Stabilization of Subgrade by Using Fly Ash

7/23/2019 Stabilization of Subgrade by Using Fly Ash

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STABILIZATION OF SUBGRADE BY USING FLY ASH RELATED TO ROAD

PAVEMENT THICKNESS DESIGN AT JALAN JAYA

GAD NG

MOHD ASHRAF BIN MOHD USSIN

A reported subm itted in partial fulfillment of the requirements for the award of the

degree of Bachelor of Clvii Engineering

Faculty of Civil Engineering Earth Resources

Universiti Malaysia Pahang

DECEMBER 2010


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A B S T R A C T

Th is project aims to study the effectiveness of adding fly ash by percentage to the

subgrade with increasing the C alifornia Bearing Ratio (C B R ) value. The fly ash will

be added to the plain soil (subgrade) by using 4 and 8 fly ash and tested by

following ASSHTO as guidance steps. California Bearing Ratio (CBR) is a

commonly used directly as to assess the stiffness modulus and shear strength of

subgrade in pavement design work. If the CB R value is increasing by adding the fly

ash to the soil

it s shown its effectiveness in increasing soil strength and vice versa

Overall, when California Bearing Ratio (CBR) value increases, the thickness of

pavement design can be reduced and subsequently the road construction of the

affected road section will be more econom ically.


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T BLE OF CONTENTS

CH PTER

ITLE

P GE

DECL R TION

DEDIC TION

CKNOW LEDGEM ENTS

v

BSTR CT

v

T BLE OF CONTENT

v

LIST OF T BLES

x

LIST OF FIGURES

x

LIST OF SYMBO LS

x

LIST OF PPENDICES xiii

NTRODUCTION

1 1 INTRODUCTION

1 2 Problem Statement

1 3 Objectives Of The Study

1 4 Scope Of Study

A


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2

L I T E R A T U R E R E V I E W

2 .1

Introduction

7

2.1 .1

oil properties

7

2 .1 .2

ddit ives

9

2.1 .3

ly Ash

9

2 .1 .4

tabilization

2 1 5

odification

2 .1 .6

echanical Stabilization

2 .1 .7

dditive Stabilization

2

2 .2 Soil classification

2

2 .3

Soil Engineering P ropert ies

3

2.3 .1

t terberg Limits

3

2.3 .2

oisture C ontent

5

2 .3 .3

he L iqu id L imi t

6

2.3 .4

he Plast ic Limit

6

2 .4

Soil

onsisten y

17

2 .5

Soil Strength

8

R E S E A RC H M E T H O D O L O G Y

3.1 Genera l

2 1

3 .2

Flow Char t

2 2

3.3

Summ ary fo r Ma te ria l & Equipment

2 3

3 .4

Labora tory Test

2 4

3.4.1

oisture Content

2 5

3.4 .2

he Liquid Lim it of Soil

2 6

3.4 .1

he Plast ic Limit of Soil

2 8

3.4 .4

article Size Analysis

3

3 4 5

tandard Proctor Test

3 2

3.4 .6

he California Bearing Ratio (CBR )

3 3

v i i


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V

ESULT AND ANALY SIS

4.1

ntroduction

3 5

4 .2

aboratory test results

3 6

4424 1 Moisture content

3 6

4.2.2 Particle size analysis

3 6

4 23

Atterberg limIt

4.2.3.1 L iquid limit

4 1

4232 Plastic limit

4 2

4.2.3.3 Plastic Index

4 3

4.2,4

tandard proctor test

4 4

4 5

alifornia bearing ratio CBR )

4 7

4 .3

umm ary of Pavement Design

5 4

4 .4

osting of T hickness Design

56

O NC LUS I O N AND REC O M M ENDAT I O NS

5 1 Conclusion

7

5 2 Recommendations

8

REFEREN ES Appendices Ant

8 7 .


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LIST

O

TABLES

T A B L E

NO

TITLE

P A G E

3 .1

M ateria l and equipm ent for soi l tes t

2 3

4 .1

Sieve analysis data

3 7

4 .2

classif icat ion of soi l sample by A ASH TO

3 9

4 .3

Liquid Limit data

4 1

4 .4

Plastic limit data

4 2

4 5

Penetra t ion value of o riginal sample

4 8

4 .6

Value of CD R for original sample

4 8

4 .7

Penetra t ion value of 4 f ly ash

5

4 .8

Value of CD R for 4 f ly ash

50

4 .9

Penetra t ion value of 8 f ly ash

5

4 . 1 0

Value of CD R for 8 f ly ash

52

4 .11

Thickness layers each sample

4 . 12

Costing for 1km soil sample

56

i x


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L I S T O F F I G U R E S

F IG U R E N O

T I T L E

P A G E

1 A

The damage of pavement

4

1 2

Site location

6

2 .1

Usa ge of fly ash at the construction site

1

2 .2

Atterberg Limit and soil volume relat ionship

1 4

2 ,3

The con sis tency s tate of soi l

1 7

2 .4

The soil core b eing s t ressed by com pressive, tensi le and

1 8

shearing

5

Graph for soi l s t rength index

2 0

3 4 1

Flow chart of methodology

2 2

3.2

The sam ple that need be inserted in the oven

2 5

3.3

Sample that be penet rated by cone penet rometer .

2 7

3 .4

The sam ples that have been rol led.

2 9

3 .5

The vibrator s ieve shaker

3

3.6

Mould for CBR test

3 4

4.1

Grain size distribution curve

3 8

4.2

The grain size distribution curve of fly ash

4 0

Penetrat ion of cone vsi m oisture content

4 3

4 .4

Com pact ion curve of the soi ls (original sample)

4 5

4.5

Com pact ion curve of the soi ls (4 f ly ash)

4 6

4 . 6 :

Com pact ion curve of the soi ls (8 f ly ash)

4 6

4.7

Graph

ad VS

Penetration for original

samp le

9

x


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x i

4.8

raph Load VS Penetration for 4 additive fly ash

4.9

raph Load VS Penetration for 8 additive fly ash

4.10

ross section of flexible pavem ent


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L I ST O F S Y M B O L S N D B B R E V I T I O N S

A A S H T O

A merican A ssociation of State H ighway and Transportat ion

Officials

A PT

Av erage daily traffic

ASTM

Am erican Society for Testing and Materials

C B R

California Bearing Ratio

C D

Consolidated drained

C U

Consolidated undrained

C U

Consolidated undrained with pore water pressure measurements

ef

equivalence factor

ESA L

Total Equ ivalent Standard Ax le Load

JK R

Jabatan Kerja }ya

L L

Liqu id limit

n

Design period (years)

Optimum moisture content

Pc

Percentage of commercial vehicles

P 1

Plastic index

PL

Plastic limit

r

Estimate the rate of annual traffic growth

SSA

Specific surface area

T

Equ ivalent thickness

U U

Unconsolidated undrained

V

he total number of comm ercial vehicles

V .

he initial yearly comm ercial vehicle traffic

Yd.max

aximum dry density

x l i


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L I S T O F P P E N D I C E S

P P E N D I X

I T L E

G E

A

ata for mois ture content

Data for

ois ture correc t ion Factor

C

ata for Co mpact ion Test

D

ata for Cal ifornia Bear ing R atio (CBR ) tes t

8

E

ata for Calculat ion thickness design

4

xli


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CHAPTER

INTRODUCTION

1 1 Background of Study

Fly ash is a by product of the pulverized coal combustion process usually

associated with electric pow er generating plants. Fly ash is a fine grained dust and is

primarily com posed of silica, alumina an d various ox ides and alkalies. It is pozzolanic in

nature and can react with hydrated lime to produces cementitious products. Braja

M.Das)

A certain type of fly ash is obtained from the burning of coal prelim inary from the

western United States to as Type C fly ash. It contains a fairly large proportion of free

lime that, with the addition of water, will react with other fly ash com poun ds to form

cem entatious products. This m ay eliminate the need to add m anufactured lime. (Braja

M.Das)


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The soil stabilization is the alteration of soil properties to impro ve the eng ineering

performance of soils. The properties most often altered are density water content

plasticity and strength. Modification of soil properties is the temp orary enha ncem ent of

sub g rade stability to ex pedite construction.

Fly ash can be an binder for stabilizing soils for highway bases

Howe ver , limi ted informa t ion exists on the reuse of high carbo n off-spec f ly ash in

construction of highway pavem ents. This is particularly important when h igh carbon fly

ash is non-cem entit ious and calcium -rich activators are required to generate p ozzolanic

react ions. Thus, there is a need to ev aluate the s t rength and st i f fness of base layers

stabilized with high carbon fly ash.

Fly ash can be used to stabilize bases or subgrades, to stabilize backfill to reduce

lateral earth pressures and to stabilize em bankm ents to impro ve slope stabili ty. Fly ash

has been used successful ly in m any projects to improve the s trength character is tics of

soils. Typical stabilized soil depths are 15 to 46 centimeters 6 to 18 inches). The primary

reason fly ash is used in soil s tabilization ap plications is to improve the com pressive and

shearing strength of soils.

For fly ash stab il ization, the selection of a m ixture of soil , f ly ash, and water

usually depends on which one wou ld provide the intended geotechnical properties on a

short- term basis . The long-term perfo rma nce of fly ash stabilized soils in the context of

field environm ents after exposure to successive different weather cycles, such as wet dry

or freeze thaw cycles is often ignored. The effect of weathering cycles on natural soils

and soils stabilized with other cementitious materials such as lime and/or cement

suggests tha t the weathering act ion m ight have a pronou nced effect on the long-term

performan ce of fly ash stabilized soils.


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1 2 Problem Statement

In Malaysia, road is an important form of com munication that connects to a

destination to other destination. In this study case, I referred at Jaya Gading road b ecause

the road condition was v ery bad and not satisfactory. Because of that, we can see many

accidents occur at Jaya Gading road.

Added the roads at Jaya Gading always have problems such as holes and damaged

on the roads and cracking pavement. Poor m aintenance of road such as potholes, water

ponding debris on the road edges, drains are not properly maintained, poor construction,

wrong design and poor road surface. Others, the consolidation of the soil also not good

and have settlement at certain soil, That s all factors can cause drivers to make surprise

manoeuvres and increase the risk of accident.

The poor condition of road could probably cause by the unstable sub g rade, The

engineering properties of sub grade need to b e taken into consideration as it influence the

ability of sub grade to resist force from the upper layer. The b ad condition of road at Jaya

G ading was the result from poor construction of the road. In site investigation of road, the

most important thing is in determination of the engineering properties of soil. In this case

study, the contractor need to confirm the soil classification in order to used the parameter

for design. Poor c lassification could be the problem of the b ad condition of road.

Commonly, the type of soil at Jaya G ading is soft soil. if the soil under the surface

layer is not good, then the upper layer will be brok en dow n. in any road in the world,

especially at Malaysia (Jaya G ading), the sub g rade layer is the critical part we m ust

obtain their strength so that there are not have any problems to the users.


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In order to avoid the surfacing course from dam age easily, a good compaction for

obtaining opt imu m m ois ture content OMC) should be done. OMC of a soil would

inf luence the pe rcentage value of California Bearing Ratio CBR). For this case study, i t

would come from a lower percentage value of CBR.

In other words, we must m ake sure that the soil under the road especially the sub

grade mu st be strong and available to use and if the so i l is not f lul f i ll of cri teria of the

JKR ro ad, we must upgrade the so il with some m ethod to m ake sure the soil is safe to be

use as road base.

.

-7

.. -. ---. --

. ,....................... .

- t

Figure 1.1:

the damage of pavement


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1 3

bjectives of Study

The ob jectives of this study are;

i.

To identify the engineering properties of soil

ii.

To know the re la tionship between pe rcentage fly ash and CBR value.

iii.

To determ ine the thickness and costing of the pavement.

1 4 Scope Of Study

This s tudy i s done based on the spec i f ic s cope in o rde r to ensu re the prec i sion o f the

study area. Besides it is also done in order to achieve the objective of the study.

There fore, , its l imit has been spe cific to specific scopes which are:

i.

Site Location

Th e locat ion of the project s ite is l im ited for dist r ic t of Jaya lading roads

Several s i tes which involved in soil embankm ent in Kuantan are being vis ited.

ii.

Scope of work

In this project , sam ple are taken from the Jaya lading site and tested at the laboratory in

order to d etermine the e ngineering propert ies of the soi l samples, laboratory test ing such

as particle size distribution moisture content and atterberg limit will assessing the


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characterist ic of the soi l samples Others laboratory test such as compaction and CB R are

important in determined the thickness of paveme nt

Figure 1 2:

Site location


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CHAPTER

LITERATURE REVIEW

2 1 INTRODUCTION

2 1 1 Soil Properties

Naturally occurring ma terials that are used for the c onstruction of all except the

surface layers of pavem ents concrete and asphalt) and that are subject to classification

test AST M D 2487) to provide a general conce pt of their engineering characteristics.

Gordo n R Sullivan 1994)

Peop le describe soil types in all kind of w ays such as he avy, light, clay and loam,

poor or go od. Soil scientist describes soil type by how m uch sand , si lt and clay a re

Present. This is called texture. It is possible to change the texture by adding different


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things. Changing texture ca n help in providing the right condition needed for plant

growth.

Sand is the largest particle in the soil. When y ou rub it, it feels rough. This is

because it has sharp edges. Sand doesn t hold m any nutrients. Silts are soil particle w hose

size is between sand and clay. Silt feels smooth and pow dery. When w et, it feels smooth

but not sticky.

Clay is the smallest of particles. Clay is sm ooth w hen dry and sticky w hen w et.

Soils high in clay content are called heavy soils. Clay also holds a lot of nutrients but

doesn t let air and w ater through it well.

Particle size has a lot to do w ith soils drainage and nutrients holding capacity. To

better understand how this big three soil, we can im agine that if a particle of sand w ere

the size of basketball, then silt w ould be the size of a baseball, and clay would be the size

of a golf ball. Line them up, and w e can see how these particle compare in size.

onstruction of roadways over soft subgrade is one of the most common

problems for highw ay construction in many parts of the w orld as w ell as in our country,

M alaysia. The usual approach to soft subgrade stabilization is to remove the soft soil, and

replace it with a stronger m aterial of crushed rock . The high cost of replacement has

caused highw ay agencies to evaluate alternative methods of highw ay construction on soft

subgrade.

O ne approach is to use fly ash to stabilize the soft sugared. The strength values of

the soil fly ash mixtures w ere evaluated to characterize the performance of stabilized soil


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W

as a road subbase. Unconfined comp ression strength and California bearing ratio CB R)

tests were performed to determine the strength properties of the soil fly ash mixtures and

the optimum mixture contents for construction.

2 1 2 Additives

Manu factured com me rcial products that, wh en added to the soil in the proper

quantities, improv e some engineering characteristic, and plasticity Gordon R . Sullivian,

1994 ). Additives addressed in this manual are limited and only focus on the fly ash.

2 3 Fly Ash

Fly ash is one of the m ost plentiful and versa tile industrial by-prod ucts. It is

generated in large q uantities as a b y-product of burning co al at electric power plants;

Class C fly ash is usually recy cled as an en gineering material to take advantage of i ts

pozzo lanic characteristics.

his type of fly ash provides the opportunity for applications where other

activators would not be required. It offers more eco nomical alternatives for a w ide range

of soil stabilization ap plications. The potential for using fly ash in soil stabilization has

increased significantly in Malaysia due to increased av ailability and the introduction of

new environmental regulations that encourage the use of fly ash in geotechnical


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1 0

applications w hen it is environmen tally safe. Results of various investigations showed

that soil stabilization with Class C fly ash without any other ac tivator is encouraging. The

improve d engineering properties of fly ash stabilized soil are also reported Edil et al.,

2000

200 2; Senol et aL 200 3; Turner, 1997)

Figure 2 1:

usage of fly ash at the construction site

Fly ash consists primarily of oxides of silicon aluminum iron and calcium.

Magnesium, potassium, sodium, titanium, and sulfur are also present to a lesser degree.

W hen used as a m ineral admixture in concrete, fly ash is classified as either Class C or

Class F ash based on its chemical com positions Fineness of fly ash is most closely related

to the operating condition of the coal crushers and the grind ability of the coal itself, A

coarser gradation can result in a less reactive ash and could contain higher carbon

contents. Limits on fineness are addressed by ASTM and state transportation department

specifications,


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2 1 4 Stabilization

Stabilization is the proce ss of blending and m ixing with a soil to improve c ertain

properties of the soil. The process m ay include the blending o f soil to achieve a desired

gradation or the m ixing of com mercially available additives that ma y alter the gradation,

texture or plasticity, or act as a binder for cem entation of the soil. Gord on R. Sullivan,

1 9 9 4

2 1 5 M odification

Modification refers to the stabilization process that results in improvem ent in

some properties of the so il but thus not by de sign result in a significant increase in soil

and durability W illiam

Wildman, 1981)

21 6 Mech anical Stabilization

Mechanical stabilization is accomp lished by mixing or blending soil of two or

more gradations to obtain a m aterial meeting the required specification. The soil blending

may take place at the construction site, a central plant, or a borrow area. The blended

material is then spread and com pacted to required densities by the conve ntional means.

Gordon

R

Sullivan, 1994)


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2

2 1 7

dditive Stabilization

Ad ditive stabilization is achieved b y the addition of proper percentag e of cemen t,

lime, fly ash, bitum en, or com bination of these m aterials to the soil. The selection of type

and determ ination of the percen tage of addit ive to be used is depending upo n the soil

classification and the deg ree of improvem ent in soil quality desired (Gordon R . Sullivan,

1994) .

Gen erally, smaller amounts of ad ditives are required whe n it is s imply d esired to

mo dify soil properties such as gradation, workab ility, and plasticity. W hen it is desired to

improve the strength and durability significantly, larger quantities of additives are used.

After the additive has been m ixed with the soil, spreading and comp action are achieved

by conventional means.

2 .2

oil Classification

Soil classification is a way of systematically categorizing soils according to their

probab le engineering c harac teristics. The c lassification of a soil is based on its particle

distribution and, if the soil isfine-grained, on its plasticity (LL an P1 ). The m ost widely

used classification systems used in road engineering are the unified soil classification

system, AASHTO classification and British Standard Classification. Soil classification

should only be regard ed as a m eans of obtaining a general idea of soil behavior and i t

should nev er be used as a su bstitute for detailed investigation of soil properties. (Richard

Robinson Bent Thagesen, 2004)


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3

2.3

oil Engineering Prop erties

To hav e an understand ing of soil action, an engineer m ust be familiar with certain

basic soi l propert ies. We are al l fam iliar with the ba sic propert ies of o ther engineering

materials such as steel wood and concrete. A soil engineer must have familiar

know ledge relative to soil (Paul H. Wright/Karen K . Dixon, 2004).

2.3.1 Atterberg Limits

The liquid limit may be defined as the minimum m oisture content at which the

soil will flow u nder the a pplication of a very sma ll shear force. At this moisture content

the soil is assum ed to behave practically as a liquid. The plasticity limit ma y be defined

in general term as the minimu m m oisture content at which the soi l remains in a plast ic

cond ition. This lower lim it of plasticity is rather arbitrarily defined, and the plastic limit

ma y be further describe as the lowest mo isture content at wh ich the soil can be rolled

into a thread of 1/8 in. (3.2mm ) diameter w ithout crum bling. (Paul h. Wright/Karen k.

Dixon, 2004)

The plastic index P1)

of a soi l is defined as the num erical difference between

the liquid and plastic limits. It thus indicates the range of m oisture content over w hich the

soil is in a plastic condition. Sandy so il and silts, particularly those of the rock-flour type,

have ch aracteristically low PIs, wh ile clay soil show s high value of the plasticity index .


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4

Ge nerally speaking, soils that are highly plastic as indicated by a high value of the

plasticity index are a lso highly

com pressible. It is also ev ident that the p last ic index is

measure of cohesiveness with a high value of the P1 indicating a high degree of

cohesion; So ils that do not have a plastic limits such as cohe sionless sands are repo rted as

being non plastic (NP). (Paul h, wright Karen k. Dixon 2004)

volum

Water on ten t

Figure 2 2:

Atterberg L imit and soil volume relationship

Stabilization of Subgrade by Using Fly Ash

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