Swell Characteristics of Natural and Treated Compacted Clay

7/27/2019 Swell Characteristics of Natural and Treated Compacted Clay

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Swell Characteristics of Natural and

Treated Compacted Clays

Mohammed Shukri Al-Zoubi

Civil Engineering Department

Faculty of Engineering / Mutah University

[email protected]

ABSTRACTThis study investigates the swell characteristics of a highly plastic clay in its natural stateand after this clay was separately treated with potassium and calcium chlorides. Freeswell tests were conducted on these three (natural and treated) soils at two differenttemperatures (26C and 40C) This study shows that a linear relationship exists between

the percent free swell and the liquid limit for the tested soils at given water content, drydensity, and temperature and also shows that these soils are not susceptible to expansion

when the liquid limit drops below about 40 % regardless of the initial states of watercontent and dry density as well as test temperature. This study confirms that the percentfree swell may reliably be modelled by a rectangular hyperbolic equation as a function oftime and liquid limit. The influence of temperature on the swell potential are observed tobe dependent on initial compaction states.

KEYWORDS: swell potential, expansive soils, rectangular hyperbola,compaction, liquid limit, and plasticity index.

INTRODUCTION

Expansive soils are a worldwide problem. The hazards posed by expansive soils with regard

to the civil engineering structures (buildings, roads, pavements, slab-on-grade, and other

lightly loaded structures) have been documented the world over (Likos, 2004) The estimateddamage caused to these structures by expansive soils amounts to billions of US dollars

annually (Jones 1973; Sheriff et al. 1982)

The solutions to problems of foundations on expansive soils require understanding the

fundamental characteristics of expansive soils and the involved variables that affect the

swelling phenomenon. The swelling behavior of soils is influenced by many physical and

environmental factors that contribute to the expansive nature of a soil; these factors include

the type and amount of clay minerals, physicochemical properties of pore fluid, soil density,

water content, plasticity indices, surcharge pressure, temperature, and time (Nayak and

Christensen 1971; Sherif et al. 1982, Hilf 1991) Aging also affects the swelling potential of

soils (Rao and Tripathy 2003)

Numerous theoretical and experimental studies have shown that correlations for identifying

and predicting the swell potential utilizing the basic properties of soils do exist (e.g., Holtz
mailto:[email protected]:[email protected]


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and Gibbs 1956; Holtz 1959; Ladd 1960; Seed et al. 1962; Van Der Merwe 1964;

Ranganatham and Satyanarayan 1965; Komornik and David 1969; Vijayvergiya and Gazzaly

1973; Nayak and Christensen 1971; O'Neill and Gazzaly 1977; Johnson and Snethen 1978;

Sherif et al. 1982; Snethen 1984; Chen 1988; Mckeen 1992; Yilmaz 2006) Different forms of

relationships between the swell potential or swell pressure and the basic soil properties were

suggested. For example, Seed et al (1962) empirically correlated the swell potential with the

soil activity and plasticity index whereas O'Neil and Ghazzaly (1977) developed an empirical

equation for the swell potential utilizing liquid limit and water content. On the other hand,

Nayak and Christensen (1971) devised a semi-empirical equation for both the swell potential

and swell pressure based on plasticity index, clay fraction, and water content. The presence of

these different forms may be attributed to the limitations involved in applying either the

theoretical studies that involve several simplifying assumptions and/or the empirical

investigations that are valid only statistically particularly for the specific soils for which the

empirical correlations were developed (e.g., Nayak and Cristensen 1971)

This study utilizes results of free swell tests on a highly expansive clay in its natural(untreated) state and after treatment with potassium chloride (KCl) and calcium chloride

(CaCl2) in order to contribute to the understanding of the fundamental swell characteristics.

This highly expansive clay (in its untreated and treated conditions) was tested at two different

temperatures and three different states of water content and dry density in order to investigate

the effect of these factors (water content, dry density, temperature, pore fluid) on the swelling

characteristics of this clay. Based on the results of present study, a general model is proposed

based on a linear relationship between swell potential and liquid limit for predicting the

amount and the time history of swell a soil of a given mineralogy and consistency might

exhibit. This general model is validated by experimental and theoretical studies obtained from

literature.

EXPERIMENTAL PROGRAM

Soils and Testing Procedures

In this study, results of free swell tests conducted in the oedometer apparatus on the highly

plastic Azraq Green Clay (AGC) in its natural state and after treatment with the two salts

(KCl and CaCl2) are utilized in order to assess the swell characteristics and the factors

affecting swell behavior of soils. The selection of this clay was motivated by utilizing a

natural soil with known mineralogical composition in order to minimize the number of

variables affecting the soil swell characteristics. However, different factors such as water

content, dry density, test temperature, and pore fluid are investigated. The Azraq Green Clay

was obtained from the Azraq basins, Jordan. This clay includes clay minerals such as mixedlayer illite/smectite, kaolinite, palygorskite, montmorillonite, discrete illite (Abdullah et al.

1999)

Treatment of the clay with salts was to make a specific species of cations dominant in the

exchange complex. The clay was treated with concentrated solution (1 normality

concentration) of the selected salt (potassium or calcium chloride) In each case, the clay was

washed three times with the solution and became nearly homo-ionic; the alteration procedure

and results are described in more detail by AL-Zoubi (1993) and Abdullah et al. (1999) The

liquid and plastic limits of the untreated and treated clays were measured in line with the

procedure of ASTM-D4318 (Standards of the American Society of Testing and Materials)

The basic properties of this soil in its untreated and treated states are summarized in Table 1.As can be seen from this table, the liquid limit decreased after treatment with the two salts.

Figure 1, which represents the plasticity chart, shows that untreated and Ca treated soils can


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be classified as CH (clay with high plasticity) and K treated soil may be classified as MH

(silt with high compressibility) according to the Unified Soil Classification System.

Table 1: The basic properties of the untreated and treated Azraq Green Clay

utilized in the present study.

Soil

Particle size Compaction Liquidlimit

(%)

PlasticLimit

(%)

Sand

(%)

Silt

(%)

Clay

(%)

Opt.Water

Content(%)

Max.dry

density(kN/m

3)

Untreated 8 23 69 31.5 12.8 107.8 42.0

Ca - treated ----- ---- ----- 23.0 14.3 72.0 30.9K - treated 8 52 40 23.5 14.1 54.5 42.7

Figure 1: Plasticity chart showing the change in liquid limit and plasticity index before and

after treatment of the Azraq Green Clay.

For the free swell tests, all the specimens were compacted directly inside the oedometer ring

by using a special mold to a pre-specified dry density at given molding water content. The

ring was 76 mm in diameter and 20 mm in height. These specimens were compacted at threedifferent initial states of water content and dry density as demonstrated in Fig. 2, which shows

the results of the standard Proctor compaction test (ASTM-D698-78) on the untreated soil.

The three states were selected to be on the dry side of optimum and at optimum water content

where the swell potential is considerably higher than those on the wet side of optimum.

Liquid Limit , LL , %

0 20 40 60 80 100 120

P

lasticityIndex,PI,%

0

20

40

60

80

Natural clay

Ca - treated clay

K - treated clay

A-lin

e


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Figure 2: Standard Proctor compaction curve and selected states of water content and dry

density for the present study.

Figure 3: Free swell-time curves for untreated Azraq Green Clay (a) ato

26 C (b) ato

40 C.

water content , %

20 30 40 50

drydensity,g/cc

1.15

1.20

1.25

1.30

1.35

1.40

1.45

wopt = 31.5 %

dmax

= 1.30

satura

tionlin

e

states investigateddry of optimumoptimum - 1optimum - 2

Azraq Green Clay

time , min

0 50 100 150 200

deformation,

H,0

.002mm

0

1000

2000

3000

AGC - 1

AGC - 2

AGC - 4

Natural clay

at 26o

C

sl-time3.spw

time , min

0 50 100 150 200

deformation,

H,0.002mm

0

1000

2000

3000

Natural clayat 40

oC

AGC - 21

AGC - 22

AGC - 24


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Figure 4: Free swell-time curves for Ca-treated Azraq Green Clay

(a) at 26C (b) at 40C.

time , min

0 50 100 150 200 250

deformation,0.002m

m

0

500

1000

1500

2000

AGC - 6

AGC - 7

AGC - 9

Ca - treated clay

at 26o

C

time , min

0 50 100 150 200 250

d

eformation,0.002mm

0

500

1000

1500

2000

AGC - 26

AGC - 27

AGC - 29

Ca - treated clay

at 40o

C


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Figure 5: Free swell-time curves for K-treated Azraq Green Clay

(a) at 26C (b) at 40C.

time , min

0 50 100 150

deformation,0.002mm

0

500

1000

AGC - 11

AGC - 12

AGC - 14

K - treated clay

at 26

o

C

time , min

0 50 100 150

deformation,0.002mm

0

500

1000

K - treated clay

at 40o

CAGC - 31

AGC - 32

AGC - 34

time , min

0.1 1 10 100 1000

Percentfreeswell,

FS,%

0

5

10

15

20

25

30

AGC - 21 at T = 40o

C

r= 21.55 %

tr= 90 min

tr : reference time

r : reference strain


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Figure 6: Typical percent free swell-time curve.

The influence of pore fluid chemistry on the swelling behavior of this soil is described by

Alshibli (1992) and Abdullah et al. (1999) and on the consolidation behavior can be found in

AL-Zoubi (1993) and Abdullah et al. (1997)

In the free swell test, the specimen was placed in the oedometer apparatus under a surcharge

of about 6.9 kPa (1 psi) Distilled de-ionized water was then added to the sample, and the

increase in the height of the specimen (volume expansion under constant cross sectional area)

was recorded for one day (all specimens reached equilibrium within this period) The percent

free swell may be expressed as

100

0

xH

H

FS

(1)

H is height of swell due to saturation and 0H is the original height of specimen.

The temperature at which the tests were conducted was controlled by modifying the

oedometer apparatus as described in detail by Abdullah et al. (1997) The temperature was

measured at four different locations inside trial specimens that were tested ato

40 C and was

found to range withino

5.1 C during the entire test.

Analysis and interpretation of the experimental results

The free swell curves, shown in Figs. 3 to 5, were obtained by plotting the free swell, H , as

a function of time, t. Figures 3(a), 4(a), and 5(a) show the results of tests conducted ato

26 Cfor the untreated, Ca treated, and K treated soils, respectively, on the other hand, Figs.

3(b), 4(b), and 5(b) show the results of tests conducted ato

40 C for the untreated, Ca

treated, and Ktreated soils, respectively.

It can be seen from Figs. 3 trough 5 that the curves, which correspond to two different

temperature, three different states of water content and dry density, and three different pore

fluids, are similar in shape even though these curves exhibit different amount and rate of

swell. This similarity suggests that these curves can be normalized and then mathematically

expressed by an equation. This can be achieved by dividing the ordinates and abscissas,

respectively, by a reference swell and reference time. The reference parameters can be

identified arbitrarily in different ways. One way of identifying these reference parameters is to

use graphical construction to obtain "end of primary swell" similar to that of the log t method

(Casagrande and Fadum 1940) utilized for identifying end of primary consolidation since soil

swelling is similar but opposite to soil consolidation. Figure 6 shows the free swell against

logarithm of time and the procedure to obtain the end of primary swell where the ordinate is

identified as the reference percent free swell, rFS

, and the abscissa as the reference time,

rt .

All the results of free swell tests of Figs. 3 to 5 were normalized by dividing the ordinates by

the reference percent free swell, rFS

, and the abscissa by reference time,rt . The

normalized results are plotted in Fig. 7. As can be seen from Fig. 7, the results may be

represented mathematically by a hyperbolic function of the following form


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20.0/80.0/

r

r

rFS

FS

tt

tt

(2)

A rectangular hyperbolic function was also suggested by different researchers (e.g., Sherif etal. 1982; Komine and Ogata 1992; Abdullah et al. 1997) as a mathematical model for

presenting the swell - time relationship.

The maximum possible free percent swell value may be obtained by taking the limit of Eq. 2

as time approaches infinity and thus may be expressed in terms of the reference swell as

follows

rFSFS

25.1max

(3)

Combining Eqs. 2 and 3, the following expression is obtained for percent free swell and time

relationship

25.0//

max

r

r

FS

FS

tt

tt

(4)

Sherif et al. (1982) called the right hand side of Eq. 4 as the swell invariant function.

Based on Eq. 4, the percent free swellFS

at any time t may be obtained if the maximum

percent swell value maxFS

and the reference timert are known. Therefore, a procedure to

assess maxFS

must be developed in order to utilize Eq. 4 for predicting the amount and rate

of swell.

Figure 7: Normalized percent free swell - time curve

for all the soil specimens of the present study.

Normalized time , t / tr

0 1 2 3 4

Normalized

percentfreeswell,

/r

0.0

0.4

0.8

1.2

1.6

20.0/80.0

/

r

r

rtt

tt

Results of 18 specimens of untreated and treated AzraqGreen Clay; same data of Figs. 3 to 5 including the variationsof temperature, water content, and dry density.


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Figure 8: Maximum percent free swellliquid limit relationship for T= 26C.

In order to achieve this objective, the maximum percent free swell values maxFS

were

calculated for the soil samples shown in Figs. 3 to 5 as a function of test temperature, water

content, and dry density using the procedure shown in Fig. 6 and Eq. 3. These maxFS

values are plotted against the liquid limit ( LL ) in Figs. 8 and 9. As can be seen from these

figures, a linear relationship does exist between

maxFS and liquid limit ( LL ) for given test

temperature, water content, and dry density. This relationship can be expressed as follows

0max

LLLLBFS

(5)

where B is the slope of the LLFS

max

linear relationship and0

LL is the liquid limit

below which soils are not susceptible to expansion. Figures 8 and 9 show that the0

LL value

for the tested clays is equal to about 40 % regardless of the initial states of water content and

dry density and test temperature.

Combining Eqs. 4 and 5, a general model for predicting the percent free swell may be

expressed as follows

25.0/

/

0

r

r

FS

tt

ttLLLLB (6)

where the B value for a given soil is generally a function of water content, dry density, and

test temperature as can be seen from Figs. 8 and 9.

Liquid limit , LL , %

0 20 40 60 80 100 120

maximum

percentfreeswell,MPF

S,%

0

10

20

30

40

Untreated and treatedAzraq Green ClayTemperature = 26

oC

optimum 2

optimum 1

dry of optimum MPFS = 0.336 (LL - 40)

MPFS = 0.276 (LL - 40)

MPFS = 0.168 (LL - 40)


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Figure 9: Maximum percent free swellliquid limit relationship for T= 40C.

The influences of water content and test temperature on the B value are shown in Fig. 10.

Despite the limited number of data points, Fig. 10 (a) shows that the B value generally

decreases with the increase of initial water content for a given test temperature whereas Fig.

10(b) shows that the B value increases with the increase of test temperature and the rate of

increase depends on the initial compaction state.

Figure 10: Effect of initial water content and temperature on the B value.

A linear relationship between percent free swell and liquid limit can also be established from

the experimental results obtained from the literature (e.g., Nayak and Christensen 1971;

O'Neil and Gazzaly 1977; okca 2002; and Yilmaz 2006) The experimental results of free

swell tests conducted on specimens compacted at optimum (standard ASSHTO compaction

test) from laboratory prepared grundite-bentonite and kaolinite-bentonite mixtures reported by

Nayak and Christensen (1971), shown in Fig. 11, support the linearity of the percent freeswell-liquid limit relationship. This relationship can be given as follows

Liquid limit , %

0 20 40 60 80 100 120

maximum

percentfreeswell,MPFS,%

0

10

20

30

40

Untreated and treatedAzraq Green ClayTemperature = 40

oC

optimum 2optimum 1

dry of optimum MPFS = 0.524 (LL - 40)

MPFS = 0.317 (LL - 40)

MPFS = 0.187 (LL - 40)

molding water content

20 25 30 35

ValueofB

0.1

0.2

0.3

0.4

0.5

0.6

0.7

dry density = 1.25 g/cm3

40o

C

26o

C

wopt

= 31.5 %

temperature ,o

C

20 25 30 35 40 45

dry of optimum

Optimum - 1

Optimum - 2

(a) (b)


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6.21427.0 LLFS

(7)

The coefficient of determination2

r and the standard error of estimate SEE are 0.971 and

1.79 %, respectively.

Figure 11: Percent free swell vs. liquid limit (data from Nayak and Christensen 1971)

Figure 12: Percent free swell data on compacted kaolinite - bentonite mixtures

(data from okca, 2002)

The experimental results reported by okca (2002) also exhibit a linear relationship between

the percent free swell and liquid limit as shown in Fig. 12 that can be expressed in a similarway to the proposed model as follows


0 30 60 90 120 150

PercentFreeSwell,PFS,%

0

20

40

60

PFS = 0.427 (LL - 21.6)

Data from Nayak and Christensen (1971)on compacted soil samples with watercontent and dry density at optimum.


0 100 200 300

Percen

tFreeSwell,PFS,%

0

100

200

PFS = 0.672 (LL - 7.3)

Data from Cokca (2002) on mixturesof kaolinite and bentonite.

r = 0.9967


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3.7672.0 LLFS

(8)

The coefficient of determination2

r for this equation is 0.997.

Figure 13: Percent free swell of undisturbed soil samples with variety of water content and

dry density (data from US Bureau of Reclamation reported by Seed et al. 1962)

It should, however, be pointed out that the relationship between the percent free swell and

liquid limit may exhibit considerable scatter when the variations of the water content, dry

density, and/or temperature are not taken into consideration in obtaining this relationship as

can be seen from Fig. 13, which shows the experimental results of the US Bureau of

Reclamation on percent free swell reported by Seed et al. (1962) for undisturbed soil samples

with variety of water content and dry density. In order to demonstrate that the considerable

scatter observed in these results of the US Bureau of Reclamation may be attributed to the

variations of the initial water content, dry density, and/or temperature, Fig. 14 was prepared

such that the maximum percent free swell of the soils utilized in the present study (presented

earlier in Figs. 8 and 9) is plotted against the liquid limit regardless of the initial compaction

states and test temperature. As can be seen, the results of Fig. 14 exhibit similar considerable

scatter as that of Fig. 13 when the compaction conditions and test temperature are ignored in

developing a model for predicting the swell potential. Despite the scatter, Fig. 13 generally

supports the findings of the present study that a linear relationship exists between the percentfree swell and liquid limit particularly as can be seen from the lower and upper limits

represented by the dashed lines in Figs. 13 and 14.


0 20 40 60 80 100

Perc

entFreeSwell,PFS,%

0

20

40

60

PFS=0.72

3(LL

-12)

PFS=0.37

3(LL-

25)

Data of the US Bureau of Reclamationobtained from Seed et al. (1962) onundisturbed soil samples with varietyof water content and dry density

due to variation of water content,dry density, and/or temperature


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Figure 14: results of percent free swell of the present study regardless of compaction

conditions and test temperature.

Experimental Validity of the proposed model for

predicting swell potential

The experimental results of the soils of the present study as well as those of the Nayak and

Christensen (1971) are utilized in order to assess the proposed model as shown in Figs. 15 and16. Figure 15 compares the one-day percent free swell predicted using Eq. 6 and the actual

one-day percent free swell observed from swell tests conducted on 18 specimens at two

different temperatures and three different initial states of water content and dry density. Fig.

16 compares the percent free swell values predicted by the proposed model and actual values

obtained from Nayak and Christensen (1971) As can be seen from Figs. 15 and 16, the

proposed model can reliably be utilized for predicting the swell potential of these soils.

Liquid limit , LL , %

0 20 40 60 80 100 120

maximum

percentfreeswell,MP

FS,%

0

10

20

30

40

0 20 40 60 80 100 1200

10

20

30

40

PFS

=0.524

(LL

-40)

PFS=0

.168(LL

-40)

Results of the present study regardless

of water content, dry density, and test

temperature.

due to variation of water content,dry density, and/or temperature

actual free swell at 24 hr , %

0 10 20 30 40

predictedfreeswellat24hr,%

0

10

20

30

40

Results of three soilsof the present study

at two temperatures


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Figure 15: Comparison of predicted and actual one-day percent free swell values.

Figure 16: Comparison of predicted and actual percent free swell values

(data from Nayak and Christensen 1971)

Theoretical Validity of the proposed model for predictingswell potential

Every empirical rule is valid only statistically. Therefore, the proposed empirical model must

be supported by theoretical basis to be reliably and usefully utilized for predicting the swell

behavior of all soils. Nayak and Christensen (1971) derived a basic form of the theoretical

relationship between percent free swell and basic properties of soils from the consideration of

the diffuse double layer and the osmotic pressure for parallel clay plates. Nayak and

Christensen (1971) showed that this relationship might be given by the following expression

m

m

mFSK

w

CEK "' (9)

wherem

K' ,m

K" , and m are empirical constants; E can, according to Nayak and

Christensen (1971), be taken as the liquid limit, plasticity index, or shrinkage index.

Nayak and Christensen (1971) found statistically that the percent free swell as a function of

the plasticity index, water content, and clay content can be expressed as follows ( E was

taken as the plasticity index)

38.61029.2 45.12 w

CPIx

FS (10)

As can be seen from Eq. 10, the percent free swell is a nonlinear function of the plasticity

index and depends on the ratio of the clay content to water content.

Actual percent free swell , %

0 20 40 60

Predictedpercentfreeswell,%

0

20

40

60

Data from Nayak and Christensen (1971) oncompacted soil samples with variety of watercontent and dry density at optimum.


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However, in the present study, the experimental results of Nayak and Christensen (1971) are

re-plotted in terms of the percent free swell as a function of liquid limit as depicted in Fig. 11.

Figure 11 shows that a linear relationship exists between the percent free swell and liquid

limit for the experimental results of Nayak and Christensen (1971) for which the exponent m

is equal to unity. Therefore, Eq. 10 can be rewritten in a similar form to the proposed model

as follows ( E is taken as the liquid limit, LL)

0

' LLLLBFS

(11)

where

w

CKB

m'

' (12)

CK

wKLL

m

m

'

"

0 (13)

Figure 11 shows that 'B and0

LL values are practically constants and equal to 0.427 and 21.6

%, respectively.

Furthermore, empirical and statistical correlations on free swell test results such as O'Neil and

Gazzaly (1977) also support the findings of the present study in the sense that a linear

relationship does exist between the percent free swell and liquid limit at given water content,

dry density, and test temperature. O'Neil and Gazzaly (1977) suggested the following

empirical model for predicting the amount of swell of a soil based on statistical analysis

cFSwLL 27.0131.027.2 (14)

Equation 14 can be rewritten in the following form

0

131.0 LLLLFS

(15)

where 131.027.227.00

c

wLL ; at a given water content of 28.4 % which is the

average water content use in the present study, the value of 410LL % which is very close

to the observed value in the present study.

It should be mentioned that the experimental results of the present study (Figs. 8 and 9) as

well as those of Nayak and Christensen (Fig. 11) suggest that the value of0

LL is independent

of the placement conditions; however, this value may be dependent on the mineralogy of the

tested soils. The experimental results obtained from literature as well as those of the present

study show that the0

LL value may range from about 7 to 40 %. On the other hand, the

empirical model of O'Neil and Gazzaly (1977) suggests that the0

LL value is a function of

water content.

It should also be mentioned that the existing correlations, such as those described above, do

not take into consideration the effect of test temperature that may be significant in many cases

as demonstrated in Fig. 17, which compares the maximum percent free swell valuescalculated for the nine specimens tested at

o40 C to those of the corresponding nine


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specimens tested ato

26 C. As can be seen from Fig. 17, the maximum percent free swell

values obtained ato

40 C are generally larger than those obtained ato

26 C and the largest

difference is observed for the specimens compacted at the dry side of optimum. Figure 17

suggests that the effect of temperature on the swell potential depends on the initialcompaction state of water content and dry density. Therefore, for any general correlation to be

reasonably successful for predicting the swell characteristics of all soils must account for the

test temperature.

Figure 17: Effect of temperature on maximum percent free swell.

CONCLUSIONS AND RECOMMENDATIONS

This study presents an experimental investigation on swell characteristics of a highly plastic

natural clay that was also treated with potassium chloride and calcium chloride. Free swell

tests were conducted on these three untreated and treated soils at two different temperatures (o

26 C ando

40 C) This study confirms that the percent free swell for the tested soils may

reliably be modeled by a rectangular hyperbolic equation as a function of time and liquidlimit. This study shows that a linear relationship exists between the maximum possible

percent free swell and the liquid limit at given water content, dry density, and test

temperature.

A general model is proposed for estimating the amount of swell for all types of soils utilizing

the observed linear relationship between percent free swell and liquid limit. This model is

shown to be supported by experimental results, empirical correlations, and theoretical studies

obtained from literature.

The present study shows that the slope of the observed percent free swell liquid limit linear

relationship varies as a function of test temperature, water content, and dry density; further

investigations may be required to clarify these variations and model them mathematically.This is recommended to be achieved by testing a wider range of natural or compacted soils

Maximum percent swell at 26o

C, %

0 10 20 30

Maximum

percentswellat40oC,%

0

10

20

30

dry of optimum

optimum - 1

optimum - 2


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under different initial states of water content and dry density under a wider range of test

temperatures.

REFERENCES

1. Abdullah, W.S., Al-Zoubi, M.S., and Alshibli, K.A. (1997) On the physicochemicalaspects of compacted clay compressibility. Canadian Geotechnical Journal 34: 551-

559.

2. Abdullah, W.S., Alshibli, K.A, and Al-Zoubi, M.S. (1999) Influence of pore waterchemistry on the swelling behavior of compacted clays. Applied Clay Science, vol.

15, pp. 447 - 462.

3. Alshibli, K.A. (1992) Effect of physicochemical changes on swelling characteristicsof Azraq Green Clay. Thesis submitted in partial fulfillment of the requirements forthe Degree of Master of Science in Civil Engineering at Jordan University of Science

and Technology. 138 p.

4. AL-Zoubi, M.S. (1993) Effect of physicochemical changes on the compressibility ofa selected Azraq Green Clay. Thesis submitted in partial fulfillment of the

requirements for the Degree of Master of Science in Civil Engineering at Jordan

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Swell Characteristics of Natural and Treated Compacted Clay