Gurtug & A

Sridharan

(2004)***(10)

4. Modified

Proctor:

MP

2693.3 22

10

6

Blotz et

al.(1998)(19)

Sridharan &

Nagaraj

(2000)***(09)

Y Gurtug & A

Sridharan

(2004)***(10) Compaction energy is given here as energy imparted per unit

volume of soil. The compacted volume is 944cc.

* RSP energy is 60% of SP energy

**RMP energy is 60% of MP energy

*** The OMC and MDD are computed as reported by Gurtug and

Sridharan (2004)

Figure 7 & 8 represents the variation of OMC and

MDD obtained from compaction test for various

energy levels with liquid limit of the soils under

study.

1.2

1.3

1.4

1.5

1.6

1.7

0 10 20 30 40

Dry

de

nsi

ty (

g/cc

)

Water content (%)

RSP

SP

RMP

MP

ZAV LINE (G=2.61)

1.4

1.5

1.6

1.7

1.8

1.9

2

0 10 20 30

Dry

de

nsi

ty (

g/cc

)

Water content (%)

RSP

SP

RMP

MP

ZAV LINE (G=2.72)

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Fig 7 Variation of Liquid limit with OMC

Fig 8 Variation of Liquid Limit with MDD

(kN/m3). .

Figures 9 & 10 represent the variation of liquid

limit with OMC and MDD of soils from the

present study and from literature.

Fig 9 Variation of Liquid limit with OMC

Fig 10 Variation of Liquid Limit with MDD.

These figures indicate the absence of any definite

relationship between OMC & MDD of soils with

Liquid Limit, irrespective of clay mineralogical

composition and varying energy levels.

Figure 11 & 12 represents the variation of OMC &


energy levels with Plasticity Index of the soils

under study.

Fig 11 Variation of Plasticity Index with OMC

Fig 12 Variation of Plasticity Index with MDD.

10

15

20

25

30

20 30 40 50 60 70

OM

C (

%)

Liquid Limit Wl(%)

RSP

SP

RMP

MP

10

12

14

16

18

20

22

20 30 40 50 60 70

MD

D

Liquid Limit Wl (%)

RSP

SP

RMP

MP

0

10

20

30

40

50

60

0 50 100

OM

C (

%)

Liquid limit ,Wl (%)

RSP

SP

RMP

MP

0

5

10

15

20

25

0 50 100

MD

D (

kN/m

3)

Liquid limit ,Wl (%)

RSP

SP

RMP

MP

5

10

15

20

25

30

10 20 30 40

OM

C (

%)

Plasticity Index PI (%)

RSP

SP

RMP

MP


Figures 13 & 14 represent the variation of

plasticity index with OMC and MDD of soils from

the present study and from literature.

Fig 13 Variation of Plasticity Index with OMC

Fig 14 Variation of Plasticity Index with MDD

These figures also indicate the absence of any

definite relationship between OMC & MDD of

soils with Plasticity Index, irrespective of clay

mineralogical composition and varying energy

levels.

Figures 15 & 16 represents the variation of OMC

& MDD obtained from compaction test for various

energy levels with Plastic Limit of the soils under

study.

Fig 15 Variation of Plastic Limit with OMC

Fig 16 Variation of Plastic limit with MDD

From these figures, it is observed that, a good

correlation exits between the Plastic Limit and

compaction characteristics which is given by the

regression equation,

OMC = k*Wp (9)

where k= 0.99, 0.91, 0.77, 0.74 for RSP, SP, RMP,

MP with correlation coefficients 0.94, 0.916,

0.905, 0.928 respectively.

Figures 17 & 18 represent the variation of plastic



0

10

20

30

40

50

60

0 20 40 60 80

OM

C (

%)

Plasticity index ,PI (%)

RSP

SP

RMP

MP

0

5

10

15

20

25

0 20 40 60 80

MD

D (

kN/m

3)

Plasticity Index, PI (%)

RSP

SP

RMP

MP

10

15

20

25

30

10 15 20 25 30

OM

C (

%)

Plastic Limit Wp (%)

RSP

SP

RMP

MP

10

15

20

25

10 15 20 25 30

MD

D (

kN/m

3 )

Plastic Limit Wp (%)

RSP

SP

RMP

MP

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Fig 17 Variation of Plastic Limit with OMC

Fig 18 Variation of Plastic limit with MDD

(kN/m3)

From these figures, it can be observed that a good

correlation exist between OMC, MDD with plastic

limit of soils which is given by the regression

equations,

OMC = k1*WP (10)

MDD = k2*WP (11)

where k1 = 0.825, 0.814, 0.989, 0.784 and

k2 = 0.86, 0.84, 0.97, 0.81 for RSP, SP,

RMP and MP respectively.

This explicitly shows that a single parameter

Liquid Limit alone cannot be considered for

correlating compaction characteristics of soils

irrespective of clay mineralogy and energy levels.

Figures 19 & 20 represent the variation of OMC &


energy levels with Shrinkage Limit of the soils

under study.

Fig 19 Variation of Shrinkage Limit with OMC

Fig 20 Variation of Shrinkage Limit with MDD

(kN/m3) From these figures, it can be observed that a good

correlation exist between OMC, MDD with

shrinkage limit of soils under study which is given

by the regression equations,

OMC = k3*WS (12)

MDD = k4*WS (13)

where k3 = 0.721, 0.72, 0.75, 0.69 and

k4 = 0.56, 0.52, 0.42, 0.30 for RSP, SP,


Figures 21 & 22 represent the variation of plastic



0

10

20

30

40

50

60

0 20 40 60

OM

C (

%)

Plastic Limit , Wp (%)

RSP

SP

RMP

MP

0

5

10

15

20

25

0 20 40 60

MD

D (

kN/m

3)

Plastic Limit, Wp (%)

RSP

SP

RMP

MP

0

5

10

15

20

25

30

0 5 10 15

OM

C (

%)

Shrinkage Limit, Ws (%)

RSP

SP

RMP

MP

0

5

10

15

20

25

0 5 10 15

MD

D (

kN/m

3)


RSP

SP

RMP

MP


Fig 21 Variation of Shrinkage Limit with OMC

Fig 22 Variation of Shrinkage Limit with MDD

(kN/m3) From these figures, it can be observed that a good


shrinkage limit of soils under study and from

literature, which is given by the regression

equations,

OMC= k5*WS (14)

MDD= k6*WS (15)

where k5= 0.763, 0.764, 0.764, 0.762 and

k6= 0.76, 0.75, 0.75 and 0.74 for RSP, SP,


Figures 23 & 24 represent the variation of OMC &


energy levels with Shrinkage Index of the soils

under study.

Fig 23 Variation of Shrinkage Index with OMC

Fig 24 Variation of Shrinkage Index with MDD

Table 4 shows equations correlating compaction

characteristics and index properties with regression

coefficients.

Table 4 Equations and regression correlation

coefficients

SL

NO.

VARIABLES

(y Vs x)

PRESENT

STUDY

PRESENT

STUDY &

LITERATURE

1. OMC(RSP)

Vs Wl

y = 0.269x

+ 8.470

R=0.793

y = 0.411x +

4.328

R=0.739

2. OMC(SP) Vs

Wl

y = 0.262x

+ 6.851

R=0.870

y = 0.382x +

3.734

R=0.733

3. OMC(RMP)

Vs Wl

y = 0.181x

+ 7.936

R=0.798

y = 0.285x +

6.819

R=0.592

0

10

20

30

40

50

60

0 20 40 60

OM

C (

%)


RSP

SP

RMP

MP

0

5

10

15

20

25

0 20 40 60

MD

D (

kN/m

3)


RSP

SP

RMP

MP

0

5

10

15

20

25

30

0 20 40 60

OM

C (

%)

Shrinkage Index, SI (%)

RSP

SP

RMP

MP

0

5

10

15

20

25

0 20 40 60

MD

D (

kN/m

3)

Shrinkage Index, SI (%)

RSP

SP

RMP

MP

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4. OMC(MP) Vs

Wl

y = 0.180x

+ 7.384

R=0.826

y = 0.311x +

2.530

R=0.719

5. MDD(RSP)

Vs Wl

y = -0.083x

+ 19.58

R=0.834

y = -0.124x +

21.15

R=0.756

6. MDD(SP) Vs

Wl

y = -0.070x

+ 19.49

R=0.786

y = -0.117x +

21.54

R=0.750

7. MDD(RMP)

Vs Wl

y = -0.068x

+ 20.22

R=0.732

y = -0.086x +

20.07

R=0.600

8. MDD(MP) Vs

Wl

y = -0.070x

+ 20.74

R=0.699

y = -0.112x +

22.77

R=0.734

9. OMC(RSP)

Vs PI

y = 0.276x

+ 13.61

R=0.609

y = 0.237x +

17.96

R=0.266

10. OMC(SP) Vs

PI

y = 0.307x

+ 10.97

R=0.722

y = 0.226x +

16.30

R=0.270

11. OMC(RMP)

Vs PI

y = 0.194x

+ 11.24

R=0.638

y = -0.026x +

22.22

R=0.030

12. OMC(MP) Vs

PI

y = 0.198x

+ 10.55

R=0.678

y = 0.195x +

12.56

R=0.281

13. MDD(RSP)

Vs PI

y = -0.092x

+ 18.13

R=0.692

y = -0.077x +

17.12

R=0.292

14. MDD(SP) Vs

PI

y = -0.076x

+ 18.22

R=0.636

y = -0.076x +

17.81

R=0.303

15. MDD(RMP)

Vs PI

y = -0.074x

+ 19.02

R=0.598

y = 0.004x +

15.50

16. MDD(MP) Vs

PI

y = -0.079x

+ 19.54

R=0.589

y = -0.078x +

19.30

R=0.318

17. OMC(RSP)

Vs Wp

y = 0.987x

R=0.994

y = 0.901x

R=0.825

18. OMC(SP) Vs

Wp

y = 0.914x

R=0.993

y = 0.824x

R=0.814

19. OMC(RMP)

Vs Wp

y = 0.772x

R=0.916

y = 0.709x

R=0.989

Table-5 shows equations correlating compaction

characteristics with shrinkage index of soils under

study with regression coefficients.

Table-5

1 OMC(RSP) Vs SI y = 0.265x + 10.59

R=0.693

2. OMC(SP) Vs SI y = 0.240x + 9.963

R=0.740

3. OMC(RMP) Vs SI y = 0.177x + 9.443

R=0.688

4. OMC(MP) Vs SI y = 0.182x + 8.682

R=0.736

5. MDD(RSP) Vs SI y = -0.089x +

19.14

R=0.785

6. MDD(SP) Vs SI y = -0.075x +

19.12

R=0.742

7. MDD(RMP) Vs SI y = -0.074x +

19.93

R=0.709

8. MDD(MP) Vs SI y = -0.080x +

20.54

R=0.706

From these figures, it can be observed that a good


shrinkage index of soils which is given by the

regression equation,

OMC = k7*SI (16)

MDD = k8*SI (17)

where k7 = 0.69, 0.74, 0.69, 0.74 and

k8 = 0.79, 0.74, 0.71 and 0.71 for RSP, SP,


The results obtained shows that soils with same

liquid limit exhibit different values of OMC and

MDD. This verifies that Liquid Limit and Plasticity

Index alone cannot be correlated to compaction


characteristics satisfactorily. To establish

correlation between compaction characteristics and

shrinkage index more experimental results are

required.

Degree of saturation

The degree of saturation at the optimum

compaction is always less than 100%.Gurtug and

Sridharan (2004)(10) attributed the scatter in the

relationship between the degree of saturation and

OMC to the deviation of the specific gravity of soil

solids used in the computation from its correct

value. It is observed that the degree of saturation

has a tendency to Increase with the increase in the

OMC. An effort is made in this present

experimental work to throw more light on their

observation. S and OMC are related through

equation:

S = G*Wopt / (G*ρw/ρdmax -1) (18)

Where Wopt is OMC and 𝜌dmax is the corresponding

MDD. The values of OMC and MDD are directly

obtained values from the actual tests conducted.

However, the values of S are indirectly calculated

from the above equation, which depends upon the

value of G of the soil. For the given set of (OMC,

𝑀𝐷𝐷) value, the value of S can vary depending

upon the value of G used in the above equation.

Any error committed in obtaining the value of G

from the laboratory tests may lead to an error in the

value of degree of saturation calculated and hence,

contribute to the scatter in the S v/s OMC

relationship. Figures 16 - 19 show the variation of

degree of saturation with water content for soils

under study for different compaction energy levels.

Fig 16 Variation of water content and degree of

saturation (S) for RSP


saturation (S) for SP


saturation (S) for RMP

Fig 19 shows Variation of water content and

degree of saturation (S) for MP

It can be observed that from these figures, the

degree of saturation of soils varies linearly with

water content until OMC irrespective of the clay

mineralogy and compactive effort. Beyond OMC,

0

20

40

60

80

100

0 10 20 30 40

S(%

)

water content (%)

K-S1

K-S2

K-S3

M-S4

M-S5

K-M-S6

0

20

40

60

80

100

120

0 10 20 30 40

S (%

)

water content (%)

K-S1

K-S2

K-S3

M-S4

M-S5

K-M-S6

0

20

40

60

80

100

120

0 10 20 30 40

S (%

)

water content (%)

K-S1

K-S2

K-S3

M-S4

M-S5

K-M-S6

0

20

40

60

80

100

120

0 10 20 30

S (%

)

water content (%)

K-S1

K-S2

K-S3

M-S4

M-S5

K-M-S6

50

th

IG

C




there is a slight non-linear variation in the degree

of saturation.

CONCLUSIONS

Based on the experimental results the following

conclusions can be made:

For various energy levels, the plastic limit can

be better correlated in relative comparison to

liquid limit and plasticity index of the soils

with respect to compaction characteristics i.e

OMC and MDD. Thus, these correlations are

helpful in predicting the compaction

characteristics of soils in field compaction

works.

The compaction characteristics cannot be

explained by only by liquid limit and plasticity

index of the soils.

Degree of saturation of soils varies linearly

with water content until OMC, irrespective of

the clay mineralogy of soils and compactive

effort. Beyond OMC, there is a slight non-

linear variation in the degree of saturation.

Degree of saturation increases sharply until

OMC. Beyond OMC, it increases slightly.

REFERENCES

1. R R Proctor (1933), “Fundamental principles of

soil compaction”, Engineering News Record,

Vol.111, No.9-10, pp.12-13.

2. C A Hogentler (1936), “Essentials of soil

compaction”, Proceedings of Highway

Research Board, NRC, Washington DC,

pp.309-316.

3. J W Hilf (1956), “A rapid method of

construction control for embankments of

cohesive soils”, Engrg. Monograph, US Bureau

of Reclamation Denver, Colorado, (26), pp.1-

29.

4. R E Oslon (1963), “Effective stress theory of

soil compaction”, Journal of Soil Mechanics

and Foundation Engineeering Division, ASCE,

Vol.89, pp.27-45.

5. L Barden and G R Sides (1970), “Engineering

behaviour and structure of compacted clay “,

Journal of Soil Mechanics and Foundation

Engg. Division, ASCE, Vol.94, No.4, pp.87-

101.

6. T S Nagaraj and B R Srinivasmurthy (1983),

“Rationalization of Skempton’s compressibility

equation”, Geotechquie, Vol.36, No.1, pp.27-

32.

7. A. Gens (1996), Constitutive modelling:

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Unsaturated Soils, September 1995, Paris. A.

A. Balkema, Rotterdam. Vol. 3, pp. 1179-1200.

8. N S Pandian, T S Nagaraj and M Manoj

(1997), “Re-examination of compaction

characteristics of fine-grained soils”,

Geotechnique, Vol.47, No. 2, pp 363-366.

9. A Sridharan and H B Nagaraj (2000).

“Compressibility behaviour of remoulded fine-

grained soils and correlation with index

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10. Y Gurtug and A Sridharan,(2004),”Compaction

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to compaction energy”, Soils and Foundation,

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11. A Sridharan and H B Nagaraj (2005), “Plastic

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grained soils, Ground Improvement, 9, No.1,

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12. V Sivakumar, SJ Wheeler (2000) Influence of

compaction procedure on the mechanical

behaviour of an unsaturated compacted clay.

Part 1: Wetting and isotropic compression,

Géotechnique 50 (4), pp. 359-368.

13. K. Prakash, and A. Sridharan, (2004), ‘Free

swell ratio and clay mineralogy of fine grained

soils’, Geotechnical Testing Journal, ASTM,

Vol. 27, No.2, pp.220-225.

14. IS: 2720-Part 3/Sec-1 (1980), Indian standard

methods of test for soils: Determination of

Specific gravity. Bureau of Indian Standards,

New Delhi.

15. IS: 2720-Part 4 (1985), Indian standard

methods of test for soils: Grain size analysis,

Bureau of Indian Standards. New Delhi.




liquid limit and plastic limit (second revision),

Bureau of Indian Standards, New Delhi.



water content-density relation using light

compaction (Second revision), Bureau of

Indian Standards, New Delhi.



water content- Dry density relation using heavy

compaction (Second revision), Bureau of

Indian Standards, New Delhi.

19. Blotz, L. R., Benson, C. H and Boutwell, G.P.

(1998) ‘Estimating optimum water content and

dry unit weight for compacted clays’, Journal

of Geotechnical and Geo-environmental

Engineering, Vol-124, No.9, pp. 907-912.

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