granulated blast furnace slag in structural lightweight panel for...

GRANULATED BLAST FURNACE SLAG IN STRUCTURAL LIGHTWEIGHT PANEL FOR

HOUSING

ZAID SHAKER MAHMOOD

UNIVERSITI SAINS MALAYSIA

2016

GRANULATED BLAST FURNACE SLAG IN STRUCTURAL LIGHTWEIGHT PANEL FOR

HOUSING

by

ZAID SHAKER MAHMOOD

Thesis submitted in fulfillment of the requirements for the degree of

Doctor of Philosophy

August 2016

ii

ACKNOWLEDGEMENT

I offer my greatest gratitude to my supervisor Dr. Norizal Noordin for his

guidance, time and patience through each step of the way. He has supported me

throughout my thesis with his knowledge whilst allowing me the room to work in my

own way. I attribute this work to his encouragement, effort and without him this

thesis would not have been completed or written. I would also like to thank and show

my deepest appreciation to my Co-supervisor Assoc. Prof. Dr. Hanizam Awang for

the effort and time that she has give in this research.

I would also like to show my greatest gratitude to Universiti Sains Malaysia

for giving me the opportunity of obtaining my Ph.D. degree. Thus, giving me the

chance of having better opportunities in life. I want to thank my dearest friends for

their help, encouragement and feedback and they are Muhammed Zuhear Al-mulali,

Muhammed Abu AlMa’ali, Raith Zeher and Ng Phei Li. Without you all this work

would not have happened. I want to show my deepest appreciation to my family

members who stood by me during the best and worst times throughout my studying

period.

Last but not least, to my mother and father, in-laws, my wife Hala, my

daughters Jude and Zuha. Each one of you has sacrificed the most for me to achieve

what I have achieved. I am deeply indebted to you and I hope that this humble work

would repay a tiny portion of what you have done for me. Thank you is something

small compared to what you have sacrificed. You have always been that light at the

end of the tunnel given me hope and inspiration to be a better, more loving person. If

it was not for your unconditional love, sacrifice and continuous prays this humble

work would not have seen the light. Therefore I thank you from the bottom of my

heart.

iii

TABLE OF CONTENTS

ACKNOWLEDGEMENTS ii

TABLE OF CONTENTS iii

LIST OF TABLES ix

LIST OF FIGURES xiv

LIST OF EQUATIONS xx

LIST OF ABBREVIATIONS xxi

ABSTRAK xxii

ABSTRACT xxiv

CHAPTER 1: INTRODUCTION

1.1 Introduction 1

1.2 Problem statement 3

1.3 Objectives of the study 6

1.4 Significant of the study 7

1.5 Scope of the study 8

1.6 Thesis layout 8

CHAPTER 2: LITERATURE REVIEW

2.1 Introduction 11

2.2 Foam concrete 11

2.3 Materials utilised in foam concrete 13

2.4 Properties of foam concrete 17

2.4.1 Consistency and stability of foam concrete 17

iv

2.4.2 Density 20

2.4.3 Compressive strength 22

2.4.4 Flexural and splitting tensile strength 29

2.4.5 Ultrasonic pulse velocity 31

2.4.6 Drying shrinkage 32

2.4.7 Intrinsic permeability 36

2.4.8 Water absorption 38

2.4.9 Carbonation depth 40

2.4.10 Porosity 41

2.5 Granulated blast furnace slag (GBS) 44

2.6 Ground granulated blast furnace slag (GGBS) 49

2.7 Properties of GGBS 51

2.7.1 Chemical composition of blast furnace slag 51

2.7.2 Physical characteristics of blast furnace slag 53

2.8 Hydraulic activity of GGBS 55

2.9 GGBS indexing 57

2.10 Properties of concreting materials containing GGBS 57

2.10.1 Workability 58


2.10.3 Microstructure and porosity 61


2.10.5 Flexural and splitting tensile strength 70

2.10.6 Ultrasonic pulse velocity (UPV) 75

2.10.7 Unit weight 78

2.10.8 Shrinkage behaviour 79

v



2.11 Pre-cast concrete wall panel 87

2.12 Classes of wall panels 87

2.12.1 Non- load bearing wall panels (cladding) 87

2.12.2 Load bearing wall panels 88

2.13 Types of wall panels 88

2.14 Lightweight foam concrete wall panels 88

2.15 Conclusion 95

CHAPTER 3: METHODOLOGY

3.1 Introduction 97

3.2 Preliminary study 97

3.2.1 Phase one 99

3.2.2 Phase two 100

3.3 Materials 102

3.3.1 Physical properties of binding material 102

3.3.2 Chemical characteristics of binding material 106

3.3.3 Fine aggregate 108

3.3.4 Water 109

3.3.5 Water reduction agent (PS-1) 110

3.3.6 Foaming agent 111

3.4 Mix constituents 111

3.5 Mixing procedure and curing method 114

3.6 Testing programme 115

vi

3.6.1 Mechanical properties 115

3.6.2 Physical properties 116

3.6.3 Durability 116

3.7 Testing programme for wall panels 118

3.8 Computer analysis using STAAD Pro 119

3.8.1 Modeling mode 119

3.8.2 Analysis and design 119

3.8.3 Post processing mode 120

CHAPTER 4: RESULTS AND DISCUSSIONS

4.1 Introduction 121

4.2 Fresh properties 121

4.3 Hardened properties 129


4.3.2 Flexural strength 136

4.3.3 Splitting tensile strength 144

4.3.4 Oven dry density 151

4.3.5 Ultrasonic pulse velocity (UPV) 159

4.3.6 Drying shrinkage 167

4.3.7 Porosity 172




4.4 Optimum GBS mix 199

4.5 Conclusion 201

vii

CHAPTER 5: DEVELOPMENT OF LIGHTWEIGHT PRECAST LOAD

BEARING WALL


5.2 Design concept 203

5.3 Load determination and wall structural design 206

5.4 Mould fabrication 210

5.5 Steel fabrication 212

5.6 Mixing procedure and curing 213

5.7 Preparation and testing procedure 215

5.8 Experimental results 218

5.9 The correlation between walls with 1.8 and 2.8 meter heights 224

5.10 Conclusion 229

CHAPTER 6: CONCLUSION AND FUTURE WORK


6.2 Effect of GBS inclusion on fresh properties of foam concrete 231

6.3 Effect of GBS inclusion on the mechanical properties of foam

concrete

232

6.4 Effect of GBS inclusion on the physical properties of foam

concrete

233

6.5 Effect of GBS inclusion on the durability of foam concrete 234

6.6 Optimum GBS foam concrete mix 234

6.7 Precast lightweight load bearing wall 235

6.8 Future work 237

viii

REFERENCES 238

LIST OF PUBLICATIONS 256

APPENDICES

ix

LIST OF TABLES Page

Table 2.1 Utilization of foam concrete in various applications. 13

Table 2.2 Utilization of various materials as additives and admixtures in

constituents of foam concrete.

16

Table 2.3 Compressive strength of foam concrete determined by other

studies

28

Table 2.4 Splitting tensile strength determined in previous studies 30

Table 2.5 Flexural strength determined in previous studies 31

Table 2.6 Drying shrinkage of foam concrete determined in previous

studies

36

Table 2.7 Cooling methods of blast furnace slag 47

Table 2.8 Examples of GBS utilization in the construction industry 49

Table 2.9 Recent projects utilised GGBS as cement replacement in

Malaysia.

50

Table 2.10 Range of chemical constituents of GGBS based on BS 6699 and

BS EN 15167-1.

51

Table 2.11 The range of oxide in GGBS based on ACI report. 52

Table 2.12 Chemical composition of GGBS mentioned in previous

researches

52

Table 2.13 Physical properties of GGBS that mentioned in previous

researches

53

Table 2.14 Water Absorption (as weight %) with deferent curing and age at

various GGBS replacement levels.

60

x

Table 2.15 Water absorption (as weight%) at various GGBS replacement

level and ages (with and without SiO2).

61

Table 3.1 GBS indexing. 100

Table 3.2 Trial mixes with the results for the compressive strength at 7 and

28 days.

101

Table 3.3 Physical properties of the binding materials. 103

Table 3.4 Particle size distribution of the binding materials. 104

Table 3.5 Chemical composition of binding materials (wt. %). 107

Table 3.6 Typical properties of super plasticiser (PS-1). 110

Table 3.7 General properties of the foaming agent and aqueous foam. 111

Table 3.8 Mix constituents of foam concrete for three series. 113

Table 4.1 The actual water demand, mortar density, foam required and

actual foam quantity for all mixes in three series

122

Table 4.2 Fresh density, hardened density, consistency and stability of

foam concrete

128

Table 4.3 Compressive strength of the three series through the age 130

Table 4.4 Strength development of foam concrete mixes with GBS and

GGBS as 7 days the benchmark

135

Table 4.5 The ratio of strength at the age of 28 and 180 days for mixes

containing GBS and their correspondent GGBS mixes

136

Table 4.6 Flexural strength of foam concrete for three series with the ages

(MPa)

137

Table 4.7 The ratio of flexural to compressive strength at the age of 28 and

90 days for the three series

142

xi

Table 4.8 Relation between flexural and compressive strength at 28 days

for mixes with GBS and GGBS presented as R2 and equations

144

Table 4.9 Splitting tensile strength of foam concrete for different cement to

sand ratio through the ages

145

Table 4.10 The ratio of tensile to compressive strength at the age of 28 and

90 days for all mixes

150

Table 4.11 Relation between tensile splitting strength and compressive

strength at 28 days for mixes with GBS and GGBS presented as

R2 and equations

151

Table 4.12 Oven dry density of the three series with age (kg/m3) 152

Table 4.13 The ratio of demoulding to oven dry density for the three series

at all ages

155

Table 4.14 The correlation between compressive strength and oven dry

density at 28 days for mixes with GBS and GGBS presented as

R2 and equations

157

Table 4.15 The ratio of compressive strength to oven dry density at 28, 90

and 180 days for three series (× 10-3)

158

Table 4.16 Ultrasonic pulse velocity of three series (m/s) through the age 159

Table 4.17 The correlation between compressive strength and ultrasonic

pulse velocity at 28 days for mixes with GBS and GGBS

presented as R2 and equations

165

Table 4.18 The correlation between UPV and oven dry density at 28 days

for mixes with GBS and GGBS presented as R2 and equations

167

Table 4.19 Drying shrinkage readings for all mixes with age (10-4) strain 168

Table 4.20 The porosity of the three series as a function of age 173

xii

Table 4.21 The correlation between Porosity and compressive strength at 28

days for mixes with GBS and GGBS presented as R2 and

equations

180

Table 4.22 The correlation between Porosity and oven dry density at 28


equations

181

Table 4.23 Water absorption (weight %) of the three series as a function

with age

183

Table 4.24 The correlation between water absorption and Porosity and at 90


equations

189

Table 4.25 Intrinsic Permeability for three series through the age ×10-11 (m2) 190

Table 4.26 The correlation between intrinsic permeability and Porosity and

at 90 days for mixes with GBS and GGBS presented as R2 and

equations

193

Table 4.27 Carbonation depth as a function of age for three series 194

Table 4.28 The correlation between carbonation depth and intrinsic

permeability at 90 days for mixes with GBS presented as R2 and

equations

199

Table 4.29 The comparison between control mixes and 30% GBS foam

concrete in series I and II

201

Table 5.1 The total load applied on ground floor wall panel 207

Table 5.2 The value of the variables that are used in equation 5.1 and

results with 0.9 m width for walls with different heights.

208

Table 5.3 Design and ultimate shear capacity for bolt 210

xiii

Table 5.4 The compressive strength and density for the mix used in casting

the ribbed panels at 7 and 28 days of age

214

Table 5.5 The Coordinates of the strain gauges and LVDT (mm) 217

Table 5.6 Results comparison between the present study and previous foam

concrete wall panels

219

Table 5.7 Stresses obtained from finite element method using STAAD Pro

for two different heights

226

Table 5.8 The ratio of the load obtained from theory and the actual test or

approximated load (STAAD pro) for each wall height

228

Table 5.9 The load ratio between two different wall heights (Theoretically

and actual or approximated load)

229

xiv

LIST OF FIGURES Page

Figure 2.1 General process of blast furnace slag 48

Figure 2.2 The SEM image for grinding process by A- ball mill, B- Vibro

mill and C- airflow

54

Figure 2.3 Foam concrete wall prototype before and after testing 89

Figure 2.4 A cross sectional area of Lightweight ferrocement sandwich

panel

91

Figure 2.5 The lightweight foam concrete panel with permanent steel

sheet

92

Figure 2.6 The lightweight sandwich panel designed and tested 93

Figure 3.1 Flowchart describing the methodology taken by the study. 98

Figure 3.2 Particle Size Distributions of binding materials 103

Figure 3.3 Scanning Electron Microscopy of (A) OPC at 5000x, (B)

GGBS at 5000x, (C) GBS at 5000x and (D) GBS at 20000x

105

Figure 3.4 Granulated blast furnace slag (GBS) 106

Figure 3.5 Energy Dispersive X-Ray Analyser (EDX) of (A) Mapped sum

spectrum for GGBS, (B) Mapped sum spectrum for GBS, (C)

Mapping elements layout for GGBS, (D) Mapping elements

layout for GBS

108

Figure 3.6 Sand sieving analysis based on BS 882-92 109

Figure 4.1 Correlation between the actual water demand and GBS and

GGBS replacement levels for (A) series I, (B) series II and (c)

series III

124

xv

Figure 4.2 Correlation between mortar density and GBS and GGBS

replacement levels for (A) series I, (B) series II and (C) series

III

125

Figure 4.3 The foam quantity as a function of GBS and GGBS

replacement levels.

127

Figure 4.4 Compressive strength as a function of age for GBS mixes in

(A) series I, (B) sereis II and (C) sereis III

131

Figure 4.5 Compressive strength as a function of age for GGBS mixes in

(A) series I, (B) sereis II and (C) sereis III (B) GGBS mixes

132

Figure 4.6 The compressive strength at 28 day as a function of

replacement level for different filler to binder ratio for (A)

GBS mixes and (B) GGBS mixes

134

Figure 4.7 Flexural strength at 28 days of age as a function of

replacement level for different filler to binder ratio in (A) GBS

mixes and (B) GGBS mixes

138

Figure 4.8 Flexural strength as function of age for GBS mixes in

comparison with control mixes in (A) series I, (B) series II and

(C) series III

139

Figure 4.9 Flexural strength as function of age for GGBS mixes in

comparison with control mixes in (A) series I, (B) series II and

(C) series III

141

Figure 4.10 Flexural strength at 28 days as a function of its corresponding

compressive strength for (A) GBS mixes and (B) GGBS mixes

143

Figure 4.11 Tensile splitting strength at 28 days as function of replacement

level for (A) GBS mixes and (B) GGBS mixes

146

xvi

Figure 4.12 Tensile splitting strength as a function with age for GBS mixes

in (A) series I, (B) series II and (C) series III

147

Figure 4.13 Splitting tensile strength as a function of age for the mixes

with GGBS replacement levels in (A) series I, (B) series II and

(C) series III

148

Figure 4.14 Splitting tensile strength at 28 days as a function of

corresponding compressive strength for (A) GBS mixes and

(B) GGBS mixes

150

Figure 4.15 The oven dry density as function of replacement level at 28

days of age for (A) GBS mixes and (B) GGBS mixes

153

Figure 4.16 Compressive strength as function of oven dry density at 28


156

Figure 4.17 Ultrasonic pulse velocity at 28 days of age as a function

deferent replacement level for (A) GBS mixes and (B) GGBS

mixes

160

Figure 4.18 UPV as function of age for GBS mixes in (A) series I, (B)

series II and (C) series III

161

Figure 4.19 UPV as function of age for GGBS mixes in (A) series I, (B)

series II and (C) series III

162

Figure 4.20 Compressive strength as function of ultrasonic pulse velocity

at 28 days of age for (A) GBS mixes and (B) GGBS mixes

164

Figure 4.21 Ultrasonic pulse velocity as function of oven dry density at 28


166

Figure 4.22 Drying shrinkage as a function of replacements level at 28


169

xvii

Figure 4.23 Drying shrinkage as a function of age for mixes with GBS in

(A) series I, (B) series II and (C) series III

170

Figure 4.24 Drying shrinkage as a function of age for mixes with GGBS in

(A) series I, (B) series II and (C) series III

171

Figure 4.25 Porosity at 28 days of age as function of replacements level for

three series in (A) GBS mixes and (B) GGBS mixes

174

Figure 4.26 The porosity as a function of age for GBS mixes in (A) series

I, (B) series II and (C) series III

175

Figure 4.27 The porosity as a function of age for GGBS mixes in (A) series

I, (B) series II and (C) series III

176

Figure 4.28 Ultrasonic pulse velocity as function of porosity at 28 days of

age for three series in (A) GBS mixes and (B) GGBS mixes

178

Figure 4.29 The compressive strength as a function of porosity at 28 days

of age in three series for (A) GBS mixes and (B) GGBS mixes

179

Figure 4.30 The oven dry density as function of porosity at 28 days of age

for three series in (A) GBS mixes and (B) GGBS mixes

182

Figure 4.31 Water absorption as a function of replacements level at 28


184

Figure 4.32 Water absorption as a function of ages for the mixes with GBS

in (A) series I, (B) series II and (C) series III

185

Figure 4.33 Water absorption as a function of ages for the mixes with

GGBS in (A) series I, (B) series II and (C) series III

187

Figure 4.34 The water absorption as a function of porosity at 90 days of

age for (A) GBS mixes and (B) GGBS mixes

188

xviii

Figure 4.35 Intrinsic permeability as a function of replacements level at 56


191

Figure 4.36 The intrinsic permeability as a function of porosity at 90 days

of age for (A) GBS mixes and (B) GGBS mixes

192

Figure 4.37 Carbonation depth as function of replacements level at 90 days

of age for (A) GBS mixes and (B) GGBS mixes

195

Figure 4.38 The carbonation depth as function of age for GBS mixes in (A)

series I, (B) series II and (C) series III.

196

Figure 4.39 The carbonation depth as function of age for mixes with

GGBS in (A) series I, (B) series II and (C) series III

198

Figure 4.40 The carbonation depth as a function of intrinsic permeability at

90 days of age for GBS mixes

199

Figure 5.1 Cross section of the wall consist of two single (ribbed) panels

(mm)

204

Figure 5.2 Design concept for (A) single ribbed panel and (B) individual

wall consist of two single panel (mm)

205

Figure 5.3 Single panel mould shows the sides middle rib groove 211

Figure 5.4 The dimension and the steps of fabrication of mould of single

panel (mm)

212

Figure 5.5 The steel fabrication in (A) and the jointing method in (B) 213

Figure 5.6 The sequence of casting the panels in (A) prepare the moulds

for casting the optimum mix, (B) casting the outer shell and

ribs, (C) remove the inner polystyrene and (D) casting of inner

panel with insulation density

215

xix

Figure 5.7 A) Nominal restrain end simulation and (B) the position of

LVDT for the wall panel

216

Figure 5.8 Strain gauges position and LVDT in each face of wall A 217

Figure 5.9 Strain gauges position and LVDT in each face of wall B 218

Figure 5.10 Load to horizontal displacement for wall A and B 219

Figure 5.11 Load to vertical displacement for wall A and B 220

Figure 5.12 The cracking pattern in wall A that observed during the test 220

Figure 5.13 Stress-strain curves for wall A at (A) A-1 panel and (B) A-2

panel

221

Figure 5.14 The cracking pattern in wall B that observed during the test 222

Figure 5.15 Stress-strain curves for wall B at (A) B-1 panel and (B) B-2

panel

223

Figure 5.16 The unlevelled load distributor during the testing of wall B 224

Figure 5.17 Maximum stress due to 391KN applied load for wall with

1.8m height

227

Figure 5.18 Maximum stress due to 391KN applied load for wall with

2.8m height

227

xx

LIST OF EQUATIONS Page

Equation 2.1 Kearsly’s target density equation 20

Equation 2.2 Determined target density for foam concrete contained fly

ash as cement of sand replacement

20

Equation 2.3 Oven dry density 21

Equation 2.4 The relation between compressive strength of the foam

concrete and the air content

26

Equation 2.5 Portland cement hydration 56

Equation 2.6 Pozzolanic reaction 56

Equation 2.7 Slag activity index 57

Equation 3.1 Activity index 99

Equation 3.2 Water absorption (weight%) 117

Equation 3.3 Porosity 117

Equation 3.4 Intrinsic air permeability (K) 118

Equation 5.1 Design ultimate axial load for slender braced solid wall 208

Equation 5.2 Design shear stress of the bolt 209

xxi

LIST OF ABBREVIATIONS

GBS Granulated Blast Furnace Slag

GGBS Ground Granulated Blast Furnace Slag

SCM’s Supplementary Cementitious Materials

ASTM American Society for Testing Materials

ACI American Concrete Institute

UPV Ultrasonic Pulse Velocity

BOF Oxygen Furnace Slag

EAF Electrical Arc Furnace Slag

LDF Ladle Furnace Slag

SCC Self Compacting Concrete

ITZ Interfacial Transition Zone

LVDT Linear Variation Differential Transformer

nw Ultimate design load per meter run

xxii

SANGGA RELAU BAGAS BERBUTIR DALAM PANEL STRUKTUR

RINGAN UNTUK PERUMAHAN

ABSTRAK

Sangga relau bagas berbutir (GBS) adalah bahan buangan utama yang

dihasilkan oleh industri besi. Dalam usaha untuk menjadikan sebagai bahan

pozzolanik yang berkesan, GBS perlu dikisar. Dengan proses tersebut, ianya

mengakibatkan penambahan kos dan meletakkan tenaga pengeluaran yang lebih,

dan hasilnya, pelepasan gas yang tinggi kepada alam sekitar. Kajian ini bertujuan

untuk menggunakan GBS sebagai pengganti simen separa untuk pengeluaran konkrit

busa. GBS digunakan sebahagiannya bagi menggantikan simen pada tahap

penggantian 30-70% mengikut berat simen pada ketumpatan 1300 kg /m3 campuran

konkrit berbusa menggunakan tiga nisbah pengisi kepada pengikat yang berbeza

(1.0, 1.5 dan 2.0). Dalam usaha untuk mempunyai pemahaman yang lebih baik

tentang perbezaan prestasi antara GBS dan sangga relau bagas hancur (GGBS) yang

digunakan secara meluas, GGBS telah digunakan dalam menghasilkan konkrit

berbusa menggunakan ketumpatan, tahap penggantian dan nisbah pengisi untuk

pengikat yang sama. Sebanyak 36 campuran disediakan dan telah diuji untuk sifat

fizikal, mekanik dan ketahanan pada tempoh masa yang berbeza. Hasil kajian

menunjukkan campuran optima konkrit berbusa GBS adalah campuran yang

mengandungi 30% daripada GBS dan nisbah pengisi untuk pengikat 1.5. Campuran

ini dipilih untuk fabrikasi kelompang luar untuk panel dinding pratuang. Panel

dinding direka sebagai dinding tanggung beban yang dibuat daripada dua bahagian

lapisan disambungkan bersama-sama menggunakan bolt keluli. Kedua-dua

kelompang luar direka sebagai panel berusuk dan teras dalaman yang terdiri daripada

campuran 500 kg/m3 konkrit berbusa. Melalui ujian eksperimen, panel dinding

xxiii

mencapai purata beban pemecah sebanyak 391kN, iaitu 51.6% lebih tinggi

berbanding dengan beban teori yang diperolehi menggunakan beban rekabentuk

muktamad.

xxiv

GRANULATED BLAST FURNACE SLAG IN STRUCTURAL

LIGHTWEIGHT PANEL FOR HOUSING

ABSTRACT

Granulated blast furnace slag (GBS) is the main waste material produced by

the iron industry. In order to activate as an effective pozzolanic material, GBS needs

to be ground. Hence, adding to its value in cost and putting in to its production more

energy, and as a result, more gas emissions to the environment. This study aimed on

using GBS to be used as partial cement replacement for the production of foam

concrete. GBS is used to partially replace cement at replacement levels of 30-70% by

weight of cement in a 1300kg/m3 foam concrete mix using three different filler to

binder ratios (1.0, 1.5 and 2.0). In order to have a better understanding about the

difference in performance between GBS and the widely used enhanced ground

granulated blast furnace slag (GGBS), GGBS was used in producing foam concrete

using similar density, replacement levels and filler to binder ratios. A total of 36

mixes were prepared and were tested for their physical, mechanical and durability

properties at different ages. Results showed that the optimum foam concrete GBS

mix was the mix that contained 30% of GBS and with filler to binder ratio of 1.5.

This mix was chosen for the fabrication of the outer shell for the precast wall panel.

The load bearing wall panel made out of two halves connected together using steel

bolts. The outer shells are designed as a ribbed panel and an inner core made out of a

500kg/m3 foam concrete mix. Through the experimental test, the wall panels

achieved an average breaking load of 391kN, which is greater by 51.6% in

comparison to the theoretical load determined using the ultimate design load.

1

CHAPTER 1

1.1 INTRODUCTION

Due to its versatility, economy, raw materials availability, durability and

strength; concrete is the most widely used material on the planet after water. It can be

designed to endure the harshest of environmental circumstances and can be

fabricated to take any shape and form (Ozlutas et al., 2012). Although concrete is

used extensively, it is a huge contributor to global warming. In the construction

industry, and especially in the production of concrete, the amount of crushed rocks

and gravel needed annually is estimated to be up to 11 billion tons (Mehta, 2001).

Furthermore, to produce a ton of cement, the needed energy consumption and the

emitted emissions of carbon dioxide (CO2) into the atmosphere are estimated to be

approximately 150 kWT and 0.81 tons, respectively (Chandra, 1996; Huntzinger and

Eatmon, 2009).

It is a well-known fact that technology is becoming increasingly prominent in

the construction industry. This prominence is the result of the construction

industries’ need to produce innovative building materials. Hence, nowadays,

concrete contents are not limited to cement, aggregate, and water, but it also has

minerals and admixtures that can enhance the quality of the concrete and reduce its

negative impact on the environment (Aı̈tcin, 2000). In addition, new types of

concrete have been developed to ensure the creation of more environmentally

friendly concretes. This is done by reducing the concrete’s exploitation of natural

resources and reducing the concrete’s energy consumption by making them lighter

(Ul Haq and Liew, 2007).

2

Scientists and engineers are continuously striving towards the creation of

innovative chemical admixtures and supplementary cementing materials (SCMs).

The use of such materials conserves energy and has environmental benefits because

of reducing the amount of manufactured cement, and as a result, reducing the amount

of green house emissions to the atmosphere. Strict regulations and air pollution

controls caused the production of numerous industrial by-products that can be used

as SCMs. Such examples are fly ash, ground granulated blast furnace slag (GGBS),

metakaoline and rice husk ash. These materials have been typically used in concrete

manufacturing for the sake of cement content reduction, workability and strength

improvement, and durability enhancement (Chandra, 1996; Siddique, 2007; Siddique

and Khan, 2011).

New types of concrete have been developed to counter the effects of global

warming. Concrete types that are lightweight or use lightweight materials are an

attempt to re-establish concrete as an environmental friendly material (Noordin and

Awang, 2005). Lightweight concretes when used in construction reduce the cost and

sizes of the super and substructures in the building. Lightweight building

components also reduce the energy consumption used in their transportation and

placement. In addition, using lightweight concrete in the construction of buildings

will reduce the building’s energy consumption used for cooling and heating (Fouad,

2006).

Foam concrete, as a type of lightweight concrete, has been proven to be more

environmentally friendly as it uses fewer natural resources than conventional

concrete. Additionally, it is superior to conventional concrete in terms of fire

resistance as well as thermal and sound insulation. Foam concrete can offer moderate

mechanical properties, reduce the weight of superstructures or substructures,

3

minimise the overall cost of construction, and it can be handled and constructed

relatively faster and easier (Kearsley, 1999; Mahmood, 2010; Noordin and Awang,

2005).

Aiming on making foam concrete more environmentally friendly and more

cost effective (Huntzinger and Eatmon, 2009), extensive research has been done in

using SCMs in its fabrication. SCMs such as fly ash, GGBS and rice husk ash has

been used as partial or complete replacements for the binding and/or filler materials

(Neville, 1996).

GGBS is a by-product of the iron industry. In a 1500C blast furnace, iron

ore, limestone and coke are heated up and melted. As a result of the melting process,

two products emerge and they are molten iron and molten slag. Due to its lightness,

the molten slag floats on the molten iron. The molten slag comprises of silicates and

alumina from the original iron ore with a combination of some oxides that originate

from the limestone. As mentioned before, GGBS has been used extensively in

concrete as a partial cement replacement at different levels by weight of cement.

GGBS is known to have a positive impact on the strength and durability of concrete

(Siddique, 2007).

1.2 PROBLEM STATEMENT

According to a report published by the World Steel Association in 2013,

Malaysia was placed among the top 25 countries that produce an average 5.9 million

tons of steel annually (World Steel Association, 2010). The processing of each ton of

steel produces around 300 kilograms of by-product materials (Neville, 1996).

Specifically, the steel slag waste in Malaysia is around 1.77 million tons per year.

65% of slag waste is used as GGBS and the remainder, which is around 620,000

tons, is disposed in the environment (Motz and Geiseler, 2001). The storage of slag

4

not only occupies large amounts of land resources but also has a negative impact on

the environment by polluting the soil, underground water and the atmosphere (Li et

al., 2015).

GGBS has been exploited extensively in the production of concrete.

However, after several attempts done by (Bijen, 1996; Chen, 2007; Chi et al., 2012;

Memon et al., 2007; N. Arreshvhina et al., 2006; Parniani et al., 2011; Wang et al.,

2005; Yüksel et al., 2007; Yüksel et al., 2008), the integration of GGBS was mostly

limited to conventional concrete while only a few researchers investigated the

possibility of integrating GGBS in foam concrete. In addition, the replacement level

of the binder was also limited (Pan et al., 2007; Sanjaya et al., 2007; Wee et al.,

2006; Wee et al., 2011).

Granulated blast furnace slag (GBS) is yet to be investigated as a partial

cement replacement. The utilisation of GBS in concrete production will cause a

reduction in both cost and energy consumption. It is a known fact, that slag particles

require longer time to be ground than that of cement clinker; hence, require more

energy (Zandi and Vefa Akpinar, 2012). Conventional methods of construction are

divided into two major components. The first component is the structural system,

which comprises of beams, columns and slab frames that are cast in-situ. The

construction of these frames goes through four operations.

These operations are erecting the timber formwork and scaffolding, erecting

the steel bars for reinforcement, fresh concrete pouring into the form and finally, the

dismantling of formwork and scaffolding. These conventional methods are labor

intensive, tiresome and require a lot of onsite coordination. The second component

consists of erecting the partitions, which consist of brick work and plastering (Abdul

Kadir et al., 2006).

5

As a response to the problems associated with conventional construction

methods, the technology of industrialised construction is becoming a preferable

option, especially in making lightweight prefabricated structures, which perform

better than conventional concrete due to their lesser weight, thermal insulation

properties, and good strength to weight ratio (Sumadi and Memon, 2008). Along

with the benefits of utilising the IBS application that was mentioned by in previous

studies (Onyeizu et al., 2011; Taherkhani et al., 2012), IBS technology saves

approximately 20% of the wastages from the overall construction cost, such wastages

typically occur when using conventional construction methods (Lim, 2006).

The pre-fabrication and pre-casting of structural wall panels have many

advantages than the other systems. A precast structural wall has the capacity to

eliminate the structural frame system (columns and beams), sustain the lateral and

gravity loads, reduce the exterior and interior frame (if they are present in

construction), and increase the span of the slab. Furthermore, it is able to increase the

thermal insulation and become part of the precast wall (Ragan, 2011). Moreover, if

the Malaysian construction industry adopts the IBS construction system, a total

reduction of 4.72 million tons of CO2 emissions can be achieved.

In addition, when selecting a precast wall panel system in a given structure, a

total reduction in emissions of 26.27% is achievable (Omar et al., 2014). However,

wall panels constructed using conventional concrete are heavy and require special

attention when transported and erected into their position. Therefore, lighter weight

wall panels are a good solution in reducing both the cost and energy consumption of

such construction method.

Motivated by the problems mentioned previously in this section, this study

incorporated GBS as a partial cement replacement into producing foam concrete. In

6

addition, a GBS foamed concrete mix is used to fabricate a lightweight wall panel,

which will be designed and used in the construction of a low medium cost house.

1.3 OBJECTIVES OF THE STUDY

The aim of this study is to investigate the possibility of using GBS in the

production of foam concrete. The GBS is used to partially replace cement at different

replacement levels. The assessment of such incorporation is made through the

determination of the physical, mechanical and durability properties of the GBS foam

concrete. For the sake of comparison, foam concrete containing similar cement

replacement levels of GGBS has been prepared and its physical, mechanical and

durability properties were determined. Finally, the foam concrete mix containing

GBS that offers a balance between maximum GBS content and properties is used to

fabricate the lightweight wall panel. Therefore, the following objectives are set to be

achieved by this study:

1- To investigate the physical, mechanical and durability properties of foam

concrete using GBS as cement replacement at different levels and

binder/filler ratio.

2- To compare the properties of GBS and GGBS foam concrete using similar

replacement levels and binder/filler ratio.

3- To establish the optimum replacement level and mix ratio of GBS in foam

concrete based on adequate mechanical, physical and durability properties.

4- To construct a functional precast load-bearing wall for low-rise residential

buildings using the optimum GBS foam concrete mix.

7

1.4 SIGINIFCANCE OF THE STUDY

From an environmental perspective, utilising GBS as partial cement

replacement in foam concrete will reduce the dependency on cement and as a result

decrease the carbon footprint of foam concrete. In addition, GBS utilisation will

reduce the negative impact of leftover slag on the environment. As a result increasing

the possibility of using such a slag in the production of other types of concrete.

Moreover, using GBS instead of GGBS will eliminate the energy consumed for the

production of GGBS. Furthermore, GBS is more cost effective than its ground

counter part, hence, manufacturing a cheaper type of foam concrete.

Since GBS is a new material that its incorporation as a partial cement

replacement is yet to be investigated, the effect of GBS as a partial cement

replacement was compared to the well-known and the extensively researched GGBS.

The uniqueness of such an endeavour was to increase the knowledge about the

difference in performance of these two materials. These two materials (GBS and

GGBS) were used to partially replace up to 70% of the cement in foam concrete

mixes that have a semi-structural density of 1300kg/m3.

The foam concrete mix that incorporates a maximum amount of GBS without

affecting the properties negatively was used to fabricate the precast wall panel. The

panel has unique features in itself. The optimum GBS foam concrete mix will be

used to fabricate the outer shell in which it is using a semi-structural density and not

a structural density. In addition, the wall panel will be made out purely from foam

concrete, hence, creating a lightweight wall panel used for structural applications. In

addition, the uniqueness of this wall panel also arises from its thinner outer shell

(thickness = 30mm), which is designed as a ribbed panel.

8

1.5 SCOPE OF THE STUDY

In this study, GBS will be used as a partial cement replacement in foam

concrete having a semi structural density of 1300kg/m3. GBS will replace the cement

using a replacement level of 30-70% by weight of cement at 10% increments. Also

three different filler to binder ratios will be utilised namely 1.0, 1.5, and 2.0. Each

GBS foam concrete mix is tested for its mechanical (compressive strength, flexural

strength, and splitting tensile stress), physical (density, drying shrinkage, ultrasonic

pules velocity, and porosity) and durability properties (intrinsic permeability, water

absorption, and carbonation) at various ages.

At the same time and for the sake of comparison, foam concrete mixes

containing GGBS with similar replacement levels, density and filler to binder ratio

are prepared and tested for similar properties at the same age. The lightweight load-

bearing wall will be casted using the optimum GBS foam concrete mix. The wall

panel design is based on a two story low medium cost house, which its details are

listed in chapter five. For the sake of easiness of handling and transportation, the

lightweight wall is made out of two halves. Each half panel is designed to have an

outer shell and core. The outer shell is designed as a ribbed panel and is fabricated

from the optimum GBS foam concrete mix. While, the core is made out of lower

foam concrete density (100% cement). The two halves are joined using steel bolts to

form the lightweight load-bearing wall.

1.6 THESIS LAYOUT

This thesis comprises of six chapters. Chapter One already discussed the

motive of this thesis and its aims, significances and scope. Chapter Two will review

the literature related to this study. This chapter contains mainly three parts, the first

part discusses the applications of foam concrete, foam concrete properties for fresh

9

and hardening density, foam concrete constituents, and the effect of the type of by-

product material or pozzolanic material used as a filler or binder on the properties of

the mix. The second part of this chapter will briefly discuss the by-product material

and, especially, steel slag and it’s processing. It also discusses the effects of GGBS

as a by-product material on properties of concreting material (normal, mortar, and

lightweight concrete) in the fresh and plastic phases. The third will review types of

concrete wall panels; the standards used to design these wall panels and studied foam

concrete wall panels.

Chapter Three explains in detail the experimental sequence and the methods

that will achieve the objectives of this study. This chapter consists of two parts; the

first part describes the preliminary study examining GBS as a supplementary

cementitious material. Furthermore, it examined the use of GBS as a foam concrete

constituent. The second part is the main study, which describes the foam concrete’s

constituents, properties, material testing, and mixing procedure. The properties of

fresh and hardened foam concrete have been tested according to the standards.

Moreover, the machinery and testing procedure for the wall was also included as part

of this chapter.

Chapter Four reviews the results of the created foam concrete’s mechanical,

physical, and durability properties. The results are illustrated in graphs and tables,

which discuss the effects of GBS and GGBS on fresh and hardened properties of the

foam concrete. Meanwhile, Chapter Five will discuss the design concept of the wall

panel. This chapter will explain the wall’s design concept and its mathematical

calculations. The testing procedures and the results obtained from the actual

laboratory test and the engineering software (STAAD Pro) will be discussed.

10

Chapter Six will list the conclusions drawn from this research and laid down

a number of future works based on the current study.

11

CHAPTER 2

LITERATURE REVIEW AND RELATED WORK

2.1 INTRODUCTION

This chapter describes various topics that are related to the objectives of this

research project. It initially describes foam concrete discretion, application,

constituents, and its fresh and hardened characteristics. Also, various cementaious

materials that have been used as binder or filler as well as their effect on the

properties of foam concrete will be illustrated in this chapter. Furthermore, this

chapter will review the types of produced by-products as well as their properties and

utilisation into the construction industry. Moreover, this chapter will review and

discuss the precast wall panels using lightweight concrete as well as their advantages

and disadvantages in comparison to other systems.

2.2 FOAM CONCRETE

Hoff (1972) defined foam concrete as a type of lightweight concrete with a

homogenous cell or void structure attained by the inclusion of a foaming agent or by

the generation of gas within a fresh cementation mixture. It has been calculated that,

possibly, between 30-80% of the total volume of foam concrete is made up of air

bubbles or foam. In addition, Tam et al. (1987) described it as slurry or mortar with

air bubbles, ranging in size from 0.1 mm to 1 mm, that have been introduced

chemically or mechanically into the wet mixture. Fouad (2006) described foam

concrete as a low-density material with structural cells or homogeneous voids

generated by the introduction of preformed foam or gas into the mortar matrix. The

common casting densities range from 320 to 1920 kg/m3.

12

Therefore, based on the definitions above, foam concrete can be defined as a

lightweight concrete that has different densities ranging from 320 to1920 kg/m3. The

constituents of foam concrete can be any mortar mixture with or without an infill

material. Any type of binder, like normal concrete, can be used, and instead of coarse

aggregate, air bubbles with diameters ranging from 0.1 to 1 mm can be introduced

into the matrix mechanically or chemically by introducing gas in the wet mixture.

This foam does not perform any chemical action until the cement sets and holds the

desired shape. The amount of air or foam that is added to the mortar slurry has been

calculated to range from 30% to 80% of the total volume (ASTM, 2004c; Barnes,

2008; Fouad, 2006; Hoff, 1972; Liew, 2005; Tam et al., 1987).

There are two types of foam concrete based on the curing conditions, namely,

autoclaved and moist foam concrete. In the first type, the foam concrete is cured

under high-pressure steam at temperatures ranging from 180 to 210 oC, while in the

second type; the foam concrete is cured under atmospheric pressure and steam. The

first method of curing is generally used for making precast structural cellular

elements. Precast moist-cured products are used as secondary structural elements

because of their good thermal and sound insulation properties (Al-Noury et al., 1990;

Tam et al., 1987).

Liew (2005) classified foam concrete based on the densities utilised in

construction, while Fouad (2006) listed the constituents of the foam concrete based

on density. Table 2.1 illustrates Liew’s classification. It is worth mentioning that the

production of aerated concrete was commercialised in Sweden in 1929 and was

rapidly distributed to other parts of the world at the end of the Second World War.

From that time, various methods have been devised and different types of foam

concrete have been produced and used in construction applications in many countries

13

(Abdullah et al., 2006; Brady et al., 2001).

Table 2.1: Utilization of foam concrete in various application (Liew, 2005)

Based on density Author Density range (kg/m3) Application

Liew (2005)

300-600

Thermal insulation for flat roofing with required grading. Floor sub-surfaces. Block infills for sub-floor slabs. Cavity walls filling. General thermal and acoustic insulation. Heat insulation slabs.

600-800

Internal partition wall blocks and panels. Roofing slabs. Floors. Sub-surface for stables, pig sties and poultry farms. Walls, floor sub-surfaces of large cool rooms. Façade panels. Trench reinstatements.

600-800

Internal partition wall blocks and panels. Roofing slabs. Floors. Sub-surfaces for stables, pig sties and poultry farms. Walls, floor sub-surfaces of large cool rooms. Façade panels. Trench reinstatements.

900-1200

External wall blocks and panels, both structural and non-structural. General sound-proofing in industrial areas.

1200 -1800

Medium weight blocks and slabs. Large reinforcement slabs and panels. Walls, either precast or poured in situ. Garden ornaments

2.3 MATERIALS UTILISED IN FOAM CONCRETE

As mentioned before, foam concrete can be based on slurry or mortar mixture

that consists of Portland cement and water or Portland cement, fine aggregate (sand),

and water. The binder can be Portland cement or blended cement, consisting of

Portland cement slag, Pozzolans, lime with siliceous material, fly ash, metakaolin, or

any other hydraulic material (ACI, 1996; Brady et al., 2001). Pozzolanic materials

are utilised with varying percentages to replace cement or sand in the foam concrete

mixture. These materials are cost efficient and environmentally friendly, as well as

14

they can enhance the properties of the foam concrete in its fresh and plastic phases

(ACI, 2006). It is possible to use admixtures (chemical additives) in foam concrete as

a percentage of the total weight of the binder.

The tests listed in ASTM C796 (2004d) and the 1996 and 2006 ACI reports

are recommended for the trial mixes before the admixtures and supplementary

materials are utilised in the production of foam concrete in order to determine their

compatibility with the foam concrete. The typical foaming agents are protein

hydrozylates or synthetic surfactants with a density varying between 32 to 64 kg/m3,

as recommended by ASTM (ASTM, 2004c). However, ACI (2006) and Fouad

(2006), proposed a density of 40 to 65 kg/m3 and 32 to 56 kg/m3, respectively.

Kearsley (2006) determined the compatibility of the foaming agent by mixing

samples containing only cement, water, and foam. The water required was obtained

from various foam percentages and was based on visual observations. Essentially,

there are two methods for the use of preformed foam in the production of foam

concrete, namely the wet and dry method. The first method, which is suitable for the

production of foam concrete with a density of up to 1000 kg/m3, involves spraying a

solution of the foaming agent with water through a fine mesh to generate bubbles

with a diameter of 2 to 5 mm.

The second method is the dry preform method, which involves using the

power of an air compressor to force the foaming agent and water into a mixing

chamber, thus resulting in the generation of stable air bubbles having a diameter of

less than 1 mm (Barnes, 2008; Brady et al., 2001; Ramamurthy et al., 2009). The

preformed foam technique is the more economical method of producing foam

concrete as it uses less foaming agent and the mix can be controlled and possibly

adjusted if there is a human error (Ramamurthy et al., 2009; Wee et al., 2006).

15

Due to the small size of bubbles, the near bubble skeleton, and the stability of

the protein foaming agent reflect the bond strength of the final foam concrete product

(Mcgovern, 2000; Nambiar and Ramamurthy, 2007a; Othuman Mydin, 2010).

Dransfield (2000) stated that although a synthetic foaming agent can be easily

formulated and it is more stable, its high expansion can open cells and create large

bubble sizes which can reduce the strength of the foam concrete. Therefore, a protein

foaming agent is preferable to a synthetic one. A filler or fine aggregate, with a

maximum particle size of not more than 5 mm, can be used.

Furthermore, a high strength foam concrete can be obtained by mixing 60 to

95% sand passing through a 600-micron sieve (ACI, 1996; ACI, 2006; ASTM,

2004a; ASTM, 2004c; Barnes, 2008; Brady et al., 2001; Fouad, 2006; Ramamurthy

et al., 2009). Table 2.2 reviews several researches that had been carried out utilising

different materials and admixtures in powder or liquid form in foam concrete.

(Fouad, 2006; Hoff, 1972; Liew, 2005; Tam et al., 1987) (ACI, 2006; ASTM, 2004c), (ACI, 1996) (Dransfield, 2000; Kearsley, 2006) (BSI, 1985b) (BSI, 1992b),

16

Table 2.2: Utilization of various materials as additives and admixtures in constituents of foam concrete

Author Density Kg/m3

Mix ratio

Replacements (%)

Additives (%) W/b Foam

type Foam

density (Ranjani and Ramamurthy, 2012)

1000-1500 1:1 FAa (10-30)

(OPC - - Synthetic 25-38

(Jitchaiyaphum et al., 2011) 800 - FAa (10-30)

(OPC) - 0.5 Protein 45

(Wee et al., 2006) 600-1900 - GGBS (50)

(OPC) - 0.3 Protein -

(Kearsley and Wainwright, 2001b)

1000-1500 -

FA & PFb (50-67.7-75)

(OPC) - 0.3 Protein 70

(Tam et al., 1987)

1300-1600

1:1.58-1:1.75 - - 0.6-

0.8 Protein 59

(Jones et al., 2003) 1000 1:1.83

FA (30) (OPC),

FA coarse (30) (sand)

- 0.5-1.11

- 50

(Jones and McCarthy, 2005b)

1400-1800

1:1.5-1:2.3

FA (30-50) (OPC), FA coarse (50-100)

Spd 0.26-0.5

Synthetic 50

(Jones and McCarthy, 2005b)

1000-1400 1:1.83

FA coarse (66-70) (sand)

- 0.5 Synthetic 50

(Nambiar and Ramamurthy, 2006)

1000-1500 1:1 FA (50-100)

(sand) - - Protein 50

(Pan et al., 2007) 620-1600 1:2.3 - - 0.7 Protein -

(Nambiar and Ramamurthy, 2007b)

840-1753

1:2

FA (0-100) (sand)

-

0.94-1.65

Protein

40

(Wee et al., 2011) 693-1635 1:0 GGBS (50)

(OPC) Sp (8ml/kg) 0.22-0.6 Protein -

(Zulkarnain and Ramli, 2011) 1150 1:1.5 SFc (10-15)

(OPC) Sp 0.45 Protein 80

(Chindaprasirt and Rattanasak, 2011)

1600 1:2.5 FA (15-30) (OPC)

Propylene glycol (1)

Triethylene glycol (1)

Dipropylene glycol(1)

0.5 - 50

(Shi et al., 2012) 500-1000 1:0,

1:0.6

FA (20-40-60)

(OPC) Sp (0.1) 0.3 Protein 55

(Mydin, 2011) 1000 1:0.5 - 0.5 0.5 Protein 80

(Panesar, 2013) 500-900 - - - 0.29 Protein &

two Synthetic

65 45-65, 50-60

(Lim et al., 2013)

1300

-

OPA (10-20) (sand)

-

0.52-0.6

Synthetic

45

(Awang et al., 2014) 1300 1:2 OPA (25-65)

(OPC) Sp (1) 0.45 Protein 65

(Rahyan et al., 2008)

1000-1500 1:1.5 - Sp (1.25) 0.45 Protein 80

aFA: Fly ash, bPF: Pozz-Fill, SFc: Silica fume, Spd: Super-plasticiser

17

2.4 PROPERTIES OF FOAM CONCRETE

This section will explain various properties of foam concrete in fresh and hardened

stages.

2.4.1 CONSISTENCY AND STABILITY OF FOAM CONCRETE

The workability of foam concrete, whether it is mortar-based (cement, sand

and water) or neat cement, is described by the ACI (2005b) as the characteristic of a

normal fresh mortar mix that is homogeneous and permits easy mixing, placing,

compacting, and finishing. A common workability test for a basic foam concrete

mixture is the Brewer test or any other test in ASTM C230 (ASTM, 2004b). In a

study conducted by Li (2013), the workability of the mortar was determined based on

the modified cylinder plate method in accordance with ASTM C230 (ASTM,

2004b), which was adopted from the company that supplied the foaming agent and

foam generator.

Valore (1954) noticed that at lower foam concrete densities, the water to

cement ratio increased with the increase of sand level in the mix. Moreover, he stated

that the amount of water required in the mix was determined by the consistency

rather than by a predetermined water/cement ratio. Based on the actual flow table

test, Kearsley and Mostert (2005) were able to determine the workability of a base

mixture of foam concrete according to ASTM C230 (ASTM, 2004b). The water

required for the cement used in their study made up 35% of the total weight of the

cement, which meant that the minimum water to cement ratio needed to avoid the

cement pulling the water from the foam is 0.35. When fly ash was included in the

matrix, the water demand was 0.25 litres for each kg of fly ash. This phenomenon

occurred due to the spherical shape of the particles. This is also reported in a study

carried out by Pretorius (2006). An additional reason for this phenomenon is that fly

18

ash (pozzolanic material) is not engaged in the hydration process during the early

stages (early hours) because it only participates in the processes after the formation

of calcium hydroxide. (Pretorius, 2006)

Fly ash, which contains up to 10% unburnt carbon, has a large particle size

(more than 45 micron) and is reported to increase the water required to achieve a

specific workability (Kearsley, 1999). However, when fly ash is excluded, Kersealy

(2006) indicated that the optimum w/c ratio is in the range of 0.38 based on the foam

content. However, this ratio increased with increment of the ash ratio. Furthermore,

water demand tends to increase with the increasing percentage of foam. The

inclusion of GGBS in the foam concrete base mixture at an equal percentage of the

binder can increase workability. However, increasing the level of GGBS content in

the mixture in addition to the low w/c ratio can cause the foam to separate from the

paste (Brady et al., 2001).

Lim et al. (2013) defined the consistency of foam concrete as the freshly

obtained density over the designed density. On the other hand, Ramamurthy et al.

(2009) described it as the ratio of water to solid that can attain the design density. If

the base mixture of the foam concrete has a low consistency, it will cause the bubbles

to brake due to the stiffness of the mixture, and if it is too watery, it will lead to an

increase in density due to segregation. Furthermore, the consistency of the foam

concrete tends to decline with the addition of foam into the base matrix. In other

words, the consistency of the foam concrete depends on the volume of water added

for the desired density, the type of filler, and the water to solid ratio (Brady et al.,

2001; Ramamurthy et al., 2009). Nevertheless, Jones and McCarthy (2005c)

concluded based on their experiment that replacing the unprocessed fly ash with sand

enhances the consistency of the matrix compared to using sand as the filler because

19

of the finer state and shape of the fly ash particles. Meanwhile, Lim et al. (2013)

concluded that the incorporation of oil palm ash as a filler replacement decreases the

flow-ability of the fresh mix.

The stability of foam concrete is related to the consistency of the base mix

and can be represented by the ratio of water to solid, which differs according to the

filler type. Lim et al. (2013), Valore (1954), and Nambair and Ramamurthy (2007b)

described the stability of foam concrete as the ratio of the demoulded (hardened)

density over the obtained density (fresh). In general, the consistency and stability of

the foam concrete are affected by the amount of foam, the w/s ratio, and the other

solid materials that are introduced into the mixture (Brady et al., 2001; Ramamurthy

et al., 2009). Jones and McCarthy (2005c) and in other paper that published by the

main authors above at (2006) suggested that the stability of foam concrete can be

indicated by comparing the theoretical and actual amount of foam that is added to

achieve the desired plastic density which is within the range of ±50 kg/m3 of the

design value or 3% of the fresh (wet) density.

Also, it was indicated that in terms of the stability of foam concrete with

unprocessed fly ash as a replacement for the sand, the amount of foam required is

more than three times that of normal filler. This is due to the high consistency of the

base mixture as well as the high content of carbon in the ash. Panesar (2013)

mentioned in his study that the inclusion of fine aggregate in the base mixture of the

foam concrete increases the stability of the foam concrete compared to a slurry (neat

cement) mixture, which, although it has more consistency, it is unable to hold the air

bubbles due to segregation.

20

2.4.2 DENSITY

In order to determine the oven dry density, the ASTM C513 (2004e) and BS

EN 12390 part seven at (2009a) recommended that a temperature of 110 oC ± 5 oC

should be applied to the specimen for 24 hours, and the dimensions of the sample

and its weight per cubic meter or cubic foot should be determined. Both dry and

fresh densities of foam concrete are important to determine the requirements of the

mix design, to ensure quality control, and because most of the characteristics of foam

concrete are explained with regard to oven dry density (Fouad, 2006; Jones and

McCarthy, 2006; Ramamurthy et al., 2009).

Basically, preformed foamed concrete with a cement to sand based mixture

has a higher density and requires more cement (Ramamurthy et al., 2009) than fly

ash, which has a relatively lower density and requires less foam, as the filler

replacement. Furthermore, A1-Noury et al. (1990) mentioned that the loss in dry

density of foam concrete increases with the increasing water to cement ratio. Due to

the loss of water in the plastic density of foam concrete, Kearsley and Mostert (2005)

determined that the difference added to the dry density (oven-dried) of the foam

concrete should range from 600 to 1200 kg/m3 in order to obtain the target density,

as calculated from the liner equation below:

Target density = 1.034 Pdry+ 101.96 ….2.1

On the other hand, Jones and McCarthy (2005b) used the equations below to

determine the plastic density of foam concrete incorporated with fly ash as a binder

and filler substitute,

D = ! + ! + !, where ! = !" + !"finer, f= FAcoarse+ sand……..… 2.2

Where D is the target plastic density, C is the cement content, f is the content of fine

aggregate, and W is the free water content, which determined as:

21

W= (w/c) × (PC+ !"finer+ FAcoarse)

Nevertheless, Fouad (2006) and Neville (1996), in their calculation of the

amount of solid material based on the oven dry density and with a water content of

20% of the total binder cement weight, made the following assumption:

D = 1.2C × A (C and A in kg/m3)……………..… 2.3

Where D is the dry density, C is the weight of the cement, and A is the weight of the

aggregate.

McCormick (1967) determined the wet density with a difference of 5% from

the design density by using the solid volume calculation method. In his study, he also

examined the effect of the fineness of the sand, the type of foam agent, and the sand-

cement ratio on the wet density of foam concrete. Jones and McCarthy (2005b)

mentioned that the proportion of the foam concrete mix can be designed according to

the plastic density. Nonetheless, it is difficult to do this with the dry density as the

density of the foam concrete usually drops by about 50 to 200 kg/m3, according to

the total water content in the mixture. Thus, the design of foam concrete mix depends

on the foam concrete plastic density and the curing regime.

In a research by Noordin and Awang (2005), it was noted that there was a

reduction of 60-120 kg/m3 in the dry density (oven-dried) compared to the target

density. Thus, indicating that the designed density tends to be higher than the dry

density. The difference in the dry density and the targeted design density is mostly

due to the water-cement ratio and the casting density.

Jeong and Kim (2011) mentioned in his study that the variation between the

wet density and the oven-dry density depends on the amount of cement paste in the

matrix. The difference, however, increases with an increase in the amount of cement

paste. Also, they discovered in their study that the type of the synthetic foaming

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agent also influences the gap between the wet and the oven-dry density. The air-dry

density or air curing method for foam concrete is the most convenient industrial

method. The air-dry density technique relies on many factors, such as weather

conditions (temperature and humidity), duration of exposure to the weather, the

density obtained, and the water to binder ratio. Based on the variables and the casting

conditions, air-dry densities are probably lower by about 80 kg/m3 than the cast

density (Fouad, 2006; Neville, 1996).

2.4.3 COMPRESSIVE STRENGTH

Many factors influence the compressive strength of foam concrete, including

density, quantity of cement in the matrix, w/c ratio, mix proportions, type of binder

and filler, admixture, period and type of curing regime, specimen shape and size, and

pore formation method (Fouad, 2006; Narayanan and Ramamurthy, 2000b). In

addition, the size, spacing, and regularity of the air voids as well as the void to paste

ratio might also affect the mechanical properties of the foam concrete (Wee et al.,

2006).

The curing regime is one of the most important factors influencing the

mechanical properties of foam concrete. The conventional water curing practice

promises a higher strength. It has been proven that relative humidity influences the

compressive strength of the foam concrete when it is exposed to the environment and

its strength could be reduced by about 35% within a humidity range of 30 to 80%

(Lee et al., 2011).

Based on laboratory experiments, Kearsley (2006) concluded that the best

curing for foam concrete is moist curing, also known as curing under plastic cover.

In addition, this method of curing can reduce the cost of foam concrete production. It

has been reported that moist-cured foam concrete is affordable and can be used for

23

many applications (Tam et al., 1987). Moreover, it has been proven that a good

curing regime can generate high compressive strength in the long run regardless of

whether a high level classified or non-classified fly ash is replaced by cement in the

foam concrete (Kearsley and Wainwright, 2001b). On the other hand, the

experimental study conducted by Alwi et al. (2010) indicated that curing in salt-

water results in a higher compressive strength than curing in fresh water and in air

due to the development of a strong matrix bond in the foam concrete samples.

A comparison that was made based on the ash/cement ratio for the mix with

and without foam indicated that increasing the ratio decreased the strength of the mix

without foam, while the mix with the foam acted oppositely or maintained its

strength as the control mix. The optimum replacement level of the ash by cement is

50% for a mix content that has 30 or 40% foam (air voids) (Kearsley, 2006). Better

mechanical properties can lead to optimal strength-to-weight ratio, and this is

achieved by having a dense microstructure with relatively small air voids and large

spacing factor (Wee et al., 2006). (Alwi et al., 2010)

Increasing the w/c ratio in foam concrete positively influences the mechanical

properties as long as there is no reduction in the a/c ratio. The compressive strength

of foam concrete depends on both the water to cement and the air to cement ratios,

unlike mortar, which undergoes a reduction in compressive strength with the increase

in the w/c ratio (Fouad, 2006; Tam et al., 1987; Wimpenny, 2006). Moreover, the

presence of 5% to 2% voids in normal concrete dramatically reduces the strength by

30% to 10%, respectively (Al-Noury et al., 1990). The study by Wimpenny (2006)

indicated a dramatic change in compressive strength for foam concrete that has a

density of 1350 kg/m3. However, he found that the strength remained statically the

same when the w/c ratio was above 0.9 and below 0.75.

24

It was reported that small changes in the w/c ratio due to the amount of water

content in the sand, which varied between 6%-14%, did not have an effect on the

strength of the foam concrete (Tam et al., 1987). The sand to cement ratio affects the

strength and the linear trend reduction when there is an increase in the amount of

sand. Furthermore, it is worth mentioning that the reduction in compressive strength

is not affected by further increases in the sand content. The optimum sand/cement

ratios vary between 0.5-1 for foam concrete containing 20% to 60% foam (Kearsley,

2006). The fineness of the sand has been reported to increase the compressive

strength of the foam concrete (Wimpenny, 2006). This phenomenon is attributed to

the uniform coating on each bubble that prevents overlapping and merging, unlike

coarse sand which forms large and irregular pores and also leads to the clustering of

the bubbles (Jitchaiyaphum et al., 2011; Jones and Giannakou, 2004; Nambiar and

Ramamurthy, 2006).

Wimpenny (2006) utilised an equal amount of w/c and a/c to examine the

effect of integrating GGBS in foam concrete. The researcher found that when cement

is replaced by an equal amount of GGBS, the strength of the foam concrete at 7 days

is reported to be much lower than the mix that has no GGBS. However, the scenario

changes at 28 days as the mix with GGBS develops strength that is higher than the

control mix. It has also been reported that the use of coarse fly ash as a filler in the

base mix of foam concrete enhances the compressive strength of the foam concrete.

This phenomenon can be explained as being part of a pozzolanic reaction, where fly

ash, having a lower specific density than fine aggregate, results in reducing the

amount of foam required (Nambiar and Ramamurthy, 2006; Valore Jr, 1954).

Kearsley and Wainwright (2001a) demonstrated that no harmful or major

effects on the compressive strength of high-density foam concrete for long term

granulated blast furnace slag in structural lightweight panel for...

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