DURABILITY PROPERTIES OF
STABILIZED EARTH BLOCKS
YASER KHALED ABDULRAHMAN
AL-SAKKAF
UNIVERSITI SAINS MALAYSIA
2009
DURABILITY PROPERTIES OF STABILIZED EARTH BLOCKS
by
YASER KHALED ABDULRAHMAN AL-SAKKAF
Thesis submitted in fulfillment of the requirements
for the degree of
Doctor of Philosophy
January 2009
DEDICATION
This thesis is especially dedicated to the following
For their love, support and patience:
- My father, and mother,
- My brother and sisters,
- My wife, and my children,
And all my brothers every were including my home country of Yemen and my
second home in Malaysia
Acknowledgements
All praise be unto Allah and may his peace and blessings be upon his final prophet and
messenger Muhammad peace be upon him.
First and the foremost, I would like to extend my most profound gratitude and
deepest thanks to my principle supervisor Professor Ir. Dr. Mahyuddin Ramli, Universiti
Sains Malaysia, for his guidance, commitment and encouragement throughout the entire
period of the research project . His dedication and continuous guidance enabled me to
remain focused on the research investigation from the beginning of the project to the very
end for all the time spent on coordinating and supervising the whole thesis. Without his
constant support and timely interventions, without Allah and then him, none of this would
have been possible. I would also like to convey my sincere thanks to Dr. Mohd Rodzi Bin
Ismail as the co-supervisor for the project.
My deepest thanks are also due to my parents (father and mother), who have been an
inspiration and I ask Allah to grant them His paradise. Thanks also goes to my family and
my brother and sisters for all the hours of transcribing, proof reading, and patience given to
me in my quest and their great support in highly appreciated.
My sincere thanks are also to the academic and technical staffs at the Universiti Sains
Malaysia and to my University in Yemen (Hadhramout University/ Mukalla) and their staffs
for the assistance rendered.
I would certainly like to thank to the laboratory assistants namely; Mr. Khalid Ahmad, Mr.
Ooi Cheow Lam and Mr. Idris Shaari for their continuous assistance in conducting
laboratory tests for the main experimental investigations. I remain deeply indebted to all and
to those who assisted me during the course of my study and I am asking Allah to guide them
to the right way for the great religion of Islam.
ii
TABLES OF CONTENTS
……………………………………………………………...
ii
Table of Contents ……………………………………………………………….
iii
Acknowledgement
List of Tables ………………………………………………………………….... xi
List of Figures ………………………………………………………………….. xiv
Abstrak ……………………………………………………………..…………… xxi
Abstract ………………………………………………………………….……... xxiii
1
CHAPTER 1- INTRODUCTION
1.1 Introduction
…………………………………………………...…………..
1
1.2 Background
……………………………………..…………………….......
1
………………..………………….....
1
…………………………..………………………...........
7
1.2.1
Why use earth for building?
1.2.2
Low cost
1.2.3
Adobe blocks …………………….…..…………………………… 10
1.2.3.1
Traditional adobe
……………………..…………........... 10
1.2.3.2 Traditional Yemeni clay buildings ………………........... 11
1.2.4
New techniques
…..……………...………………………………. 12
1.2.4.1 Stabilized soil
…………………………………………. 13
1.2.4.2 Compressed earth blocks ……………………………… 14
1.2.5
Water ……………………...……………..………………………… 15
1.2.6
Critical summary
.……...……………..………………………… 16
1.3. Scope of the study .….……………………………..……………………… 17
1.4
Problems statement …………………………………...…………………... 18
1.5 Research objectives
1.6 Hypothesis
…………………………………..………………...... 19
………………………..……………………………………… 20
iii
1.7 Layout of thesis …………………..………………………………………. 21
23
CHAPTER 2- LITERATURE REVIEW
2.1
Introduction ………………………...……………………………………. 23
2.1.1 History of earth materials and traditional clay buildings ……….... 25
2.2
2.3
2.1.2
Previous developments …………………………….…..………... 27
2.1.3
Modern earth building ………………………..…………………. 28
Soil and classification ……………………………..……………………..
31
2.2.1
Mineral compositions of soil ……………..……………………... 31
2.2.2
Soil classification …………………………..……………………. 32
2.2.3
British soil classification system …………..…………………..... 32
2.2.4
Types of soil .………………………………..………………….... 34
2.2.4
Laterite soils ………………………………..……………………. 35
Characteristics of soils …………………..………………………..……… 37
2.3.1
Chemical properties ……………..……………………………….. 37
2.3.2
Physical index properties (basic characteristics of soil) ……….… 38
2.3.2.1
Color …………………………...……………...……...... 38
2.3.2.2 Particle size or texture …………..……………...……… 39
2.3.2.3
Porosity or voids ratio ……………………...………...… 40
2.3.2.4
Specific bulk density …………………………..……..... 41
2.3.2.5
Specific gravity ……………………......……………...... 42
2.3.2.6 Volume-weight properties …………...……………….... 42
2.3.3 Dry density …………….………………………..……………….. 43
2.4
2.3.4
Relationships between basic properties …………..…………….... 44
2.3.5
Property index (plasticity) …………………..………………….... 45
Soil compaction ……………………………..…………………………… 47
iv
2.5
Stabilization ………………………..…………………………………….. 50
2.5.1
Factors affecting the stabilizer properties ……..………………..... 51
2.5.2
Characteristics of stabilization ………………………..…………. 52
2.5.3
Cost saving ……………………………………………..…………. 52
2.5.4 Durability ……………………………………………..………….. 53
2.5.4.1 Moisture resistance and maintenance …………………... 54
2.5.4.2 Critical moisture action ……………………………..…. 55
2.5.4.3 Durability in compressed earth blocks …………..…….. 56
2.5.5
Permeability ……………………………………………..……….. 56
2.5.6 Capillary ……………………………………………..................... 57
2.5.7 Shrinkage …………………………………………….................... 58
2.5.8
2.6
Compressive strength …………………………………..………... 59
Stabilizers ……………………………………………………..…………. 60
2.6.1 Cement stabilization .........……………………………...……….... 61
2.6.1.1 Mechanisms of cement stabilization ……..……..…........ 62
2.6.1.2 Properties of cement-soil ……………………………….. 62
2.6.1.3 Influence on compressive strength ……..…………..….. 63
2.6.1.4 Effect of cement on water absorption … ……………… 63
2.6.1.5 Preparing soil cement mixture
2.6.2
Lime stabilization
……………….……..…. 64
……………………………...……….……….. 65
2.6.2.1 Dosage and preparation ………………..……….………. 66
2.6.2.2 Mechanisms of lime stabilization …………….…..…….. 66
2.6.2.3 Safety ………………………………..……...................... 67
2.6.3
Bitumen stabilization ………………...……………….………..... 68
2.6.4
Preparing emulation ………………..……………………...……... 69
v
2.7
Block compaction ……………………..………………….…………….... 71
2.7.1
Soil stabilized blocks ………………………..………………..….. 71
2.7.2
Standards for block production ………………….....…………..... 73
2.7.3 Stabilizer dosage ………………………………..…..…………..... 73
2.7.4 Mixing process ………………………………..……..…………... 74
2.7.4.1 Optimum water content …………………...………….. 74
2.7.4.2 Batching …..………………………………..………….. 74
2.7.4.3 Curing ……………..……………………….………….. 75
2.8
2.9
Properties of soil for block production ………………………..…………. 76
2.8.1
Characteristics for making blocks ……………..……………….. 77
2.8.2
Raw material tests …………………………..………………….
2.8.3
Sieve analysis example ……………………...……….................. 80
79
Earth and wall techniques ……………………..…………………………. 81
2.9.1
Rammed earth ………………………..…………………………. 84
2.9.2
Mud bricks …………………………..…………………………
2.9.3
Compressed earth block …………………………...…………… 86
2.9.4
Compressed earth block machines …….……………………….. 88
85
2.9.4.1 Sizes of blocks ……………………..……...…............... 88
2.9.4.2 Types of presses ………….…………………………… 89
2.10 Development of mud block in Yemen …………………...……………..... 93
2.10.1 Wadi Hadhramout region ……………………….……………… 93
2.10.2 Shibam Hadhramout …………………….……...............
94
2.10.3 Construction and techniques in Hadhramout region …….……... 95
2.10.3.1 Building materials …………………….................…... 96
2.10.3.2 Construction procedures …………………..................... 98
vi
2.10.4 Mud block technology …………………..…………..……….... 99
2.10.5
New techniques in clay block manufacturing …….……...…… 101
2.10.6 Compressed earth blocks in Hadhramout …………….........…... 102
2.11 Conclusion
………………………………………………………………. 103
CHAPTER 3- EXPERIMENTAL PROGRAMMES
.................…………………………………………............... 106
3.1
Introduction
3.2
Scope of research
3.3
Instruments of the experiments
3.4 Input variables
3.5
…………………………………………….................... 107
…………………………...…………………………........ 108
Materials and methods
3.5.1
……………………..…………………… 107
…………………………………………...…….... 109
Laterite soil .…………………………..………………………... 109
3.5.2 Method of test ………………………..…………………………. 109
3.5.3 Sieve analysis …………….…………..………………............... 110
3.5.4
Characteristics of the cohesive soil (soil properties) ….................. 113
3.5.4.1 Optimum moisture content and bulk density …………. 114
3.5.4.2 Grain specific gravity (Gs) …………………………... 114
3.5.4.3
Organic content
……………………………………… 115
3.5.4.4
Linear shrinkage
…………………………………….. 115
3.5.4.5
pH value
……………………………………………... 115
3.5.4.6 Liquid limit and plasticity
3.6
…………………………… 115
Stabilization techniques ………………………………..……………… 117
3.6.1 Stabilizers …………………………..……………..………….... 117
3.6.2
Mix design and preparation of the mixtures …………....……… 118
3.6.2.1 Preparing the soil …………………………………….. 118
3.6.2.2
Primary test
………………………………………….. 119
vii
3.6.2.3 Preparing the design mixtures ……………………….. 120
2.6.3
Determination the optimum moisture content and dry density ... 120
3.6.3.1 Method
………………………………………………... 120
…………………………………………… 120
3.6.3.2 Instruments
3.6.3.3 Procedure
3.7
3.8
……………………………………………... 121
Making the stabilized compressed earth blocks ……………...………... 124
………………………………………..…………... 124
3.7.1
Equipments
27.2
Compressed earth block-making machine
3.7.3
Sizes of the blocks ……………………………………..……… 125
3.7.4
Preparing the materials, batches and block casting ……..……... 125
3.7.5
Preparation of specimens for permeability test …………..……. 129
3.7.6
Compressive strength test
…………..…………. 125
………………………………..……. 131
Method of measurements …………………………...............................… 133
3.8.1 Selection of tests
………………………..……….…………….. 133
3.8.2 The chosen tests block
3.8.3
………………………………………….. 133
Determination of the required number of the blocks and the
quantities of materials .................................................................... 134
3.8.4
Measurement and sizes ……………………………………......... 135
3.8.4.1
Dimensions and mass ……............................................. 135
3.8.4.2
Test procedure and calculations
3.8.4.3 Preparing blocks for tests
3.8.5
Dry compressive strength test
3.8.5.1 Principle of the test
……...……............... 136
…………………................ 137
…………………..……………… 138
…………………..……................. 139
3.8.5.2 Apparatus in common use
………………................… 139
3.8.5.3 Preparing the sample and making the specimen ............. 139
viii
3.8.6
Capillary test
……………………………………………..…….. 141
3.8.6.1 Objective of the test
....................................................... 141
3.8.6.2 Principle of the test
…………..…………..................… 141
3.8.6.3 Apparatus (special apparatus) ……..……..................… 141
3.8.6.4 Preparing the sample ……………………..................... 142
3.8.6.5 Procedure and calculations ……………….................... 143
3.8.7 Shrinkage test …………………………………………….……. 145
3.8.8
Water absorption test
3.8.9
Boiling test
……………………………………..…… 146
………………………………………………..…… 148
3.8.10 Permeability test
……………………………………………..… 149
3.8.11 Portable ultrasonic non destructive indicate test (Pundit)
….…. 151
CHAPTER 4- TESTS RESULTS
4.1
General …………………………………………………..…………….. 153
4.2
Result of sieving ……………………………………................................. 154
4.3
Properties of soil sample .......................................................................... 156
4.4
Test method
............................................................................................. 157
4.4.1 Optimum moisture content and dry density
................................. 158
4.5
Compressive strength ................................................................................ 161
4.6
Compressive strength test results .............................................................. 163
4.7
Water absorption results
4.8
Capillary test results …………………………………………….…….... 168
4.9
Boiling test results ………………………………………….…………... 170
…………….…………………….….……....... 166
4.10 Shrinkage test results ……………………………………….…………... 172
4.11
Permeability test results ……………………………………….………... 173
4.12
Portable ultrasonic test results (Pundit) …………….………………...... 174
ix
CHAPTER 5- ANALYSIS AND DISCUSSIONS
5.1
General ..................................................................................................... 175
5.2
Mechanical properties ............................................................................. 175
5.3
Blocks preparation
5.4
Mixing and moulding
5.5
Discussions of results .............................................................................. 179
5.5.1
................................................................................... 176
…......................................................................... 177
Compressive strength …………………...................................... 179
5.5.1.1 Stabilized compressed earth blocks
............................... 179
5.5.1.2 Stabilized manual cast earth blocks
............................... 182
5.5.1.3 Comparing compressive strengths between compressed
and manual cast stabilized earth blocks ………...….….. 184
......................................................................... 188
5.5.2
Water absorption
5.5.3
Compressive strength after absorption test ................................... 189
5.5.4
Capillary test
5.5.5
Compressive strength after capillary test .................................... 196
5.5.6
Boiling test ................................................................................... 202
................................................................................ 195
5.5.7 Compressive strength after boiling test
....................................... 203
5.5.8
Shrinkage test .............................................................................. 209
5.5.9
Permeability test
.......................................................................... 211
5.5.10 Portable ultrasonic test (Pundit) ………………..…………….…. 216
5.5.11 Density
………………………………………………….……… 216
…..…………………………….…… 217
5.6
Relationships with cement blocks
5.7
Relationships with lime blocks
5.8
Relationships with cement and lime blocks
5.9
Relationships with bitumen blocks ………….……….…………..…...… 232
5.10
Relationships with calcium silicate blocks ………...….….……....…...… 237
………….……….………………....….. 222
x
…………………………... 227
CHAPTER 6- CONCLUSIONS AND RECOMMENDATIONS
............................................................................................. 242
6.1
Conclusions
6.2
Recommendations for further research ................................................... 245
References
…………………………………………………………...………... 246
Appendixes
xi
LIST OF TABLES
Page
Table 1.1
Energy requirement to produce different building materials
(Kleespies, 1991)
3
Table 1.2
Embodied energy in BTU's required for the production and use
of various materials (Christensen)
5
Table 1.3
Comparison between five different wall types
8
Table 1.4
Characteristics of earth blocks (Al-Jadid, 2001)
9
Table 2.1
Chronological sequence of developments in building materials
(Reddy, 2004)
23
Table 2.2
The British standard range of particle sizes analysis of a soil
33
Table 2.3
Some typical properties of gravel, sands and silts (Bell, 1993)
35
Table 2.4
Summary of soil particles size (Stulz & Mukerji, 1988)
36
Table 2.5
Some common properties of laterite (Bell, 1993)
36
Table 2.6
Reports of soil particle size (Burroughs, 2001)
40
Table 2.7
Plasticity index and liquid limit values (Davison, 2000)
45
Table 2.8
Maximum permissible linear shrinkage (Maniatidis & Walker,
2003)
59
Table 2.9
Asphalt emulsion proportions for adobe soils
70
Table 2.10
An idea for good mixture for most blocks
77
Table 2.11
The proper composition for used in compressed earth block
(Patty & Minium)
79
Table 2.12
Example of a dry sieving result
80
Table 2.13
Some properties of compressed stabilized earth blocks versus
other walling materials (Adam & Agib, 2001)
87
Table 2.14
Classification of compression pressure machines
89
Table 2.15
Soil properties (soil sample from Hadhramout)
96
Table 2.16
Tests on various mud brick samples showed a crushing strength
varying from 0.6 (N/mm2) to 2.5 (N/mm2), 25 days
(Mubarak, 1988)
97
xii
Table 3.1
Quantities of the stabilized compressed blocks needed
134
Table 3. 2
Concrete and cement mortar quality based on Ultra sound
impulse velocity
151
Table 4.1
Determination of the particle size distribution
(samples A, B and C)
154
Table 4.2
Soil Properties
156
Table 4.3
Compressive strength results for the soil cement manual blocks
(10 % cement, 12 % water (O.M.C))
157
Table 4.4
Compressive strength results for compressed soil blocks
(Without any stabilizer, 12 % water (O.M.C))
158
Table 4.5
Compaction test results for soil mixed with the five percentages
of cement
159
Table 4.6
Compaction test results for soil mixed with the five percentages
of lime
160
Table 4.7
Compressive strength test results of different cement content
161
Table 4.8
Compressive strength test results of different lime content
161
Table 4.9
Compressive strength test results of different bitumen content
162
Table 4.10
Compressive strength test results of different calcium silicate
content
162
Table 4.11
Compressive strength results for compressed stabilized earth
for the different types of blocks (Average of 10 tested blocks)
164
Table 4.12
Compressive strength results of the manually prepared stabilized
blocks for the different types (Average of 10 tested blocks)
165
Water absorption of the different stabilized earth blocks (Average
166
Table 4.13
of 10 tested blocks)
Table 4.14
Capillary test results for the different types of stabilized earth
blocks (Average of 10 tested blocks)
168
Table 4.15
Boiling test results for the different types of stabilized earth
blocks (Average of 10 tested blocks)
170
Table 4.16
Shrinkage test results for the different types of stabilized earth
blocks (Average of 10 tested blocks)
172
xiii
Table 4.17
Permeability test results for the different types of stabilized earth
blocks (Average of 10 tested blocks)
173
Table 4.18
Pundit test results for the different types of stabilized earth
blocks at 180 days
174
Table 5.1
Results of the stabilized cement block
218
Table 5.2
Correlation between tests results of the cement block (R value)
221
Table 5.3
Results of the stabilized lime block
223
Table 5.4
Correlation between tests results of the lime block
(R value)
226
Table 5.5
Results of the stabilized cement and lime block
228
Table 5.6
Table 5.6: Correlation between tests results of the cement and
lime block (R value)
231
Table 5.7
Results of the stabilized bitumen block
233
Table 5.8
Correlation between tests results of the bitumen block (R value)
236
Table 5.9
Results of the stabilized calcium silicate block
238
Table 5.10
Correlation between tests results of the calcium silicate block (R
value)
241
xiv
LIST OF FIGURES
Fig.1.1
Earth material and construction around the world
2
Source: (Houben & Guillaud, 1994)
Fig. 1.2
Example from Yemen. Mud clay ancient palace, Tarim city
(Bradley, 1997) Source: Aga Khan Trust for Culture
Fig. 1.3
Egyptian mud-brick storage rooms (3200 years old) (CRATerreEAG) and cob buildings in Sa'dah, Yemen (Marechaux, 1998)
10
Fig. 1.4
Shibam, city in Wadi Hadhramout/Yemen (Doan, 2007)
11
Fig. 1.5
Clay buildings in New Mexico. Adobe is the most traditional
form of earthen construction in the US (Blanc)
(Source: Balderma, 2001)
12
Fig. 1.6
The CINVA-Ram hydraulic compressed machine
14
Fig. 2.1
Ruins of earth shelters (Egyptian mud-brick storage rooms, 3200
years) (Middendorf, 2001)
24
Fig. 2.2
Pressed block, cement stabilized (tourist information centre)
(Moor & Heathcote, 2002)
28
Fig. 2.3 (a)
An exhibition building in Janadryah, Saudi Arabia
(Joffroy, 1988) (Source: Baladerma, 2001)
29
Fig. 2.3 (b)
The mud brick mosque in the Mali
(Aldana) (Source: Baladerma, 2001)
29
4
Fig. 2.3 (c) Housing in Auroville, India, and Isère, France
Maïni and Joffroy (Source: Baladerma, 2001)
29
Fig. 2.4
The three-phase soil model (Whitlow, 1995)
31
Fig. 2.5
Laterite site in India [www.aurovillelandfund.org]
36
Fig. 2.6
Chelsea Flower Show exhibit wall, built by David Clark in 2000
(Photo by: David Clark)
38
Fig. 2.7
The range of particle sizes in the soil
39
Fig. 2.8
Sketch of a non-saturated porous material (Valkenborg, 2001)
40
Fig. 2.9
Block diagram of water – volume relationship (Davison, 2000)
41
Fig. 2.10
Volume-weight model
42
xv
Fig. 2.11
Typical proctor curve ( Legget, 1960; Chen, 1999)
44
Fig. 2.12
Plasticity index and liquid limit values (Davison, 2000)
46
Fig. 2.13
Atterberg limits (Davison, 2000)
46
Fig. 2.14
Diagram of particle intimacy around the O.M.C (Montgomery,
2002)
48
Fig. 2.15
Typical moisture-density relationship, O.M.C. for soil at
different compaction energies (B.S. 1377 part 4, 1990)
49
Fig. 2.16
Variation of water absorption rate with time for different cement
contents (Meukam, et al., 2002)
64
Fig 2.17
Unconfined, semi-confined and confined compaction
(Montgomery, 2002)
71
Fig. 2.18
Basics of compaction and the effected of compaction degree
72
Fig. 2.19 (a) Lower particle size distribution limits (Maniatidis & Walker,
2003)
78
Fig. 2.19 (b) Upper particle size distribution limits (Maniatidis & Walker,
2003)
78
Fig 2.20
Soil analysis figure showing particle sizes and clay fractions
(Gooding, 1993)
80
Fig. 2.21
Basic techniques of earthen construction (Houben & Guillaud,
1994)
82
Fig. 2.22
New methods; straw bale, earth bags and earth tires
83
Fig. 2.23
New rammed earth house
84
Fig. 2.24
The left picture shows the earth mix material being put in the
Ram while the right photo shows a block being ejected after the
compression cycle (Gore, 2000)
90
Fig. 2.25
Some of common used press machines
(Houben & Guillaud, 1994; Adam & Agib, 2001)
92
Fig. 2.26
Sultan Kathiri palace
One of the biggest clay buildings in the world
94
Fig. 2.27
Minaret Al Mihdhar, Town of Tarim
94
Fig. 2.28
The walled city of Shibam
95
xvi
Fig. 2.29
Wooden ring beams outside and inside the buildings
96
Fig. 2.30
New technology and the traditional method with natural wood
beams
97
Fig. 2.31
The steel beams, water pipes covered with plants and mud
finishing
98
Fig. 2.32
Preparing the mud (wetting the mixture of soil with straw)
99
Fig. 2.33
Preparing, casting and drying the mud-bricks -Tarim city
100
Fig. 2.34
New clay house (city of Tarim)
101
Fig. 2.35
New compressed earth block machine in the city of Sayu’n
102
Fig. 3.1
B.S. sieve set
111
Fig. 3.2
Mechanical sieve shaker
111
Fig. 3.3
Sieving test and soil particle sizes
113
Fig. 3.4
Part of laboratory tests for the soil
116
Fig. 3.5
Soil air-drying process
119
Fig. 3.6
Manual casting blocks using hand tamping
119
Fig. 3.7
A standard compaction machine
121
Fig. 3.8
Compaction method process for determining the dry density
moisture content relationship
123
Fig. 3.9
Tools and equipments used for blocks casting
123
Fig. 3.10(a ) Illustrating the procedure of preparing materials and casting the
stabilized compressed earth blocks
127
Fig. 3.10(b) Illustrating the procedure of block handling, drying and curing
128
Fig. 3.11
Trial of making cylinder specimens for permeability test
129
Fig. 3.12
Permeability fabricated instrument and samples making
130
Fig. 3.13
Block sides (length, width and height)
136
Fig. 3.14
Earth blocks are cured in the ventilated oven
138
Fig. 3.15
The compressive strength machine
140
xvii
Fig. 3.16
Capillary set up test
142
Fig. 3.17
Capillary test and taking the result after absorption
144
Fig. 3.18
Measuring shrinkage
145
Fig. 3.19
Absorption test
146
Fig. 3.20
Section in a tested block showing the absorption of water
147
Fig. 3.21
Water tank boiling machine and water boiling
148
Fig. 3.22
Permeability test set up, nitrogen gas
150
Fig. 3.23
Pundit test
152
Fig. 4.1
Grading curve of the three samples and the proper area
155
Fig. 4.2
Manual cast blocks using hand tamping showing bad crumbled
edges
157
Fig. 4.3
Moisture content and dry density for the ratios of cement soil
mixture
159
Fig. 4.4
Moisture content and dry density for the ratios of lime soil
mixture
160
Fig. 4.5
Compressive strength for the five categories hydraulically
compressed stabilized blocks
164
Fig. 4.6
Compressive strength of the manually prepared stabilized blocks
for the different types
165
Fig. 4.7
Water absorption of stabilized earth blocks of the different mixes
167
Fig. 4.8
Capillary ratio of stabilized earth blocks of the different mixes
169
Fig. 4.9
Boiling test result (water absorption ratio) for the different types
of stabilized earth blocks
171
Fig. 4.10
Shrinkage rate for the different types of stabilized earth blocks
172
Fig. 4.11
Permeability coefficient rate for the different types of stabilized
earth blocks
173
Fig. 4.12
Pundit results for the different types of stabilized earth blocks at
180 days
174
Fig. 5.1
Compressive strength for the five different types of hydraulically
compressed stabilized blocks
179
xviii
Fig. 5.2
Compressive strength for the manually prepared stabilized blocks
for the different types
182
Fig 5.3
Compressive strength of cement blocks for compressed and
manual blocks
184
Fig. 5.4
Compressive strength of lime blocks for compressed and manual
blocks
185
Fig. 5.5
Compressive strength of cement and lime blocks for compressed
and manual blocks
186
Fig. 5.6:
Compressive strength of bitumen blocks for compressed and
manual blocks
186
Fig. 5.7
Compressive strength of calcium silicate blocks for compressed
and manual blocks
187
Fig. 5.8
Water absorption for the different types of stabilized earth blocks
188
Fig. 5.9
Compressive strength of cement blocks
(Dry strength and strength after the water absorption test)
190
Fig. 5.10
Compressive strength of lime blocks
(Dry strength and strength after the water absorption test)
191
Fig. 5.11
Compressive strength of cement and lime blocks
(Dry strength and strength after the water absorption test)
192
Fig. 5.12
Compressive strength of bitumen blocks
(Dry strength and strength after the water absorption test)
193
Fig. 5.13
Compressive strength of calcium silicate blocks
(Dry strength and strength after the water absorption test)
194
Fig. 5.14
Capillary rate for the different types of stabilized earth blocks
195
Fig. 5.15
Compressive strength of cement blocks
(Dry strength and strength after the capillary test)
197
Fig. 5.16
Compressive strength of lime blocks
(Dry strength and strength after the capillary test)
198
Fig. 5.17
Compressive strength of cement and lime blocks
(Dry strength and strength after the capillary test)
199
Fig. 5.18
Compressive strength of bitumen blocks
(Dry strength and strength after the capillary test)
200
xix
Fig. 5.19
Compressive strength of calcium silicate blocks
(Dry strength and strength after the capillary test)
201
Fig. 5.20
Boiling absorption rate for the different types of stabilized earth
blocks
202
Fig. 5.21
Compressive strength of cement blocks
(Dry strength and strength after the boiling test)
204
Fig. 5.22
Compressive strength of lime blocks
(Dry strength and strength after the boiling test)
205
Fig. 5.23
Compressive strength of cement and lime blocks
(Dry strength and strength after the boiling test)
206
Fig. 5.24
Compressive strength of bitumen blocks
(Dry strength and strength after the boiling test)
207
Fig. 5.25
Compressive strength of calcium silicate blocks(Dry strength and
strength after the boiling test)
208
Fig. 5.26
Shrinkage rate for different types of compressed stabilized earth
blocks
209
Fig. 5.27
Permeability coefficient rate for the different types of stabilized
earth blocks
211
Fig. 5.28
Relation between the compressive strength of cement blocks
and the permeability coefficient
212
Fig. 5.29
Relation between the compressive strength of lime blocks
and permeability coefficient
213
Fig. 5.30
Relation between the compressive strength of cement and lime
blocks and permeability coefficient
214
Fig. 5.31
Relation between the compressive strength of bitumen blocks
and permeability coefficient
214
Fig. 5.32
Relation between the compressive strength of calcium silicate
blocks and permeability coefficient
215
xx
SIFAT-SIFAT KETAHANAN BLOK TANAH YANG STABIL
ABSTRAK
Tanah sebagai bahan binaan bangunan yang mudah diperolehi. Di negara-negara
membangun, pembinaan menggunakan tanah adalah lebih ekonomik dan berkesan.
Permintaan yang tinggi dengan sumber yang tidak terhad. Teknik pembinaan berasaskan
tanah secara tradisional seperti bata tanah liat tanpa bakar adalah lemah kepada air dan
retakan. Penyelenggaraan berterusan diperlukan bagi memastikan ianya sentiasa dalam
keadaan baik. Tesis ini menerangkan hubungan antara sifat-sifat tanah, beberapa penstabil,
kekuatan mampatan dan ketumpatan dari tanah yang diambil sekitar Pulau Pinang.
Menggunakan ‘CINVA-Ram Hydraulic Machine’, blok tanah termampat yang distabilkan
dengan 5 % setiap penstabil dibentuk. Blok-blok ini diuji pada 1, 7 dan 28 hari. Keputusan
ujian mampatan menunjukkan keputusan terbaik dan peratusan penstabil terbaik dipilih.
Peratusan-peratusan yang dimaksudkan adalah 10 % simen, 5 % kapur, 6 % (pra-campur
simen) bitumen dan 0.75 % (pra-campur simen) calcium silicate. Campuran 10 % simen dan
5 % kapur juga adalah dicadangkan. Ujian makmal dijalankan untuk menyiasat sifat-sifat
dan kebolehan blok-blok dalam cuaca tropika. Menggunakan perincian seperti dinyatakan
diatas, blok termampat distabilkan dihasilkan dalam lima kategori dengan lima tempoh
jangkamasa ujian (7, 28, 56, 90 dan 180 hari). Blok tanah yang dibuat secara manual juga
dihasilkan untuk dibandingkan prestasi dan kekuatan mampatannya antara blok termampat
dan tidak termampat distabilkan.
Keputusan menunjukkan peningkatan dalam prestasi, kekuatan mampatan dan ketahanan
blok. Kekuatan mampatan bagi blok tanah termampat pada 180 hari dengan komposisi
simen, campuran kapur-simen, calcium silicate dan bitumen adalah 13.2 N/mm2, 6.4 N/mm2,
16.3 N/mm2, 11.7 N/mm2, dan 12.6 N/mm2 manakala bagi cara manual 3.8 N/mm2, 1.5
N/mm2, 3.5 N/mm2, 2.8 N/mm2, dan 3.4 N/mm2. Kekuatan mampatan terbaik adalah dari
xxi
campuran simen-kapur dan ini adalah campuran baru dan rekabentuk bancuhan yang
dipertingkatkan. Bagi ujian penyerapan air dan ujian kapilari, campuran simen-kapur
menghasilkan keputusan terbaik pada hanya 5.9 % dan 5.7 %, ketelapan manakala 8.6 %
bagi blok simen-bitumen didalam air mendidih dimana ia agak baik bagi blok tanah.
Penstabilan dan pemampatan mengurangkan kadar pengecutan. Bacaan tertinggi adalah 0.43
% pada 180 hari untuk blok kapur dan yang lainnya adalah lebih rendah. Ujian
kebolehtelapan gas juga dijalankan menggunakan saiz spesimen piawai. Ujian halaju
denyutan juga dijalankan pada umur 180 hari dan keputusan menunjukkan perhubungan
yang baik antara kekuatan mampatan dan halaju denyut daripada blok-blok yang diuji.
xxii
DURABILITY PROPERTIES OF STABILIZED EARTH BLOCKS
ABSTRACT
Earth as a building material is available everywhere. In developing countries, earth
construction is economically the most efficient means to house the greatest number of
people with the least demand of resources. Traditional earth construction techniques such as
adobe bricks suffering from water attack and cracks, thus they need continuously maintain it
in order to keep them in good condition. This thesis studies the relationships between soil
properties, several stabilizers and their compressive strength and density using local soil
taken from site at city of Penang in Malaysia.
Using CINVA-Ram hydraulic machine, stabilized compressed earth blocks were cast with
the five percentages of each stabilizer, and these blocks were tested at (1, 7 and 28 days).
Compressive strength results showed the best result and the appropriate percent of each
stabilizer were chosen. These percentages are 10 % cement, 5 % lime, 6 % (of the used
cement) bitumen and 0.75 % (of the used cement) calcium silicate. A mix of 10 % of cement
and 5 % of lime is recommended. Laboratory tests were conducted to investigate the
properties and performance of the blocks in its normal conditions. Using the previous details
the required stabilized compressed earth block were cast for the five block categories and for
five periods of testing (7, 28, 56, 90 and 180 days). Manually cast blocks were also done to
compare the performance and the compressive strength between compressed and uncompressed stabilized earth blocks.
Results revealed improvements in the blocks compressive strength and durability. The
compressive strength of the compressed earth blocks at 180 days prospectively for cement,
lime with cement, calcium silicate, and bitumen, were 13.2 N/mm2, 6.4 N/mm2, 16.3 N/mm2,
11.7 N/mm2 and 12.6 N/mm2 while it were 3.8 N/mm2, 1.5 N/mm2, 3.5 N/mm2, 2.8 N/mm2
and 3.4 N/mm2 for the manually cast blocks. The highest compressive strength results were
derived from the mixture of cement and lime blocks and this was a new mixture and
xxiii
improvement mix design, while the cement blocks gave optimum compressive strength by
manual casting. For water absorption test and capillary test the cement and lime mix blocks
gained the best results of only 5.9 % and 5.7 % respectively, while it was 8.6 % for cement
and bitumen blocks in the boiling test, which are quite good for earth blocks. Stabilizing and
compressing decrease the blocks shrinkage. The highest was 0.43 % at 180 days for the lime
blocks and other categories were lower. Gas permeability was also tested using standard size
of specimens. Portable ultrasonic test (Pundit) was also carried out for the 180 days of age
and the results showed good relationship between compressive strength and pulse velocity of
these stabilized blocks.
xxiv
CHAPTER ONE
INTRODUCTION
1.1
Introduction
This chapter briefly outlines the motivation for this work and explains why
research in this area is of interest to human beings. It focuses on aspects of the
traditional adobe, characteristics of the raw material and why they are important for
human needs. It also focuses on the need for development to face new requirements
and the need to understand the properties of building materials to increase the
strength and durability of earth blocks against destructive effects. This is very
important towards a more sustainable construction of walling and buildings.
1.2
Background
1.2.1 Why use earth for building?
Many benefits that are offered by earth construction are often underutilized
in the developed world where the use of earth as a low-embodied material is often
the case (Middendorf, 2001).
Historically, earth has been the most widely known and used building
material in construction and probably has been the most important of all building
materials (Legget, 1960). According to Middendorf (2001) recorded cases of the
use of earth bricks dates back to Mesopotamia “around 8000 BC”. Recent reports
indicated that, about half of the world’s populations are still living in earth
buildings (McHenry, 1984; EBAA. Australia). Of all urban housing units
worldwide there are about 25 % that does not conform to building regulations while
18 % are considered non-permanent structures (Habitat, 2001).
1
Earth as a building material is available everywhere and exists in many
different compositions. It is most efficiently used in developing countries to house
the greatest number of people with the least demand. The world map below shows
the distribution of buildings units using earth material and construction around the
world (Fig. 1.1). However, it must be noted that earth buildings are not a
phenomenon only of the Third World countries, but also in developed countries
(EBA New Zealand, 1998).
Fig.1.1: Earth material and construction around the world
Source: (Houben & Guillaud, 1994)
It is important to ensure that the materials used in construction meet all the
specification in every respect. This means that all relevant properties must be
checked properly before construction (Tuffin, 2007).
There are many benefits of earth buildings. For example, earth structures are
completely recyclable, so sun-dried bricks return to the earth without polluting the
soil (Rigassi, 1995). Using earth for such environmental-friendly buildings will be a
strong component in the future of humankind (Bossel, 1998; Hochella, 2002). In
addition, energy requirement to produce adobe block is only 5 (kWh)/cubic meter,
2
while it is about 1000 (kWh)/ cubic meter for fired brick and 400-500 (kWh)/ cubic
meter for concrete (Table 1.1).
Table1.1: Energy requirement to produce different building materials (Kleespies, 1991)
Building materials
Cement
Concrete
Fired brick
Adobe
Unit
Sack
Cubic meter
Cubic meter
Cubic meter
Energy (kWh)
50
400 - 500
1000
5
Generally, people are re-discovering the benefits of having earth walls in
developing countries (Middendorf, 2001). This is because better properties can be
obtained by using additives to the earth material. In addition, earth construction is
possible with a wide variety of building methods. Egyptian architect, Hassan Fathy
(1973) argues that housing design should not be based solely on imported forms,
but rather on traditional forms of architecture as well.
In 1998, 88% of Yemeni families were living in villages and in their own
made houses. There are many economical, demographic and social problems
associated with housing issues as the need for housing in Yemen which is
increasing rapidly (Al-Jahdari et al., 1998). For example, there is a clear shortage of
houses compared to the number of families. A study about the housing situation in
the Republic of Yemen has indicated that the average yearly demand has been
about 149,500 units, from 1992 to 2005 (Al-Jahdari et al., 1998).
In cities of developing countries, there are many problems such as
homelessness and unsuitable living conditions (Ballerino, 2002). This can be
observed everywhere, especially in developing countries such as Manila, Mexico
City and Jakarta as well as the industrialized countries. This has resulted in millions
of squatter camps made of plastic sheets, flattened cans or cardboard, spread on
3
strips of land beside canals and railways, sometimes even in the shadows of highrise "low-cost" housing. In these areas, such as in Calcutta, the cost of
manufacturing building materials is high (Reddy, 2004).
Actually, most developing countries are facing a real housing deficiency
(Harison & Sinha, 1995). Therefore, there is an urgent need to construct and build
houses that are more durable at a low cost. In this regard, clay masonry has a long
and illustrious record of providing durable and attractive buildings (Fig.1.2).
Recently, the technology of traditional earth construction has undergone
considerable developments that have enhanced earth’s durability and quality as a
construction material for low-cost buildings (Adam & Agib, 2001).
Fig. 1.2: Example from Yemen. Mud clay ancient palace, Tarim city
(Bradley, 1997) Source: Aga Khan Trust for Culture
Buildings made from earth materials can be a way towards sustainable
management of the earth’s resources. They can be put in place using simple
machinery and human energy. Earth buildings avoid high-energy costs in the initial
4
manufacturing and construction period, in their use as homes, and eventually in
their recycling process (Temeemi & Harris, 2004). Thus, it is not surprising that
many people value earth construction for the above reasons for their durability
(Reddy, 2004) and for the following qualities:
1. The principal reason for using earth is its excellent sustainability characteristics.
These include, the efficient use of finite resources, minimizing pollution and waste
and low carbon emissions especially in industrial countries (Little & Morton,
2001). In comparison with other materials, adobe and rammed earth, buildings
reflect the embodied energy required for the production and use of various
materials. In comparison to brick ad concrete, adobe bricks have the less embodied
energy (McHenry, 1984) (Table 1.2).
2. Adobe blocks do not use organic resources for firing and it does not consume any
non-renewable energy. Thus, it has environmental advantages and does not
contribute to deforestation. In addition, adobe blocks use very little water, which
are essential for people (Little & Morton, 2001).
3. Adobe blocks have good economical advantages. It requires no major financial
transport costs. It is often comparable in cost with or more economical than other
competing technologies. Adobe blocks require only simple production and
application tools (moulds, presses, light shuttering and masonry tools, etc.).
Table1.2: Embodied energy in BTU's required for the production and
use of various materials (Christensen)
Common brick
13,570 BTU
Concrete block
29,018 BTU
Earth (Adobe) block (mechanized production)
Source: Book earth guidelines
http://greenbuilder.com/sourcebook/EarthGuidlines.html
5
2,500 BTU
By understanding the characteristics of soil we can promote the use of earth
as an ecological on-site building material (Adam & Agib, 2001). Many types of soil
are suitable for use as building materials. To improve their quality, one needs to
identify the characteristics of the soil and its appropriateness for using in building
construction. Besides the addition and removal of certain constituents, several tests
need to be carried out (Stulz & Mukerji, 1988; Kerali, 2001).
There are also problems that need to be solved to increase durability, for
example, the problem of rain penetration in buildings. According to Jefferson, rain
penetration results in condensation of water vapour on cool surfaces leading to
damp walls (Ritchie, 1960). Damp walls have become more common since the
1920s. This is because of changes in materials use and construction methods
(Crawford, 1978).
The most significant part of the physical structure is the walling
constituents, which is about 60 % (Agevi, 1999). Thus, it makes greater sense to
concentrate work on low-cost walling. Dwelling cost can be split into a number of
separate areas.
Block pressing machines have been designed and are used for "self-built
initiatives" such as the CINV-Ram machine (manual block press) and the Brepak
(hydraulically assisted block press) (Montgomery, 2002). These presses are not too
expensive as they do not require high quantities of cement for adequate
performance and their maintenance is not complex.
6
1.2.2 Low cost
Soil is widely available and in some parts of the world, especially remote
areas, it is the only material available (Adam & Agib, 2001). Soil is suitable for
construction in many building components as it uses only about 1% of the energy
required to manufacture and process the same volume of cement concrete.
Furthermore, using soil requires less specialized equipment compared to other
forms such as brick walls and cement block, which cost more than soil cement
walls (Bush, 1984; Adam & Agib, 2001).
However, production cost should not be the only basis of comparison with
other building materials. The expensive additives that are used to manufacture the
walls and the transportation cost of materials also greatly affect the cost of low-cost
walling. Moreover, good quality compressed stabilized earth blocks do not require
external renderings. The large block size results in less labor and a lower amount of
mortar is needed for block, which will result in additional savings being made.
Another important factor is the equipment and tools needed for the manufacture of
compressed and stabilized blocks. Earth block can be made locally and a variety of
equipment can be used to construct low-cost residential houses. Pressed block
making machines such as the CINVA-Ram and similar portable hand-operated
machines are used in many places around the world. They are good examples of
tools for making pressed block (Bush, 1984; Houben & Guillaud, 1994). In
addition, study in Italy showed the difference quality and feasibility in wall types
and the cost of the stabilized earth blocks was the lowest (see Table 1.3).
7
Table 1.3: Comparison between five different wall types
Dimension (cm)
Cost analysis
Cost ($/m2
Thermo physical analysis
Transmittance (W/m2oC
Front thermal capacity (KJ/
m2oC
Delayed heat transmission (h)
Attenuation factor (-)
Machimbre
(not
insulated
Stabilized
earth
blocks
28*9.5*14
17.42
19.32
8.72
1.792
2.421
1.687
1.674
131.9
207.6
253.0
53.0
197.1
2.88
0.85
5.39
0.63
4.88
0.56
1.66
0.93
5.46
063
Concrete
blocks
Hollow
bricks
Solid
bricks
40*20*20
33*18*18
30*6*15
12.94
14.97
2.116
Source: (Mattone et al., 2005)
The sight to the characteristics of building with the earth material can
assume many important advantages like the great spreading and very low cost or
free material in some places around the world, the environment, saving the energy.
According to Al-Jadid (2004), some of those characteristics are important for the
developing countries more than others, other characters are important to the
advanced and western countries and some of these characteristics are important to
all countries (see Table 1.4).
8
Table 1.4: Characteristics of earth blocks (Al-Jadid, 2004)
The most advantages of built
with earth
The low cost and availability.
Degree of importance to the counties
Developing countries
Western and Industrial
High
Mid.
Less
High
Mid
Less
*
*
Limited pollution and depletion of
*
environmental resources.
*
Ease of construction with earth
material.
*
*
Reduced unemployment of
*
unskilled labor.
Variation in constructions techniques
*
*
and methods.
Savings in transportation cost.
*
Saving in energy consumption
*
Engineering characteristics of
*
*
*
*
earth material.
Easing recycled of earth products.
*
*
*
In spite of all the advantages this material is still unsuitable for use in many
countries around the world, mainly attribute to the disadvantages of this material
and lack of information on the material properties. Compressed stabilized earth
blocks can be used as a construction material for housing. The purpose of the
stabilizer is to prevent softening of the soil on absorption of moisture (Harison &
Sinha, 1995). The earth-compressed blocks are widely used around the world in the
last 30 years not only in the third world countries but also in the developed
countries like USA, French, Canada and Australia.
9
1.2.3 Adobe blocks
Adobe has a great heritage of sustainable clay buildings around the world
and has special experts in this area. The adobe block follows the heritage of the
traditional architecture of numerous countries using local materials (Little &
Morton, 2001) (Fig. 1.3). In some wet and humid areas where unburned bricks are
used, roofs are designed to shade the mud wall. This means that the building is
only one or two stories high. These places have cheap wood for the roofs. Wood is
usually very expensive in many countries, and is not suitable for low-cost houses
(Middendorf, 2001). In Yemen (for example), the biggest problem in the unburned
clay buildings is the water effect and the brick strength (Lewcock, 1986).
Fig. 1.3: Egyptian mud-brick storage rooms (3200 years old) (CRATerre-EAG) and
cob buildings in Sa'dah, Yemen (Marechaux, 1998)
1.2.3.1 Traditional adobe
Traditional adobe is made out of soil and straw and found mostly in older
homes. The straw prevents cracking and adds strength. Adobe buildings can last
easily for about 100 years or more if the walls are dry and are kept away from
wicking up water from the earth. Thus, maintenance is important since moisture can
get in through cracks (Fransworth, 1999; Middendorf, 2001).
10
1.2.3.2 Traditional Yemeni clay buildings
The tradition of mud-brick architecture in the Hadhramout region in Yemen
offers a unique source of cultural and technical knowledge. It is rich in its variety;
for example, the traditional houses in Shibam city are built of mud-brick on stone
foundations (Fig. 1.4). Walls are tapered on the outside from about 1 m thick at the
bottom to less than 30 cm at the top (Lewcock, 1986). The top one or two levels of
all the buildings are protected from rain by white lime plaster. Photo 1.3 also shows
historic buildings in Yemen, which have been recognized by UNESCO (Hughes,
1991). The recognition is based on the following reasons:
i)
Unusual soil properties
ii)
Unique construction techniques in an arid climate
iii)
The preservation of the building
Fig. 1.4: Shibam, city in Wadi Hadhramout/Yemen (Doan, 2007)
11
1.2.4 New techniques
In Yemen, over an enormous geographical area, there are many modern
earth buildings which have been constructed through new techniques. Worldwide,
the new earth buildings added new methods to develop new technologies. Most of
these methods were derived from traditional methods (Middendorf, 2001). These
methods will be discussed in Chapter Two of the Literature Review.
In industrial countries such as in the Southwest U.S.A, the very rich class
often uses adobe, while in "developing" countries; its use is mostly confined to
those who are too poor to have access to other building materials. Adobe is
appropriate in areas, which are labor-rich and capital-poor; because it is labor
intensive, using local materials and simple tools (Kennedy, 1997). Fig. 1.5 is an
example of its wide appeal.
Fig. 1.5: Clay buildings in New Mexico. Adobe is the most traditional
form of earthen construction in the US (Blanc) (Source: Balderma, 2001)
More than two billion people live in buildings constructed of earth (Little &
Morton, 2001; Middendorf, 2001). To improve the quality, the selection of building
materials should meet the local conditions of life by improving on existing
structures or by building new structures. In the past, improving and developing the
12
natural materials using new technology has created substitute materials (Ballerino,
2002).
1.2.4.1 Stabilized soil
Stabilization is necessary to achieve a lasting structure from local soil. The
local material properties determine the appropriate stabilization method
(Montgomery, 1998). Stabilization techniques can be broken down into three
categories, (Houben & Guillaud, 1994).
- Mechanical stabilization: compacting the soil and changing its density,
compressibility, permeability and porosity.
- Physical stabilization: changing the texture properties of the soil. It can be done
by controlling the mixture of different grain fractions, drying or freezing, heat
treatment and electrical treatment.
- Chemical stabilization: changing the properties of the soil by adding other
chemicals or additives. This happens either by creating a matrix, which binds or
coats the grains or by a physico-chemical reaction between the grains and the
additive materials (Gooding & Thomas, 1995). Many additive materials can be
used to stabilize the soil (Hoben, 1994; Kerali, 2001).
The compressive strength of the soil can be improved multifold by using the
right stabilization method. This will also improve its durability by increasing its
resistance to erosion and water damage. The main categories of binders used for
earth construction are Portland cement, lime, bitumen, natural fibers and chemical
solutions such as silicates (Houben & Guillaud 1994) as also outlined in the
Australian Standard and SAZS 724:2001 Zimbabwe Standard.
13
1.2.4.2 Compressed earth blocks
The compressed earth block is the modern descendent of the molded earth
block. The earth-compressed blocks became widely used around the world in the
last 30 years or more, not only in third world countries, but also in developed
countries like the USA, France, Canada and Australia. Machines were first used to
compress earth as early as the 18th century. In France, architectural purposes came
into effect only in 1952 by Engineer Raul Ramirez of the CINVA centre in Bogota,
Columbia, designed the ClNVA-Ram press machine. This was used throughout the
world (Rigassi, 1995) especially in developing countries in Africa, South America
and Asia (Guillaud et al., 1995; Heathcote, 2002; Morel et al., 2007).
Compressed earth blocks are made by using a variety of machines. Some,
like the CINVA-Ram were invented for compressing earth blocks (Fig. 1.6).
Compressed earth block technology offers an alternative kind of building
construction which is more accessible and of high quality. The compressed earth
block is one of the most important "modern building materials" which has enough
production flexibility to let it be integrated into both formal and informal sectors of
structural activities (Rigassi, 1995). Some hydraulic machines were developed to
get blocks similar to concrete blocks (Bahar et al., 2004).
Fig. 1.6: The CINVA-Ram hydraulic compressed machine
14
1.2.5
Water
Water is preamble up from the ground, erodes the bases of earthen walls,
affecting them to crumble and fall away quickly. Since, water is the main enemy of
all earthen construction (McHenry, 1984; Farnsworth, 1999), walls should be
sealed to prevent all kind of moisture: either it is from an external source (rainfall,
soil humidity, ground water) or internal source (used water and pipes) (Megyesi,
2003).
In view of this, there are several issues that have to be considered like the
weakness of these blocks against the water effects and the need for this cheap
material in other areas that are not arid but are wet and cold. These areas may also
need housing projects, which utilize low cost buildings for its greater population.
So, there is a need for a comprehensive study to determine the properties, the right
mixture, suitable new stabilizers and modern technology for government buildings
and housing projects.
Other problems that ought to be taken into account are:
1.
Use of the traditional plaster is not enough to protect the mud bricks especially
against water and humidity.
2. The adobe block should be improved to acquire more durability and strength for
new requirements and wider openings and to decrease the drying period.
3. In traditional earth bricks, wall thickness relies on brick size for each level.
There are no special sizes for joints or corner demands like half or quarter block.
4. Traditional clay construction does not facilitate building of the balconies and its
ability to bear heavy loads is low.
15
5. The traditional construction systems show a weakness and an inability of
conjunction especially in the joints and corners, which need maintenance in many
cases.
1.2.6
Critical summary
Good production could be performed by increasing compressive strength
and using improved curing (Kerali, 2001). Further improvements in material
performance will help to outweigh sloppy production practices. A lot of research
work has been done in the development of local low and stabilized soil area
(Guettala, 2002; Bahar et al., 2004).
National and international standards have also been developed for these
procedures such as New Zealand standard 1998 and Standards Australia handbook
2002 (Walker 1996; Morel et al., 2007). The test methods of earth walls vary from
country to country because of the varied weather conditions. They are also not
based on the evaluation of field performance (Heathcota, 1995). A number of
guidelines and publications that explain various aspects of earth wall construction
and testing have been produced as well (Burroughs, 2001). The influences of soil
and stabilizers on the qualities of the stabilized material have also been examined
(e.g. Bryan 1988; Osula, 1996).
In spite of all these, little work has been done on durability tests such as
water permeability, capillary and water absorption. The variety of soils from one
region to another is a strong reason for this. The effect of compaction methods on
the chemical and mechanical properties needs further studies (Bahar et al., 2004).
16
Strength testing and quality control of compressed earth blocks has often
followed procedures developed for fired clay and concrete block units (Walker,
1996). However, consensus on the test procedure for compressed earth blocks is
little (Morel et al., 2007). Previous studies have reported on the compressive
strength characteristics of compressed earth blocks (Walker 1997; Reddy, 2003;
Morel et al., 2007). Thus, what is needed now is good empirical data to improve the
knowledge on soil stabilization for earth wall construction (Burroughs, 2001).
1.3
Scope of the study
This study will focus on wall building materials that can offer better quality
structures and faster construction solutions that will be economical. These aspects
need to be clarified through literature regarding building materials properties and
wall building systems. Thus, it will investigate traditional and innovative
techniques that have been used successfully in the Republic of Yemen. It will focus
on techniques that have relevance to climatic, technical and cultural reasons.
This study will also examine the stabilized compression of full size
compressed earth block samples and determine the relationships between soil
properties (gradation, plasticity, and moisture), stabilizer types (asphalt, cement,
lime, etc.), stabilizer quantities, and stabilized earth qualities (density and
compressive strength) and develop new durable compressed blocks for housing
construction.
17
1.4
Problems statement
The main drawback of soil material is the need for continuous maintenance
and the lack of durability and resistance to water (Bahar et al., 2004). Most
researches done in this area has always focused on processed durability or strength.
All aspects should be considered to produce sustainable, durable, safe and
environmental friendly homes and buildings. However, earth construction suffers
from shrinkage cracking, low strength and lack of durability (Bahar et al., 2004;
Guettala et al., 2006). In addition, most earthen materials are unsuitable for homes
of more than two stories, as they are unable to carry the load of the upper walls.
The lower walls would need to be thicker than the upper walls in the same building.
Thus, labor costs would be very high indeed (Farnsworth, 1999).
The challenge of modern and new requirements, the need for sustainable
low cost buildings to house people and the lack of knowledge in this area justify the
need for more research to be focused on the strength and durability of earth block.
18
1.5
Research objectives
This research project is aimed to:
1- gain a better understanding of the characteristics of the material.
2- determine which variables are of greatest influence in the production of
compacted samples.
3- define the structural and performance characteristics of laterite that can be
expected of additives for stabilizing the blocks.
4- define a laboratory mixture design and testing protocol to ensure the necessary
properties and develop new quantitative criteria for soil assessment, selection and
stabilization.
5- improve earth blocks durability as well as improve the strength for low cost
and sustainable houses.
6- determine the percentages of stabilizer, which depend on the soil quality and
the particular requirements and determine the most effective stabilizer for the
chosen soil.
7-
give an overall view of the qualities and varieties of the use of clay as a
building material in combination with some stabilizers.
Most methods are not concerned with durability especially strength and
shrinkage aspects. The objective of the second part of this project is to take the
findings from the material analysis and develop a systematic method for block
production using the beneficial aspects of hydraulic compaction machine.
19
This study is an attempt to improve building material. It focuses on the
properties and the performance of the stabilized compressed block. One purpose of
this study is to summarize information on the basic characteristics of soil and on the
stabilization and compaction.
1. 6
Hypothesis
Clay is good and strong enough to be used in buildings and housing projects
without causing any environmental problems. However, we need to extract its
characteristics and apply new technologies.
1. Experimental results should give or show directions for some points of longer
spans, wider openings, and thinner walls for multi stories by using compressed
earth blocks.
2. Casting and testing stabilized compressed earth blocks in humidity and hot
weather will prove that this technology is suitable in tropical areas as well as in arid
areas.
3. Is laterite soil in Malaysia suitable for compressed earth blocks for building
construction? Should Malaysia start thinking in this area as an option for future
housing demands?
4. Durability and strength should improve and shrinkage should reduce with a
good stabilizer.
New techniques should be used in developing countries such as Yemen to change
the material properties for wide spread use, new requirements needs and low-cost
projects.
20
1.7
Layout of thesis
The body of this thesis consists of seven chapters. The organization of the
chapters is as follows:
Chapter one
This chapter presents the history, problems in the area of this study
background and the need for this research. This chapter also summarises aims and
objectives of the research and presents examples of traditional buildings.
Chapter two
This chapter deals with various issues and research, which are relevant to
this study. It starts by tracing the historical background of building with earth
materials to explain the importance of this area to mankind. In addition, new work
in this area is discussed with some examples from around the world.
Soil
properties, classification indicators, additive materials, stabilization principles and
theoretical concepts of compressed stabilized earth blocks, mix designs and curing
methods are also described. Effective factors and compaction methods are also
presented. New technology used in stabilization and compression block machines is
also explained in this chapter. This chapter also discussed the main concepts of
durability in blocks and reviews the wide store of knowledge accumulated in this
aspect.
Discussion on a field study in Yemen is also included. It shows the heritage
clay cities and some of its mud brick technology. It focuses on traditional clay
building technology in Yemen and the properties of the local materials, common
stabilizers, and the need of the new techniques and its suitability for Yemen’s
buildings. This chapter also includes pictures of traditional buildings.
21
Chapter three
This chapter describes the structure of the thesis, the main experimental
design used and the sample preparation. Methods used for laboratory tests, mixingwater content, moulding pressure, curing conditions and presents the laboratory
tests that were done for the intended blocks with the varieties of the blocks age.
Chapter four
This chapter presents the results of all the experiments that were carried out
and the necessary data to support the conclusions of the experiments. This chapter
also presents the comparison of the properties and performance of blocks that
represent the core of the experimental work in this research.
Chapter five
This chapter discusses the results, the correlation and the different types of
compressed stabilized earth blocks for all periods of this study.
Chapter six
The final chapter of the thesis integrates and summarises the study. It
provides conclusions, recommendations and highlights the implications of the
research findings and identification of areas for further research are given at the end
of this chapter.
22
CHAPTER TWO
LITERATURE REVIEW
2.1
Introduction
Modern earth building is alive and well spread over an enormous
geographical area using numerous different methods of construction. The new earth
buildings developing worldwide have generally utilized the good aspects of the
traditional method while adding aspects and technologies. Today Adobe brick
construction has been partially adapted to economical projects. In Mesopotamia,
some cases of earth brick construction are as far as 10,000 BC (Heathcote, 1995;
Burroughs, 2001; Smith, 2004). Historically some of the building materials are new,
while others are very old and started with human shelter as shown in Table 2.1
(Reddy, 2004).
Table 2.1: Chronological sequence of developments in building materials (Reddy, 2004)
Material
Period
Mud, stones, wood/thatch
Prior 8000 BC
Sun dried bricks
6000 BC
Pottery products
4000 - 8000 BC
Burnt bricks
4000 BC
Lime
3000 BC
Glass
1300 BC
Iron products
1350 BC
Lime-pozzolana cement
300 BC - 476 AD
Aluminum
1808 AD
Portland cement
1824 AD
Plastic
1862 AD
23
From the past to the present day, earth seems to be the material of choice.
Mud brick that was made of alluvial soils were mixed with cereal straws. It gave man
his first durable construction material and took many forms, such as adobe, rammed
earth and straw-clay (Houben & Guillaud, 1994; Smith, 2004). Earth architecture has
also deep roots in all old civilizations, the Middle East, Iran and the cradle of the
Sumerian civilization in Iraq (Fig. 2.1). At Shibam in South of Yemen, there are
more than ten stories high of cob buildings (Houben & Guillaud, 1994). Nowadays,
unbaked earth buildings shelter about thirty percent of the world’s population
(Houben & Guillaud, 1994; Middfort, 2001; Megyesi, 2003).
Fig 2.1: Ruins of earth shelters (Egyptian mud-brick storage rooms, 3200 years)
(Middendorf, 2001)
24
web tierra