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STUDY ON THE GEOTECHNICAL PROPERTIES OF FLY ASH AND ITS APPLICATION IN SOFT SOIL STABILIZATION
Emilliani Anak Geliga
TA Bachelor of Engineering with Honours 455 (Civil Engineering) F55 2009 F53 2009
UNIVERSITI MALAYSIA SARAWAK
RI 3a BORANG PENGESAHAN STATUS TESIS / LAPORAN
JUDUL: STUDY ON THE GEOTECHNICAL PROPERTIES OF FLY ASH AND ITS APPLICATION IN SOFT SOIL STABILIZATION
SESI PENGAJIAN : 2008 / 2009
Saya EMILLIANI ANAK GELIGA
mengaku membenarkan tesis / Laporan* ini disimpan di Pusat Khidmat Maklumat Akademik,
Universiti Malaysia Sarawak dengan syarat-syarat kegunaan seperti berikut:
I. Tesis / Laporan adalah hakmilik Universiti Malaysia Sarawak
2. Pusat Khidmat Maklumat Akademik, Universiti Malaysia Sarawak dibenarkan membuat salinan
untuk tujuan pengajian sahaja 3. Pusat Khidmat Maklumat Akademik, Universiti Malaysia Sarawak dibenarkan membuat pendigitan
untuk membangunkan Pangkalan Data Kandungan Tempatan
4. Pusat Khidmat Maklumat Akademik, Universiti Malaysia Sarawak dibenarkan membuat salinan tesis / laporan ini sebagai pertukaran bahan antara institusi pengajian tinggi
5. * sila tandakan (�) di kotak yang berkenaan
SULIT** (mengandungi makulamat yang berdarjah keselamatan atau kepentingan seperti termaktub dalam AKTA RAHSIA RASMI 1972)
V/
TERHAD (mengandungi maklumat terhad yang telah ditentukan oleh Organisasi / badan di mana penyelidikan dijalankan)
TIDAK TERHAD*
Disahkan
Q) 6
(TAN AT GA ENULIS) (TANDATAN AN PENYELIA) Alamat tetap : 1182, Lorong 3, Jln Pgn
Abu Bakar, Rpr Kidurong, Tarikh: 97000 Bintulu, Sarawak `
Tarikh : 18 May 2009
( at n: m: *I esis l. aporan dimaksudkan sebagai tesis hagi Ijazah Doktor Falsafah, Sarjana dan Sarjana Muda
"Jika I esis I aporan ini S1111 atau TLRHAD, sila lampirkan surat daripada pihak berkuasa organisasi
Ixrkenaan dengan menyatakan sekali schab dan tempoh tesis laporan ini perlu dikelaskan sebagai SIILIT atau
I IRIIAD
Cým
Supervisor Approval
The following Final Year Project Report:
Title STUDY ON THE GEOTECHNICAL PROPERTIES OF FLY ASH
AND ITS APPLICATION IN SOFT SOIL STABILIZATION
Author : EMILLIANI ANAK GELIGA
Matric : 13982
Has been read and approved by:
gis. {ý ýý Cik Dayangku Salma Bt Awang Ismail Date
rusat Khidmat Maklumat Akademik UNTVESlT! MALAYSIA SARAWAK,
STUDY ON THE GEOTECHNICAL PROPERTIES OF FLY ASH AND ITS APPLICATION IN SOFT SOIL STABILIZATION
EMILLIANI ANAK GELIGA
This report is submitted to
Faculty of Engineering, Universiti Malaysia Sarawak
in partial fulfillment of the requirements
for the award of the degree of Bachelor of Civil Engineering 2009
-! edicated to o7mdda (Fhiany oýi'ui O3ierr and Codrya ak
Z°hank peu fr everpthiny. ..
UNIVERSITI MALAYSIA SA AW,
TABLE OF CONTENT
Content
Acknowledgement
Abstract
Abstrak
List of Tables
List of Figures
List of Nomenclatures
Chapter 1 INTRODUCTION
1.1 Background of Study
1.2 Problem Statement
1.3 Objective of Study
1.4 Scope of Study
Chapter 2 LITERATURE REVIEW
2.1 General
2.2 Overview of Fly Ash
2.2.1 Classification of Fly Ash
2.2.2 Fly Ash in Construction Industry
2.3 Physical Properties of Fly Ash
2.3.1 Particle Size Distribution
2.3.2 Atterberg Limits
2.3.3 Specific Gravity
2.3.4 Loss on Ignition
Page
ii
111
iv
V
VI
ix
1
2
2
3
4
4
7
8
10
10
11
13
14
2.4 Chemical Properties of Fly Ash
2.5 Mechanical Properties
2.5.1 Compaction Characteristics
2.5.2 Compressive Strength
2.6 Hydration of Fly Ash
2.7 Soil Stabilization
2.7.1 Mechanical Method
2.7.2 Additive Method
2.7.3 Modification Method
2.7.4 Selection of Stabilizer
14
17
18
18
19
21
22
22
23
2.7.5 Application of Fly Ash as Soil Stabilizer 23
2.7.6 Performance Record 24
2.8 Advantages of using Fly Ash in soil stabilization 27
Chapter 3 METHODOLOGY
3.1 Introduction 29
3.2 Literature Review 31
3.3 Data Collection
3.3.1 Test Materials and Laboratory Testing 31
3.3.2 Atterberg Limits 31
3.3.3 Specific Gravity 34
3.3.4 Hydrometer Analysis 35
3.3.5 Standard Proctor Test 36
3.3.6 Unconfined Compressive Test (UCT) 36
3.3.7 Data Analysis 37
3.3.8 Conclusion and Recommendations 37
Chapter 4 RESULT ANALYSIS AND DISCUSSIONS
4.1 Laboratory Tests 38
4.2 Sample Classifications Tests of Fly Ash Sample 38
4.2.1 Atterberg Limits 39
4.2.2 Specific Gravity 40
4.2.3 Particle Size Distribution Test 41
4.2.4 Summary of Finding for Fly Ash Sample 42
4.3 Classification Tests on Clay Sample
4.3.1 Atterberg Limits 42
4.3.2 Specific Gravity 45
4.3.3 Particle Size Distribution 45
4.3.4 Summary of Finding for Clay Sample 46
4.4 Atterberg Limits of Fly Ash and Clay Sample Mixes 47
4.5 Mechanical Test
4.5.1 Standard Proctor Test 49
4.5.2 Unconfined Compressive Test 52
4.5.3 Summary of Findings for Mechanical Properties of Clay and Fly Ash Sample 54
Chapter 5 CONCLUSIONS AND RECOMMENDATIONS 55
5.1 Conclusions 55
5.2 Recommendations 57
REFERENCES
APPENDIX A Atterberg Limits Result Data
APPENDIX B Specific Gravity Determination Result Data
APPENDIX C Standard Proctor Test Result Data
APPENDIX D Unconfined Compressive Test Result Data
ACKNOWLEDGEMENT
In preparing this thesis, challenges are met and solved. I would like to bestow my
greatest appreciation to my thesis supervisor, Miss Dayangku Salma Awang Ismail,
for encouragement guidance, friendship and perseverance guidance all throughout
until the final.
I am so indebted to the librarians in Centre for Academic Information System (CAIS)
for their assistance in supplying relevant materials for my thesis.
My sincere appreciations extend to Haji for his supervision and guidance in the
Geotechnical Engineering Laboratory, Faculty of Engineering, Civil Engineering.
The supports from family and friends are always in my heart.
ii
ABSTRACT
Soil stabilization had become a major issue in construction engineering and the
researches regarding the effectiveness of using industrial wastes as a stabilizer were
at a fast pace. This study is focused on suitability of the local fly ash to be
implemented in the local construction industry for the stabilization of local soft soil
specifically in such a way to minimize the waste to be disposed to the environment
which can pollute the environment and cause health hazards to the public. The basic
geotechnical properties of local fly ash were determined in order to understand its
behaviors. The study shows the liquid limit of fly ash and clay mixture of 0%, 5%,
10%, 15% and 20% by dry weight of clay result in a declined value. The effects of
fly ash addition with proportion of 0%, 60%, and 80% by soil dry weight also been
investigated. The shear strength of cured sample tested was decreasing when amount
of fly ash governed 80% of the total weight of mixture within the limitation based on
the dry density and optimum moisture content of the fly ash.
III
ABSTRAK
Penstabilan tanah telah menjadi satu isu utama dalam kejuruteraan pembinaan dan
pelbagai kajian mengenai keberkesanan menggunakan bahan buangan industri
sebagai penstabil semakin mendapat perhatian. Kajian membentangkan secara
ringkas kesesuaian abu terbang tempatan untuk digunakan dalam industri pembinaan
tempatan sebagai salah satu langkah yang di ambil untuk mengurangkan
pembuangan abu terbang ke alam sekitar yang mana boleh mencemarkan
persekitaran dan memjejaskan kualiti kehidupan. Sifat - sifat geoteknikal abu
terbang tempatan dikaji bagi menentukan ciri - ciri dan sifatnya. Had limit cecair
campuran abu terbang dan tanah liat dengan peratus 0%, 5%, 10%, 15% dan 20%
berdasarkan jisim kering tanah liat menunjukkan penurunan dalam had limit cecair.
Kesan penambahan peratusan abu terbang dengan nisbah peratusan sebanyak 0%,
60%, dan 80% berdasarkan jisim kering tanah juga di kaji. Kekuatan tanah yang
distabilkan menunjukkan penurunan pada peratusan abu terbang sebanyak 80%
berdasarkan ketumpatan kering abu terbang tempatan.
iv
LIST OF TABLES
Table Page Number
2.1 Physical Properties of Fly Ash
2.2 Chemical Characteristics of Fly Ash
2.3 Geotechnical Properties of Fly Ash
4.1 Basic Geotechnical Properties of Fly Ash
4.2 Basic Geotechnical Properties of Clay Sample
4.3 Results of Atterberg Limits for Fly Ash and Clay
Sample Mixes
4.4 Summary of data of Unconfined Compressive
Tests
4.5 Summary of Findings for Mechanical Properties of
Clay and Fly Ash Sample
5.1 Summary of Results
10
15
17
42
46
47
53
54
55
V
4.6 Chart of particle size distribution for pulverized fly ash
4.7 Chart of Penetration of Cone against Moisture Content Of Different Percentage Of Fly Ash
4.8 Dry Density versus Moisture Content of Fly Ash Sample
4.9 Dry Density versus Moisture Content of clay sample
4.10 Stress - Strain Characteristic
4.11 Maximum Axial Stress of different percentage of fly ash and clay mixes.
45
48
49
50
52
53
vii
LIST OF FIGURES
Figure Page Number
2.1 Method of Fly Ash Transfer 5
2.2 Production of fly ash in a dry-bottom utility boiler 6
with electrostatic precipitator.
2.3 Fly ash particles at 2,000x magnification
2.4 Consistency Limit
3.1 Flow Chart of Research Activities
3.2 Cone Penetrometer
3.3 Rolling Threads of Sample
11
13
30
33
34
3.4 Volumetric Flask 34
3.5 Sedimentation of Clay after 24 Hrs
3.6 Sedimentation of Fly Ash after 24 hrs.
3.7 Mold and Baseplate
3.8 Compactor or Hammer
3.9 The Sample Failed due to the axial load exerted by the apparatus
4.1 Chart of Cone Penetration against Moisture Content of Fly Ash
4.2 Plasticity Chart indicating region of fly ash
4.3 Chart of particle size distribution for fly ash
4.4 Chart Cone Penetration against Moisture Content of Clay Sample
4.5 Plasticity Chart indicating region of fly ash
35
35
36
36
36
39
40
41
43
44
VI
LIST OF NOMENCLATURES
Am
mm
ml
cm3
kg
CBR
N
d
PI
LL
PL
PVC
UCT
Micrometer
millimeter
milliliter
Centimeter Cube
Kilogram
California Bearing Ratio
Newton
Depth of Penetration
Plasticity Index
Liquid Limit
Plastic Limit
Polyvinyl Chloride
Unconfined Compressive Test
ix
CHAPTER 1
INTRODUCTION
1.1 Background Of Study
Civil engineering projects located in areas with soft or weak soils have
traditionally considered improving soil properties by using cement and lime. Use of
fly ash as a ground improvement soil admixture, when found viable, will be effective
in terms of cost and a good approach to the environment to preserve and minimize
wastages. This study is performed to study the geotechnical properties of fly ash for
its application in the stabilization of soft soil. The geotechnical properties of fly ash
will be evaluated with various laboratory tests to investigate the feasibility of using
fly ash in soft soil stabilization.
1
1.2 Problem Statement
Constructions over soft soil are one of the most frequent problems in many parts
of the world. The typical approach to soil stabilization is to remove the soft soil, and
substitute it with a stronger material of crushed rock. Due to the enormous cost of
replacement, alternative methods to the problems are assessed.
The study of using coal combustion residues, fly ash, is carried out to observe
the effectiveness of its addition on stabilization of soft soil. This is one of the
approaches to overcome the increasing amount of solid waste generated by the
population. As land is a very valuable commodity and landfills are fast diminishing,
the disposal of the ash generated from solid waste incineration poses increasingly
difficult problems for the municipalities. A feasible solution to the disposal problems
would be the reuse of solid waste ash for civil engineering applications. A research
study of the geotechnical properties of the incinerator fly ash derived from solid
waste incineration is investigated.
1.2 Objective Of Study
The objectives of the study are:
i. To determine the geotechnical properties of fly ash.
ii. To investigate the effects of fly ash addition for strength of
stabilized soft soil.
2
1.4 Scope Of Study
Scope of this study is to analyze the consequences of the application of fly ash
in soft soil stabilization. It covers methods for determining the geotechnical
properties of fly ash to assess its suitability for soft soil stabilization. The shear
strength of cured sample will be tested within the limitation based on the dry density
and optimum moisture content of the fly ash. The sample of local clay is obtained
from Simpang Tiga, Kuching while fly ash is taken from Sejingkat Thermal Plant,
Kuching.
3
CHAPTER 2
LITERATURE REVIEW
2.1 General
A review of existing literature on the geotechnical properties of fly ash has been
discussed in this chapter.
2.2 Overview of Fly Ash
Fly ash is one of the most plentiful and versatile industrial by-products. It is
generated in vast quantities as a by-product of burning coal at electric power plants
(Senol et al., 2006). Electric utility companies in many parts of the world generate
electricity by burning coal which generate voluminous amounts of fly and bottom
ash. Fly ash generated by coal combustion based power plants typically fall within
the ASTM fly ash classes C and F (Reyes and Pando, 2007).
Fly ash is produced by coal-fired electric and steam generating plants.
Typically, coal is pulverized and blown with air into the boiler's combustion chamber
4
ý'^: Khiji!::, i ; v1ak? llwzt Aildeutilc t, , VERSITI MALAYSIA SAPAWAK
where it immediately ignites, generating heat and producing a molten mineral
residue. Boiler tubes extract heat from the boiler, cooling the flue gas and causing the
molten mineral residue to harden and form ash. Coarse ash particles, referred to as
bottom ash or slag, fall to the bottom of the combustion chamber, while the lighter
fine ash particles, termed fly ash, remain suspended in the flue gas. Prior to
exhausting the flue gas, fly ash is removed by particulate emission control devices,
such as electrostatic precipitators or filter fabric bag houses as indicated in figure
2.1(FHWA, 2006).
Coal Source
Coal Pulverizer
Storage
v Dry Fly Ash to Utilization
-º
ý
Boiler -10
ý----
Conditioned Fly Ash to
Utilization or Disposal
Electrostatic Precipitator or Baghouse
Transfer System
Pond
Ponded Ash Excavated and Stockpilled.
i
Utilization
Figure 2.1: Method of Fly Ash Transfer (FHWA 2006)
5
Fly ash consists of inorganic matter present in the coal that has been fused
during coal combustion. This material is solidified while suspended in the exhaust
gases and is collected from the exhaust gases by electrostatic precipitators. Since the
particles solidify while suspended in the exhaust gases, fly ash particles are generally
spherical in shape (Ferguson et. al., 1993). Fly ash particles those are collected in
electrostatic precipitators are usually silt size (0.074 - 0.005 mm). Figure 2 shows the
general flow diagram of fly ash production in a dry-bottom coal-fired utility boiler
operation.
Figure 2.2: Production of fly ash in a dry-bottom utility boiler with electrostatic
precipitator.
Fly ash is a hazardous mineral residue resulting from the combustion of coal
and its disposal causes environmental pollution. The bulk utilization of fly ash is
possible by stabilizing the soils using fly ash in the construction of structures such as
embankments, pavements, and earth retaining structures where soil is used as a
construction material. It is also involved in typical highway engineering applications
6
include: Portland Cement Concrete (PCC), soil and road base stabilization, flowable
fills, grouts, structural fill and asphalt filler (FHWA, 2006).
Making a more productive and helpful use of fly ash would have considerable
environmental benefits, reducing air and water pollution as well. Increased use as a
partial cement or lime replacement would also represent savings in energy because
fly ash has been called a high-energy-based material (Hausmann, 1990). Fly ash
utilization, especially in concrete, has significant environmental benefits including
the following (FHWA, 2006):
1) Increasing the life of concrete roads and structures by improving concrete
durability.
2) Net reduction in energy use and greenhouse gas and other adverse air
emissions when fly ash is used to replace or displace manufactured cement.
3) Reduction in amount of coal combustion products that must be disposed in
landfills.
4) Conservation of other natural resources and materials.
2.1.1 Classification of Fly Ash
Two classes of fly ash are defined by ASTM C618: Class F fly ash and Class C
fly ash. Class F fly ash is normally produced from burning anthracite or bituminous
coal and contains small amounts of lime. This fly ash has pozzolanic properties,
which by itself possesses little or no cementitious value, but in the presence of
7
moisture, chemically reacts with lime at ordinary temperatures to form cementitiuos
compound (Chu and Kao, 1993).
Class C fly ash is normally produced from burning sub bituminous or lignite
coal and usually contains a significant amount of lime along with pozzolanic
materials (Haussman, 1990). This type of fly ash may show both pozzolanic and
cementitious properties (Senol et. al., 2002).
2.1.2 Fly Ash in Construction Industry
India produces about 70 million tons of coal ash per year from burning about
200 million tons of coal per year for electric power generation. Coal-ash
management poses a serious environmental problem for India and requires a mission-
mode approach. Considerable research and development work have been undertaken
across the country towards confidence building and developing suitable technologies
for disposal and utilization of fly ash in construction industries. At present about
10% ash is utilized in ash dyke construction and land filling (a technology developed
and pioneered at IIT Kanpur) and only about 3% of ash is utilized in other
construction industries. This is very much in contrast with 80% or more fly ash used
in developed countries for the manufacture of bricks, cellular concrete blocks, road
construction, land fill application, ceramics, agriculture, insulating bricks, recovery
of metals and cenospheres and dam constructions (Prabakar et. al., 2004).
Several pilot projects were undertaken in recent years to demonstrate the bulk
utilization of fly ash specifically for Indian conditions. Also, it has been successfully
demonstrated that fly ash can be utilized in major construction projects such as dams,
8
