Proceedings of Indian Geotechnical Conference December 15-17,2011, Kochi (Paper No. H-304)

SOIL STABILIISATION USING RAW PLASTIC BOTTLES

Anas Ashraf, B. Tech final year student, College of Engineering Trivandrum, anas_577@yahoo.co.in Arya Sunil, B. Tech final year student, College of Engineering Trivandrum, aryasunil89@gmail.com J. Dhanya, B. Tech final year student, College of Engineering Trivandrum, dhanyaj17@gmail.com Mariamma Joseph, Professor, College of Engineering, Trivandrum, mjh_mariamma@yahoo.co.in Meera Varghese, B. Tech final year student, College of Engineering Trivandrum, meera_varghese@yahoo.com

M. Veena, B. Tech final year student, College of Engineering Trivandrum, veenam_20jul@yahoo.co.in

ABSTRACT: Soil stabilisation is any process which improves the physical properties of soil, such as increasing shear

strength, bearing capacity etc. which can be done by use of controlled compaction or addition of suitable admixtures like

cement, lime and waste materials like fly ash, phosphogypsum etc. The cost of introducing these additives has also

increased in recent years which opened the door widely for the development of other kinds of soil additives such as

plastics, bamboo etc. This new technique of soil stabilisation can be effectively used to meet the challenges of society, to

reduce the quantities of waste, producing useful material from non-useful waste materials. Use of plastic products such as

polythene bags, bottles etc. is increasing day by day leading to various environmental concerns. Therefore the disposal of

the plastic wastes without causing any ecological hazards has become a real challenge. Thus using plastic bottles as a soil

stabiliser is an economical utilization since there is scarcity of good quality soil for embankments. This project involves the

detailed study on the possible use of waste plastic bottles for soil stabilisation. The analysis was done by conducting plate

load tests on soil reinforced with layers of plastic bottles filled with sand and bottles cut to halves placed at middle and one-

third positions of tank. The comparison of test results showed that cut bottles placed at middle position were the most

efficient in increasing strength of soil. The optimum percentage of plastic strips in soil was found out by California Bearing

Ratio Test and using this percentage of plastic, plate load test was also performed. The size and content of strips of waste

plastic bottles have significant effect on the enhancement of strength of the soil.

INTRODUCTION

Soil stabilisation means the improvement of stability or

bearing power of the soil by the use of controlled

compaction, proportioning and/or the addition of suitable

admixture or stabilisers. The basic principles of soil

stabilisation are:

Evaluating the properties of given soil.

Deciding the lacking property of soil and choose

effective and economical method of soil stabilisation.

Designing the stabilised soil mix for intended stability

and durability values.

Stabilisation can increase the shear strength of a soil and/or

control the shrink-swell properties of a soil, thus improving

the load bearing capacity of a sub-grade to support

pavements and foundations. Stabilisation can be used to

treat a wide range of sub-grade materials from expansive

clays to granular materials. The most common

improvements achieved through stabilisation include better

soil gradation, reduction of plasticity index or swelling

potential, and increases in durability and strength. In wet

weather, stabilisation may also be used to provide a

working platform for construction operations. These types

of soil quality improvement are referred to as soil

modification. Benefits of soil stabilisation are higher

resistance values, reduction in plasticity, lower

permeability, reduction of pavement thickness, elimination

of excavation, material hauling and handling, and base

importation, aids compaction, provides all-weather access

onto and within projects sites. The determining factors

associated with soil stabilisation may be the existing

moisture content, the end use of the soil structure and

ultimately the cost benefit provided.

As good soil becomes scarcer and their location becomes

more difficult and costly, the need to improve quality of

soil using soil stabilisation is becoming more important.

Soil stabilisation using raw plastic bottles is an alternative

method for the improvement of subgrade soil of pavement.

It can significantly enhance the properties of the soil used

in the construction of road infrastructure.

RESEARCH SIGNIFICANCE

For many years, road engineers have used additives such as

lime, cement and cement kiln dust to improve the qualities

of readily available local soils. Laboratory and field

performance tests have confirmed that the addition of such

additives can increase the strength and stability of such

soils. However, the cost of introducing these additives has

also increased in recent years. This has opened the door

widely for the development and introduction of other kinds

of soil additives such as plastics, bamboo, liquid enzyme

soil stabilizers etc.

Soil stabilisation using raw plastic bottles is an alternative

method for the improvement of subgrade soil of pavement.

It can significantly enhance the properties of the soil used

in the construction of road infrastructure. Results include a

489

Anas Ashraf, Arya Sunil, J. Dhanya, Mariamma Joseph, Meera Varghese & M. Veena

better and longer lasting road with increased loading

capacity and reduced soil permeability. This new technique

of soil stabilisation can be effectively used to meet the

challenges of society, to reduce the quantities of waste,

producing useful material from non-useful waste materials

that lead to the foundation of sustainable society. It can be

effectively used in strengthening the soil for road

embankments and in preparing a suitable base for the upper

pavement structure. Since it increases the bearing capacity

of soil considerably, the land use can be increased. It can

lower the road construction and maintenance costs while

increasing the overall quality of its structure and surface.

The promise that soil stabilisation technology can actually

improve the mechanical qualities of local road soil so that

stronger, more durable roads can be built has prompted

national road ministries around the world to conduct

extensive testing to verify that this new technology is truly

cost-effective. The result is that this new advance in soil

stabilisation technology is increasingly being used in both

constructing and improving/rehabilitating unsurfaced and

paved roads worldwide.

MATERIALS AND METHODOLOGY

In order to conduct this study, various materials such as

lateritic soil, plastic bottles (both cut and uncut), sea sand

and synthetic threads were used.

The Standard Proctor Compaction tests were done to assess

the amount of compaction and the water content required in

the field [1]. The water content at which the maximum dry

density is attained is obtained from the relationships

provided by the tests.

The California Bearing Ratio test was conducted to

determine the optimum amount of plastic strips in soil. This

is done by mixing soil with varying percentages (0.0%,

0.2%, 0.4% etc.) of plastic strips in soil and the 4 day

soaked CBR Value is obtained. [2].Plate load tests were

conducted with plain lateritic soil, soil stabilised with full

bottles, soil stabilised with bottles cut to two halves and

soil stabilised with optimum percentage of plastic strips[3].

Load-settlement graphs for each plate load test were drawn.

For each load-settlement graph, the load corresponding to

4mm settlement was noted. The ultimate load and

corresponding settlement of the plate is also determined

from the load- settlement graph plotted for various test

arrangements.

RESULTS AND DISCUSSIONS

COMPACTION TEST

From the compaction curve, the maximum dry density and

optimum moisture content were obtained as 18.95kN/m3

and 11.22 % respectively. This is used for finding the bulk

density of the soil filled in the tank for plate load test. The

California Bearing Ratio test was also carried out by

mixing the soil with optimum moisture content

Fig. 1 Compaction curve

CBR TEST

Table 1 CBR Values for soil with varying percentages of

plastic strips

% of Plastic Content CBR Value

0.0 1.9

0.2 1.7

0.4 1.8

0.6 2.5

0.8 1.3

1.0 1.3

0

1

2

3

0 0.5 1 1.5

CB

R v

alu

e

Percentage of plastic content

Fig. 2 Relation between CBR Value and percentage of

plastic content

It is observed from the test results that for soil mixed with

waste plastic strips, soaked CBR values increased from

1.967 to 2.479 with 0.6% of plastic and there after

decreased. Hence the optimum percentage of plastic strip in

soil is found to be 0.6%. It was also observed that there was

a reduction in the CBR value from 1.967 for plain soil to

1.687 on adding 0.2% plastic this is because the addition of

small amount of plastic into soil lead to a dispersed and

disturbed structure to soil than that it was in its compact

form. Also the optimum moisture content was maintained

the same so it also affected the decrease in the value.

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Soil Stabilisation Using Raw Plastic Bottles

PLATE LOAD TEST

Fig. 3. Load-settlement curves for various test set-ups

Table 2 Comparison of loads corresponding to 4mm

settlement

Tests done on

Settlement

(mm)

Corresponding

Load (kg)

Percentage

variation

of load

from plain

soil

Plain soil 4 440 -

Sand filled

bottles at

D/B=0.67

4 585 33%

Sand filled

bottles at D/B=1 4 680 54.5%

Bottles cut to

halves at

D/B=0.67

4 740 68.1%

Bottles cut to

halves at D/B=1 4 900 104.5%

Soil mixed with

optimum

percentage(0.6%)

of Plastic strips

4 1200 172.7%

From Table 2, it can be inferred that the load carried

corresponding to 4mm settlement is much more for soil

stabilised with plastic than that of plain soil and thus the

there is considerable increase in bearing capacity of the

soil. The plastic bottles and bottle cut to halves gave more

strength when kept at D/B=1 than that at D/B=0.67.When

load is applied, the distribution of load takes place as

shown in Fig. 4.16 It is clear that at D/B=0.67,only a

portion of the plastic bottles become effective in carrying

the load, while at D/B=1, the whole layer contributes in

taking the load. This may be the reason for the above

phenomenon noted.

Also it is found that the improvement in strength is much

more for plastic bottles cut to halves than for plastic bottles

filled with sand. Arch action may be stated as the reason

for this increase in strength.

Table 3 Variation of settlements for final load

Tests done on

Final

load

(kg)

Final

settlement

(mm)

Percentage

variation of

settlement

from plain soil

Plain soil 1344.1 18.1 -

Sand filled bottles at

D/B=0.67 1344.1 14.1 22.0%

Sand filled bottles at

D/B=1 1344.1 13.8 23.7%

Bottles cut to halves

at D/B=0.67 1344.1 13.4 26.0%

Bottles cut to halves

at D/B=1 1344.1 10.0 44.7%

Soil mixed with

optimum

percentage(0.6%) of

Plastic strips

1344.1 5.26 70.9%

From Table 3, it is evident that the final settlement for all

cases of soil stabilised with plastic is much less than that of

plain soil. Decrease in settlement points to the increase in

the bearing capacity of the soil. The factors contributing to

this increase are the position of bottles, arch action etc.

While comparing the percentage variations, it is clear that

the maximum percentage decrease in settlement is that for

the soil mixed with optimum amount of plastic strips. In

the case of soil stabilised with plastic bottles minimum

settlement is noted for the plastic bottles cut to halves at

D/B=1; this may be due to arch action.

It can also be noted that there is not much difference in

final settlements for the soil stabilised with sand filled

bottles at D/B=0.67 and D/B=1, whereas there is

considerable difference comparing the final settlements of

the soil stabilised with bottles cut to halves kept at the

respective position.

The ultimate load and corresponding settlement of the plate

is determined from the load- settlement graph plotted for

various test arrangements. It is obtained from the load and

settlement corresponding to the intersection of the tangents

drawn to the initial and final straight portions of the curve

obtained.

Table 4 Ultimate load and corresponding settlement

Tests done on Ultimate

load(kg)

Corresponding

settlement(mm)

Plain soil 360 1.6

Sand filled bottles at D/B=0.67 480 1.2

Sand filled bottles at D/B=1 560 1.6

Bottles cut to halves at

D/B=0.67 600 1.2

Bottles cut to halves at D/B=1 760 1.6

Soil mixed with optimum

percentage(0.6%) of Plastic

strips

720 0.6

491

Anas Ashraf, Arya Sunil, J. Dhanya, Mariamma Joseph, Meera Varghese & M. Veena

360

480560 600

760 720

0100200300400500600700800

Pla

in s

oil

Sa

nd

fil

led

bo

ttle

s a

t

D/B

=0

.67

Sa

nd

fil

led

bo

ttle

s a

t

D/B

=1

Bo

ttle

s c

ut

to h

alv

es

at

D/B

=0

.67

Bo

ttle

s c

ut

to h

alv

es

at

D/B

=1

So

il m

ixe

d w

ith

op

tim

um

% o

f P

last

ic …

Fig. 4. Variations of ultimate load for various test

arrangements.

1.6

1.2

1.6

1.2

1.6

0.6

00.20.40.60.8

11.21.41.61.8

Pla

in s

oil

Sa

nd

fil

led

bo

ttle

s a

t

D/B

=0

.67

Sa

nd

fil

led

bo

ttle

s a

t

D/B

=1

Bo

ttle

s c

ut

to h

alv

es

at

D/B

=0

.67

Bo

ttle

s c

ut

to h

alv

es

at

D/B

=1

So

il m

ixe

d w

ith

op

tim

um

% o

f …

Fig 5. Variations of settlement corresponding to the

ultimate load for various test arrangements.

From Table 4 and Fig. 4, it can be noted that the ultimate

load increased for the various cases of the soil stabilized

with plastic than that for the plain soil. This increase in

load carrying capacity is due to the efficiency contributed

by the bottles that was intermixed to the plain soil. The

reason for increased load for D/B=1 when compared to

D/B =0.67 is due to the variation in the distribution of load

as stated earlier. It can also be noted that when compared to

plastic bottles filled with sand, bottles cut to halves carried

much higher load; this may be due to arch action.

It can also be noted from Table 4 and Fig.5 that, though the

ultimate load carried by the soil stabilised with bottles

filled with sand and bottles cut to halves at D/B= 1 is

higher than that for the plain soil, its corresponding

settlement remained same as that for the plain soil. This is

due to the reason that in both cases the soil is being filled

similar to that of plain soil to a depth of 30cm (half the

depth of tank). Thus the immediate settlement of the soil

remains the same.

It is also seen that the ultimate load for soil mixed with

optimum amount of plastic strip is less than that of bottles

cut to halves kept at D/B= 1, but when comparing the

corresponding settlements, the former one showed only

3/8th the settlement of that of the latter case.

While comparing the test results, the arrangement which

carried the maximum load with minimum settlement is that

for soil mixed with optimum amount of plastic. At the

same time it can also be noted that soil stabilized with

bottles cut to halves kept at D/B=1 also carried

considerable load.

If we compare the quantity of waste plastic required to get

the desired results only a few bottles is sufficient when the

soil is stabilised with sand filled bottles (about 18 bottles

for our test set up) and also for soil stabilised with bottles

cut to halves (about 9 bottles for our test set-up). Whereas,

the number of bottles which is necessary to stabilise the

soil with optimum amount of plastic strips were much

higher (about 200 bottles for our test set-up). Thus the

plastic content in the soil is very much high when the strips

are used.

CONCLUSIONS

Use of plastic products such as polythene bags, bottles,

containers and packing strips etc. is increasing day by day.

The disposal of the plastic wastes without causing any

ecological hazards has become a real challenge to the

present society. Thus using plastic bottles as a soil

stabiliser is an economical and gainful utilization since

there is scarcity of good quality soil for embankments and

fills. Thus this project is to meets the challenges of society

to reduce the quantities of plastic waste, producing useful

material from non-useful waste materials that lead to the

foundation of sustainable society.

REFERENCES

1. Arora, K. R. (2004). Soil Mechanics and Foundation

Engineering. Standard Publishers Distributors.

2. Kumar, M. A., Prasad, D. S. V. and Prasadaraju, G.

V. R. (2009). Utilisation of industrial waste in flexible

pavement construction. Electronic Journal of Geotechnical Engineering, Vol. 13

3. IS: 1888(1982), Method of Load Test on Soils. Indian

Standards Institutions, New Delhi. 4. Bateni, F. (2009). Stabilisation Mechanisms of oil-

palm fruit bunch fibre reinforced silty sand.

Unpublished Ph.D. Thesis, University of Auckland. 5. Purushothama Raj, P. (2005). Soil Mechanics and

Foundation Engineering. Pearson Education.

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