Project 462

24/B, Elizabeth St
MANDURAH WA 6210
27 October 2014
Head of Department
Department of Civil Engineering
Curtin University of Technology
Kent St, BENTLEY WA 6102
Dear Sir,
I have pleasure in enclosing my project titled "Properties of Hydrated Cement Paste
Containing Microsilica and Nano Iron Oxide" as a requirement of the course for the
Bachelor of Engineering (Civil & Construction) Degree.
Yours faithfully,
M. W. H. Tun

Department of Civil Engineering
Project Title
PROPERTIES OF HYDRATED CEMENT PASTE
CONTAINING MICROSILICA AND NANO IRON OXIDE
by
Maung Wai Hin Tun
14376452
OCTOBER 2014

Civil Engineering Project 461 & 462 Properties of Hydrated Cement Paste
Containing Microsilica and Nano Iron Oxide
Curtin University – Civil Engineering
i
Maung Wai Hin Tun
Project Documentation Sheet
Title: Properties of Hydrated Cement Paste Containing
Microsilica and Nano Iron Oxide
Author: Maung Wai Hin Tun
Date: 27th
October, 2014
Supervisor: Dr. Salim Barbhuiya
ABSTRACT: Nanotechnology means any technology performed at the nanoscale that has
applications to the real world. Due to the development in the studying of the nano-mechanics
field, technology has been improved from Micro to Nano scale in the measurement of
mechanical properties of cement powders with nano-scale minerals additives. Researchers
who are working in the field of finding the better quality in the properties of materials
concerning with nano-sized particles have studied and reported the effects of those materials
after adding the nano-particles and how they are useful to the industry of materials and also
useful to the construction industry. Compressive strength tests, Scanning Electron
Microscopy (SEM), X-Ray Diffraction (XRD) tests, Setting Times and Nano-indentation tests
are performed in order to study and determine the strength, surface topography of concrete,
morphology and mechanical behaviors such as elastic modulus and hardness of hydrated
cement paste by partially replacing with Micro-silica (SiO2) and Nano-iron oxide (Fe2O3)
particles. Seven mixtures are designed with different content percentages of nano and micro
particles. The tests were performed at the age of 28 days of curing, except compressive
strength tests which were performed at 3, 7, 28 and 56 days for all mixtures. Results from all
those designated tests revealed that partially replacing with 2 and 3 percentage of nano-iron
oxide particles in the cement paste provides the higher strength for both early age and later
age hydration, durability, quick initial setting times and high stiffness C-S-H gel for modulus
of elasticity and hardness. And addition of 5 percent of nano-iron oxide particles decreases
the final setting time.

ii
Maung Wai Hin Tun
Table of Contents
Abstract …………………………………………………………………………………………… i
Table of contents …………………………………………………………………………………..ii
List of figures ……………………………………………………………………………………... iv
List of tables …………………………………………………………………………..................... vi
_________________________________________________________________
Table of Contents
CHAPTER 1 .......................................................................................................................................... 1
INTRODUCTION................................................................................................................................. 1
1.1 General......................................................................................................................................... 1
1.2 Background.................................................................................................................................. 1
1.3 Aim and Objectives..................................................................................................................... 2
1.4 The structure of the Thesis......................................................................................................... 3
CHAPTER 2 .......................................................................................................................................... 5
REVIEW OF THE LITERATURE..................................................................................................... 5
2.1 Nanotechnology in Concrete ...................................................................................................... 5
2.2 Review of Works Done by Others Researchers........................................................................ 7
2.2.1 Heat of Hydration................................................................................................................. 7
2.2.2 Workability and Setting Time............................................................................................. 7
2.2.3 Strength................................................................................................................................. 8
2.3 Nano-indentation on Cementitious Materials......................................................................... 11
CHAPTER 3 ........................................................................................................................................ 13
MATERIALS AND METHODS........................................................................................................ 13
3.1 Materials .................................................................................................................................... 14
3.1.1 Hydrated Cement Paste..................................................................................................... 14
3.1.2 Nano-Iron Oxide Particles (Fe2O3) ................................................................................... 16
3.1.3 Micro-silica Particles (SiO2) .............................................................................................. 17
3.2 Methods...................................................................................................................................... 19
3.2.1 Preparing the Concrete Samples....................................................................................... 19
3.2.2 Compressive Strength Test of Hydrated Cement Mortars............................................. 26
3.2.3 Cutting and Resting the Concrete Samples for Nano-indentation Process................... 29

iii
Maung Wai Hin Tun
3.2.4 Scanning Electron Microscopy (SEM) tests..................................................................... 33
3.2.5 X-Ray Diffraction Test....................................................................................................... 35
3.2.6 Nano-indentation Tests...................................................................................................... 36
3.2.7 Setting Time Tests.............................................................................................................. 56
CHAPTER 4 ........................................................................................................................................ 60
RESULTS AND DISCUSSIONS ....................................................................................................... 60
4.1 Compressive Strength Tests..................................................................................................... 60
4.1.1 The Results of Compressive Strength Tests..................................................................... 61
4.1.2 Discussion about Compressive Strength Results............................................................. 66
4.2 X-Ray Diffraction tests (XRD)................................................................................................. 71
4.2.1 The Results from X-Ray Diffraction (XRD) Tests .......................................................... 71
4.2.2 Discussion about the Results from X-Ray Diffraction.................................................... 73
(XRD) Tests.................................................................................................................................. 73
4.3 Scanning Electron Microscopy (SEM) Test............................................................................ 74
4.3.1 Results and Discussion of SEM Images............................................................................ 75
4.4 Setting Time Tests..................................................................................................................... 83
4.4.1 Results ................................................................................................................................. 83
4.4.2 Analysis ............................................................................................................................... 84
4.4.3 Discussion of Setting Times Results.................................................................................. 86
4.5 Nano-indentation....................................................................................................................... 87
4.5.1 Results and Analysis........................................................................................................... 88
CHAPTER 5 ...................................................................................................................................... 102
CONCLUSION.................................................................................................................................. 102
REFERENCE .................................................................................................................................... 104
APPENDIX A: NANO-INDENTATION RESULTS OF MIXTURE 1 ....................................... 109
APPENDIX B: NANO-INDENTTAION RESULTS OF MIXTURE 2........................................ 119
APPENDIX C: NANO-INDENTTAION RESULTS OF MIXTURE 3 ....................................... 129
APPENDIX D: NANO-INDENTTAION RESULTS OF MIXTURE 4 ....................................... 139
APPENDIX E: NANO-INDENTTAION RESULTS OF MIXTURE 5........................................ 149
APPENDIX F: NANO-INDENTTAION RESULTS OF MIXTURE 6........................................ 159
APPENDIX G: NANO-INDENTTAION RESULTS OF MIXTURE 7 ....................................... 169

iv
Maung Wai Hin Tun
LIST OF FIGURES
Figure 3.1: Nano-Iron Oxide Partilces .............................................................................................. 17
Figure 3.2: Micro-silica Particles....................................................................................................... 19
Figure 3.3: Mixing Nano-Iron Oxide Particles with Required Amount of Water before
Sonication............................................................................................................................................. 21
Figure 3.4: Water Mixed with Nano-Iron Oxide Particles in Sonicator ........................................ 22
Figure 3.5: Sonication ......................................................................................................................... 22
Figure 3.6: Plastic Moulds.................................................................................................................. 23
Figure 3.7: Mixing of Cement with Water, Micro-Silica and Nano-Iron Oxide Particles............ 24
Figure 3.8: Concrete blocks after 24 Hours of Casting and before Demoulding .......................... 25
Figure 3.9: Typical Concrete Blocks after Demoulding Process..................................................... 25
Figure 3.10: Typical Procedure of Concrete Block inside Compressive Strength Testing Machine
............................................................................................................................................................... 28
Figure 3.11: Typical Concrete Blocks after Crushing for Compressive Strength Test ................ 28
Figure 3.12: Collected Small Pieces of Concrete after Compressive Strength Test...................... 30
Figure 3.13: Cutter in Nano-Laboratory .......................................................................................... 30
Figure 3.14: Cut Samples before Resting with iso-propyl............................................................... 31
Figure 3.15: Samples inside of Oven.................................................................................................. 32
Figure 3.16: Desiccator to Keep the Samples.................................................................................... 33
Figure 3.17: Typical Performance of SEM Tests by laboratory Operator.................................... 35
Figure 3.18: Samples after 24 Hours of Casting............................................................................... 40
Figure 3.19: Grinder/ Polisher for Nano-Indentation...................................................................... 41
Figure 3.20: Manual Grinding Process ............................................................................................. 42
Figure 3.21: Manual Checking of Sample Thickness by Using Vernier Caliper........................... 43
Figure 3.22: Bottle of EpoThin Epoxy Hardener............................................................................. 44
Figure 3.23: Bottle of EpoThin Epoxy Resin .................................................................................... 44
Figure 3.24: Vacuum........................................................................................................................... 46
Figure 3.25: impregnated Liquid Cup inside the Vacuum.............................................................. 46
Figure 3.26: Pouring the Impregnated Liquid to the Samples inside the Vacuum....................... 47
Figure 3.27: Sample marked with Square Shaped around 4 Sides................................................. 48
Figure 3.28: Base of Polisher before Polishing Process.................................................................... 49
Figure 3.29: Placing the Samples in the Rings of Polisher .............................................................. 50
Figure 3.30: Bottle of MetaDi Fluid................................................................................................... 51
Figure 3.31: Bottles of 9, 6, 3 and 1 Micro meter Used in Polishing Stage..................................... 51
Figure 3.32: Bottles of 0.25, 0.1 Micro Meter and Master Liquids Used in Polishing Stage........ 52
Figure 3.33: Final Ready Sample for Nano-Indentation ................................................................. 53
Figure 3.34: The Machine for Nano-Indentation ............................................................................. 55
Figure 3.35: Picture showing the inside of Nano-indentation Machine ......................................... 55
Figure 3.36: Testing of Nano-Indentation......................................................................................... 56
Figure 3.37: Setting Time ................................................................................................................... 59
Figure 4.1 38: Compressive Strength results at 3 Days ................................................................... 62

v
Maung Wai Hin Tun
Figure 4.2 39: Compressive Strength Results at 7 Days .................................................................. 62
Figure 4.3 40: Compressive Strength Results at 28 Days ................................................................ 63
Figure 4.4 41: Compressive Strength Results at 56 Days ................................................................ 63
Figure 4.5 42: Graph of Compressive Strength (MPa) Vs. Concrete Curing Days ...................... 64
Figure 4.6 43: Charts of Compressive Strength (MPa) Vs. Concrete Curing Days...................... 65
Figure 4.7 44: Concrete Block of Mixture 3 after Compressive Strength Test ............................. 67
Figure 4.10 47: Graph of Intensity vs. Angles of Degree in 2 Theta for XRD Tests ..................... 72
Figure 4.11 48: SEM of Mixture 1-1.................................................................................................. 75
Figure 4.12 49: SEM of Mixture 1-2.................................................................................................. 75
Figure 4.13 50: SEM of Mixture 2 - 1................................................................................................ 76
Figure 4.14 51: SEM of Mixture 2 -2................................................................................................. 76
Figure 4.18 55: SEM of Mixture 4 – 2 ............................................................................................... 78
Figure 4.26 63: Initial and Final Setting Times for Mixtures 1 to 7 ............................................... 85
Figure 2.27 64: Elastic Modulus of Mixture 1 .................................................................................. 88
Figure 4.34 71: Hardness of Mixture 1.............................................................................................. 95

vi
Maung Wai Hin Tun
LIST OF TABLES
Table 2.1: Summary of Other Works................................................................................................ 10
Table 3.1 2: Test Ages and Permissible Tolerance........................................................................... 27
Table 3.2 3: EpoQuick resin and Hardener in ml ............................................................................ 39
Table 3.3 4: EpoThin Resin and Hardener in ml ............................................................................. 43
Table 4.1 5: Compressive Strength Test Results .............................................................................. 61
Table 4.2 6: Initial and Final Setting Time Results.......................................................................... 83

1
Maung Wai Hin Tun
CHAPTER 1
INTRODUCTION
1.1 General
Nanotechnology means any technology performed at the nanoscale that has applications to the
real world. Due to the development in the studying of the nano-mechanics field, technology
has been improved from Micro to Nano scale in the measurement of mechanical properties of
cement powders with nano-scale minerals additives such as limestone, fly ash, silica fume,
ground granulated blast furnace slag, high reactivity metakaolin, iron oxide and so on in
recent years. [1] Nowadays, such minerals additives are widely used in industry to replace
partially the cement materials in construction to develop the properties, strength, and
workability and setting time of cement.
1.2 Background
Most of the previous studies show that they were performed by the addition of nano sized
powders without the addition of micron-sized particles such as mineral additives to increase
the compactness and strength enhancement of composites. [2] Other researchers studied the
effects and mechanical behaviors of hydrated cement paste with different mineral admixtures
by preparing various content percentages of those mineral admixtures with fixed water
cement binder ratio.

2
Maung Wai Hin Tun
1.3 Aim and Objectives
As nano-mechanical studies are needed to develop fundamental understanding of interfacial
phenomena on a small scale [3], analyzing and studying on the materials of concrete in Nano
scale is also needed in Civil Engineering field in order to achieve more effective and more
satisfactory quality in the future of Engineering. The purpose of the project report is to
analyze and study the Nano-mechanical behavior and properties of hydrated cement paste
which are, hardness and elastic modulus of deformation by adding Micro-silica and Nano-Iron
Oxide particles to improve the ways of controlling the friction, traction, lubrication and
reducing the surface damage such as wear, and contact fatigue in cement. As Nanotechnology
is more detailed into the size, we can study the failures of concrete in details for concrete
structure to improve the industry of construction technology in Civil Engineering. The final
purpose of the study is to advance in properties of materials and properties of concrete.
 Nano-indentation method has used in order to determine the surface properties and
nano-mechanical properties such as modulus of elasticity at maximum load, hardness
at maximum load, displacement at maximum load and coefficient of variation of
hydrated cement paste containing micro-sillica and nano iron oxide particles with
different proportions at the age of 28 days strength. And Nano-indentation is a test
method which is used to record and determine the surface properties on every range of
materials whether it is soft, hard, brittle or ductile with the design of providing the
high quality, accurate and repeatable nanometer results. [3] Indentation is very useful
to determine the surface properties and mechanical behavior of cement bulk since
cement paste itself is a heterogeneous material. The process can be done by using the
Agilent Technologies Nano Intender G200 machine.
 Another approach technique in order to achieve the nano-mechanical behavior of
hydrated cement paste is by performing compressive strength tests for the ages of 3
days, 7 days, 28 days and 56 days are also performed in order to study the strength of
concrete with different content percentages of micro-silica and nano-iron oxide
particles to determine and report the amount of deformations and compressive strength

3
Maung Wai Hin Tun
of concrete at different early ages. The process can be done by using the Universal
Testing Machine (UTM) or Instron Testing Machine or MCC8 Testing Machine.
 Scanning Electron Microscope Test (SEM) which uses a focused beam of high-energy
electrons to generate a variety of signals at the surface of solid specimens is required
to perform. [4] SEM test is an engineering and scientific laboratory test which uses
electrons instead of light to form an image to study and to produce images of the
composition and structure of cement paste containing Nano Iron Oxide particles and
Micro-silica for the samples of 28 days strength.
 Moreover, X-ray Diffraction (XRD) which also known as X-ray crystallography test is
also need to be completed to determining the atomic and molecular structure of a
concrete to provide detailed information on the structure and physical properties of
concrete. This test is also only used for the samples of 28 days strength.
 Initial and final setting time tests are also performed to characterize how the various
percentage contents of hydrated cement paste with micro-silica and nano-iron oxide
sets by using the Vicat needle or the Gillmore needle. The setting times methods
require initial set and final set based on the time at which a needle of particular size
and weight either penetrates a cement paste sample to a given depth or fails to
penetrate a cement paste sample.
1.4 The structure of the Thesis
This thesis is structured as follows. Chapter 2 reviews literature on the nano-technology and
reviews of works done by other previous researchers concerning about the heat of hydration,
workability, setting times and strength of hydrated cement pastes containing nano-iron oxide
particles with specified water binder ratio. Moreover, Chapter 2 also reviews the other
previous works on nano-indentation of cementious materials.

4
Maung Wai Hin Tun
In Chapter 3, materials and methods which were used in the laboratory in order to determine
the mechanical properties of hydrated cement paste are divided into two parts and explains the
details of all the properties and effects of the materials which were used and also explains the
details of every procedures and methods in order to meet the objectives and aim of the project.
Pictures are also used to explaining about methods for better understanding.
In the follow chapter which is Chapter 4, the results from every test and method are stated and
analyze them by using the corresponding analyzing methods and discuss the reasons behind
of every predominant result and also every detail of the obtaining results. The bar charts and
graphs are used in order to analyze and discuss helpfully.
The next chapter is the final chapter to explain the understanding of the project and to add
some recommendations of the project based on the knowledge and results of every test and
works. And that chapter is Chapter 5 to conclude the thesis.

5
Maung Wai Hin Tun
CHAPTER 2
REVIEW OF THE LITERATURE
Nanotechnology deals with small structures or small sized materials. The typical dimension
spans from subnanometer to several hundred nano-meters. A nanometer (nm) is one billionth
of a meter. Materials in this size range exhibit some remarkable specific properties and
functions which is the transition from atoms or molecules to bulk form takes place in this size
range. [5] Nano-particles have a high-surface area to volume ratio providing high-chemical
reactivity. However, due to the enormous increase in surface area per unit volume in the case
of nanoparticles, very strong reactive properties can be obtained. Nanotechnology helps in
producing materials with prospective properties for engineering. Scientists reported that nano-
particles can improve the smart materials which develop properties such as durability,
mechanical performance, thermal, electrical and conductivity insulation and so on. [6] The
addition of nano-particles to the cement paste can have important implications for the
hydration and micro-structure of the cement paste such as increasing in the initial hydration
rate, porosity reduction inside the form of the paste and also development in the mechanical
behaviors of the cement paste itself. [7]
2.1 Nanotechnology in Concrete
Concrete itself is the most ubiquitous material in the world and also is a nanostructured,
multi-phase, composite material that ages over time. [8] It is composed of an amorphous
phase, nanometer to micrometer size crystals, and bound water. [9] The properties of concrete
exist in, and the degradation mechanisms occur across, multiple length scales (nano to micro
to macro) where the properties of each scale derive from those of the next smaller scale. The
amorphous phase, calcium–silicate–hydrate (C–S–H) is the ‘‘glue” that holds concrete
together and is itself a nanomaterial. [10]

6
Maung Wai Hin Tun
There are two main parts in nanotechnology which are nano-science and nano-engineering,
sometimes called nano-modification of concrete. While nano-science mostly deals with the
measurement and characterization of the nano and micro-scale structure of cement-based
materials to better understand how this structure affects macro-scale properties and
performance through the use of advanced characterization techniques and atomistic or
molecular level modelling, nano-engineering comprises the techniques of manipulation of the
structure at the nano-meter scale to develop a new generation of tailored, multifunctional,
cementitious composites with superior mechanical performance and durability potentially
having a range of novel properties such as: low electrical resistivity, self-sensing capabilities,
self-cleaning, self-healing, high ductility, and self-control of cracks. [10] Concrete can be
nano-engineered by the incorporation of nano-sized building blocks or objects (e.g.,
nanoparticles and nanotubes) to control material behavior and add novel properties, or by the
grafting of molecules onto cement particles, cement phases, aggregates, and additives
(including nano-sized additives) to provide surface functionality, which can be adjusted to
promote specific interfacial interactions. [10]
Nano-engineering, or nano-modification, of cement is a quickly emerging field. [10]
Synthesis and assembly of materials in the nano-meter scale range offer the possibility for the
development of new cement additives such as novel superplasticizers, nanoparticles, or nano-
reinforcements. [10] Methodologies for hybridization and grafting of molecules allow for the
direct manipulation of the fundamental structure of cement phases. [10] These techniques can
be used effectively in a approach to control concrete properties, performance, and degradation
processes for a superior concrete and to provide the material with new functions and smart
properties not currently available. [10] Engineering concrete at the nanoscale can take place in
one or more of three locations, which are in the solid phases, in the liquid phase, and at
interfaces, including liquid–solid and solid–solid interfaces. [10] While nano-engineering of
cement-based materials is seen as having tremendous potential, nonetheless, several
challenges will need to be solved to realize its full potential, including the proper dispersion
of the nanoscale additives, scale-up of laboratory results and implementation on larger scale,
and a lowering of the cost benefit ratio. [10]

7
Maung Wai Hin Tun
Nano-Fe2O3 has been found to provide concrete with self-sensing capabilities as well as to
improve its compressive and flexural strengths. [10] The volume electric resistance of cement
mortar with nano-Fe2O3 was found to change with the applied load, demonstrating that mortar
with nano-Fe2O3 could sense its own compressive stress. Such sensing capabilities are
invaluable for real-time, structural health monitoring and for the construction of smart
structures as they do not involve the use of embedded or attached sensors. [10]
2.2 Review of Works Done by Others Researchers
Researchers who are working in the field of finding the better quality in the properties of
materials concerning with nano-sized particles have studied and reported the effects of those
materials after adding the nano-particles and how it is useful to the industry of materials and
also useful to the construction industry. And this paper also specifies the previous research
works done by the other researchers concerning with the addition of nano- iron oxide particles
on ordinary Portland cement particles in different content percentages.
2.2.1 Heat of Hydration
Khoshakhlagh et al. [2012] [11] studied the heat of hydration, up to 70 h, of cement pastes
modified with nano-iron oxide particles (NF). These particular research specifics that cement
was partially replaced with nano-iron oxide particles at the levels of 0%, 1%, 2%, 3%, 4% and
5% by weight and used the fixed water binder ratio. The final results showed that the addition
of nano-iron oxide particles accelerated peak times and dropped the rate values of heat. [11]
2.2.2 Workability and Setting Time
Nazari et al. [2010] [12] studied the workability of concretes modifies with nano-iron oxide
particles. And the researches was modified by partially replacing the cement with nano-iron
oxide particles at the levels of 0%, 0.5%, 1%, 1.5% and 2% by weight. And fixed water
binder ratio of 0.4 was used in this particular research program. [12] The final results specifies

8
Maung Wai Hin Tun
that a reduction in the workability with increasing the nano-iron oxide particles content. [12]
The same researcher also studied the initial and final setting times of concretes modified with
nano-iron oxide particles and cement was partially replaced with the nano-iron oxide particles
at the levels of 0%, 0.5%, 1%, 1.5% and 2% by weight and fixed water binder ratio of 0.4 was
also used. [12] The results proved that both initial and final setting times decreased with the
addition of nano-iron oxide which means that the setting times decreased as the content of
nano-iron oxide increased. [12]
2.2.3 Strength
Khoshakhlagh et al. [2012] [11] again studied the compressive strength, flexural strength and
splitting tensile strength at the strength ages of 2, 7 and 28 days. The research was modified
by replacing the cement particles with nano-iron oxide particles at the levels of 0%, 1%, 2%,
3%, 4% and 5% by weight. [11] The researcher used the fixed water binder ratio of 0.4 for all
mixtures and also used the fixed dosage of 1% by weight and the final results of all strength
showed that an increase with the addition of nano-iron oxide particles at all ages. [11]
However, the addition of 4% nano-iron oxide proved that the optimum content that gave the
highest strength. [11] The enhancement in the 28 days compressive strength was 20.57%,
31.33%, 52.53%, 71.83% and 67.1% with the addition of 1%, 2%, 3%, 4% and 5%
respectively. [11]
Li et al., [2004] [13] studied the compressive strength at the ages of 7 and 28 days of mortars
modified with nano-iron oxide particles. The research was accomplished by replacing the
cement partially with the nano-iron oxide particles at the levels of 0%, 3%, 5% and 10% by
weight. The researcher used the fixed water binder ratio of 0.5 and various dosages of water
reducing agents were employed for this particular research program. The results showed that
an increasing in the compressive strength with the addition of nano-iron oxide particles. The
enhancement in the 28 days compressive strength was 26%, 14.5% and 3.7% at the nano-iron
oxide contents of 3%, 5% and 7% respectively. The replacement level of 3% showed that the
highest compressive strength was followed by 5% and 10% respectively. [13]
Yazdi et al. [2011] [14] also studied the compressive strength and tensile strength at the ages
of 7 days of mortars modified by the partially replacement of cement with the nano-iron oxide

9
Maung Wai Hin Tun
content level of 0%, 1%, 3% and 5% by weight and used the fixed water binder ratio of 0.417
and various dosages of superplasticizer were employed. The final results showed that an
increase in both compressive strength and tensile strength with the addition of 1% and 3% of
nano-iron oxide while the addition of 5% decreased the strengths. The enhancement in the
compressive strength was 56.44% and 74% at the levels of 1% and 3% of nano-iron oxide.
[14]
Nazari et al. [2010] [12] again studied the compressive strength at the ages of 7, 28 and 90
days of concrete modified with nano-iron oxide particles. Cement was partially replaced with
NF at levels of 0%, 0.5%, 1%, 1.5% and 2%, by weight. Fixed w/b ratio of 0.4 was used. The
results showed an increase in the compressive strength with the addition of nano-iron oxide
particles, at all ages. 1% nano-iron oxide showed the optimum content which gave the highest
compressive strength. The enhancement in the 28 days compressive strength was 11.41%,
15.49%, 13.86% and 5.7% with the addition of 0.5%, 1%, 1.5% and 2% nano-iron oxide,
respectively. [12]
Nazari and Riahi [2011] [15] investigated the optimal nano-iron oxide content that gave the
highest splitting tensile strength, at ages of 7, 28 and 90 days, of concretes. Cement was
partially replaced with nano-iron oxide at levels of 0%, 0.5%, 1%, 1.5% and 2%, by weight.
Fixed w/b ratio of 0.4 was used. Two different curing conditions were employed, either water
curing or saturated limewater curing. The results showed that the splitting tensile strength
followed the order of 1% nano-iron oxide addition > 1.5% > 0.5% > 2% > 0%, for the
specimens cured in water. The enhancement in the 28 days splitting tensile strength was
33.33%%, 55.55%, 38.89% and 5.55% with the addition of 0.5%, 1%, 1.5% and 2% nano-
iron oxide, respectively. [15]
Oltulu and Sahin [2011] [16] studied the compressive strength, at ages of 3, 7, 28, 56 and 180
days, of mortars containing 5% SF modified with 0%, 0.5%, 1.25% and 2.5% nano-iron
oxide, by weight. Fixed w/b ratio of 0.4 was used. At ages of 3 and 7 days, the results showed
an increase in the compressive strength with the addition of 0.5% and 1.25% nano-iron oxide,
whilst the addition of 2.5% nano-iron oxide reduced the compressive strength. For the
remaining ages, the compressive strength increased with the addition of nano-iron oxide. The
addition of 0.5% nano-iron oxide showed the highest compressive strength, at all ages. The

10
Maung Wai Hin Tun
enhancement in the 28 days compressive strength was 24.43%, 15.82% and 14.28% with the
addition of 0.5%, 1.5% and 2.5% nano-iron oxide, respectively. [16]
A summary for the tests and the results of all those previous researchers are briefly stated in
the following table.
Table 2.1: Summary of Other Works
Author Nano content (%) Effect
Khoshakhlagh et al.
[2005] [11]
0, 1, 2, 3, 4 and 5 Increased the strengths
4% is the optimum
Li et al. [2004] [13] 0, 3, 5 and 10 Increased the compressive strength
3% is the optimum followed by 5% and
10%
0, 3 and 5 Increased the flexural strength
5% is the optimum
Yazdi et al.[2011]
[14]
0, 1, 3 and 5 1% and 3% increased the compressive and
tensile strength
5% decreased the compressive and tensile
strength
3% is the optimum followed by 1%
Nazari et al.[2010]
[12]
Nazari et al. Increased the compressive strength
1% is the optimum
Nazari and Riahi
[2011] [15]
0, 0.5, 1, 1.5 and 2 (Specimens cured in water)
Increased the splitting strength
1% is the optimum followed by 1.5%, 0.5%
and 2%
0, 0.5, 1, 1.5 and 2 (Specimens cured in saturated limewater)
Increased the splitting strength
2% is the optimum followed by 1.5%, 1%
and 0.5%

11
Maung Wai Hin Tun
0, 1.5, 2, 3, 4 and 5 Increased the splitting strength
4% is the optimum followed by 3%, 2% and
1%
Nazari et al.[2010]
[12]
0, 0.5, 1, 1.5 and 2 Increased the flexural strength
– 1% is the optimum
Oltulu and Sahin
[2011] [16]
0, 0.5, 1.25 and 2.5 (Mortar containing 5% SF)
– 0.5% and 1.25% increased the
compressive strength at 3 and 7 days
2.5% decreased the compressive strength at
3 and 7 days
Increased the compressive strength at the
remaining ages
– 0.5% is the optimum
Oltulu and Sahin
[2011] [16]
0, 0.5, 1.25 and 2.5 (Mortar containing 5% FA)
Decreased the compressive strength at 3 and
7 days
Increased the compressive strength at the
remaining ages
0.5% is the optimum
2.3 Nano-indentation on Cementitious Materials
Igarashi et al. [1996] [17] studied the bulk properties of cement paste at a sub-millimeter to
millimeter material length scale by using a Vickers indenter with a maximum penetration
depth on the order of h max ~ 10 .5 m.
Zhu et al. [1997] [18] used instrumented indentation to study (in a qualitative manner) the
mechanical properties of the interfacial transition zone in reinforced concrete.
Kholmyansky et al. [1994] [19] discusses the experimental methods for hardness
determination on fine-grained concrete. Velez et al. [2001] [20] reported nano-indentation

12
Maung Wai Hin Tun
results of the elastic modulus and hardness of the major clinker phases (C2S, C3S, C3A,
C4AF) 3, and Acker et al. [2001] [21] provided values for portlandite (CH=Ca(OH)2) and the
C-S-H gel for different C/S-ratio. These results were obtained on an ultra-high performance
cementitious composite material.
Constantinides and Ulm [2002] [22] confirmed the stiffness value for CH, and provided
stiffness values of the two types of C-S-H of an ordinary Portland cement paste prepared at a
water-cement ratio of w/c = 0.5, in a non-degraded and an asymptotically leached state. The
results were obtained with a Nano-Test 200 Berkovich indenter via arrays of equally spaced
nano-indentations at a fixed hmax.

13
Maung Wai Hin Tun
CHAPTER 3
MATERIALS AND METHODS
This chapter will divided into two categories and the first category is about the materials and
the later one is about the methods which are used in the laboratory in order to achieve the
mechanical properties of hydrated cement paste containing micro-silica and nano-iron oxide
particles.
fixed ratio of water cement binder and different content percentages of micro-silica and nano
iron oxide have decided for different cement mixtures in order to determine the different
nano-mechanical properties of hydrated cement while preparing and performing the
laboratory works. Seven different mixtures have prepared and same water cement binder ratio
of 0.4 is used for all mixtures.
However, the percentage contents of micro-silica and nano-iron oxide particles for each
mixture are as followed.
Mixture 1 – 100% of Ordinary Portland Cement (OPC)
Mixture 2 – 90% of OPC + 10% of Micro-silica (SiO2)
Mixture 3 – 90% of OPC + 9% of Micro-silica (SiO2) + 1% of Nano-iron oxide (Fe2O3)
Mixture 6 – 90% of OPC + 6% of Micro-silica (SiO2) + 4% of Nano-iron oxide (Fe2O3) and
Mixture 7 – 90% of OPC + 5% of Micro-silica (SiO2) + 5% of Nano-iron oxide (Fe2O2).

14
Maung Wai Hin Tun
As the topic of the thesis is about the hydrated cement paste, water cement binder ratio of 0.4
is used because adding 400ml of water in 1000g of cement particles helps the cement paste to
enhance more hydration in its. Using the same ratio of water cement binder to all mixtures
gives the relevant data and the results are easy to follow and analyze because all of those
mixtures have the same hydration.
3.1 Materials
This section will explain all three different materials and discuss their effects, usages, the
advantages and the reasons why they are used in this research project. There are only three
different types of major materials in this particular research project and they are hydrated
cement paste, micro-silica (SiO2) and nano-iron oxide (Fe2O3) particles.
3.1.1 Hydrated Cement Paste
Cement powder itself is anhydrous because it comes from a hot kiln, which is a thermally
insulated chamber. Cement is made by heating limestone (calcium carbonate) with small
quantities of other materials at 1450°C in a kiln, in a process known as calcination, where by
a molecule of carbon dioxide is liberated from the calcium carbonate to form calcium oxide,
or quicklime, which is then blended with the other materials that have been included in the
mix. [23] and [24] The result is a hard substance, called 'clinker', is then ground with a small
amount of gypsum into a powder to make 'Ordinary Portland Cement', the most commonly
used type of cement. [23]
Cement in construction can be distinguished into two main types which are hydrated cement
and non-hydrated cement. They are divided according to the presence water in the cement for
its ability. Studies of this paper only emphasize on hydrated cement paste. Hydration of
cement paste is the process, which the cement is mix with water. It involves many different
reactions often happening at the same time. As the reactions between the cement and the
water proceed, the products of the hydration process gradually bond together the individual
cement powder and water to form a solid paste which we called “hydrated cement paste” and

15
Maung Wai Hin Tun
the cement paste is analyzed by its porosity inside it, internal surface area, interaction between
solid substance and evaporated water and some other related properties.
Cement paste itself is a multi-phase material because it is a porous material composed of
calcium hydroxide (portlandite), aluminates and unhydrated clinker embedded into an
amorphous nano-structured hydration product which is called C-S-H gel. [25]
The C-S-H gel is the most important hydration product of cement (50-70% of the hydration
product by volume) with a characteristics length scale ranging from 1nm to 100nm. C-S-H
means “calcium silicate hydrate” with a variable composition which is the reason for the
hyphenated notation. Two different phases of C-S-H gel have been identified and a low
density of C-S-H (LD C-S-H) is formed during the first stages of the hydration. And a high
density of C-S-H (HD C-S-H) which is formed as the hydration process goes further.
And there are two types of hydration in cement which are through solution and topochemical.
As the through solution involves dissolution of anhydrous compounds to their ionic
constituents and formation of hydrates in solution, Topochemical is kind of solid state
hydration in which reactions take place directly at the surface of the anhydrous cement
compounds without going into solution. [26]
When water is added to cement, firstly the cement grans will dissolute in the water and it will
grow the iconic concentration which leads to the formation of compounds in solution. After
reaching a saturation concentration, compounds precipitate out as solids which are called
hydration products. After this, products form on or very near the surface of the anhydrous
cement. Formation of hydration products over time can lead to stiffening which is the loss of
workability, setting which is also known as solidification and hardening which is the stage of
achieving the strength.
In the studying of heat of hydration, heat of hydration in cement can be detrimental which is
thermal gradient leads to cracking in concrete and it is also helpful while heat provides
activation energy when concreting in cold weather and gain higher early strength. Half of the
total heat can be evolved in 1 to 3 days for ordinary Portland cement and a quarter at 7 days
and 83 to 91 percentages at 180 days. The rate of hydration is related to cement composition,
cement fineness, and cement content and casting temperature.

16
Maung Wai Hin Tun
3.1.2 Nano-Iron Oxide Particles (Fe2O3)
Various minerals additives such as fly ash and silica fume have been widely used in industry
of building and construction for cement composites not only for their environmental and
economic advantages, but also for the benefits in technical concerns. [2] Such technical
benefits are to fill in micro and macro voids and displaying the partial binder effects. A
significant increase in usage of such minerals additives has been observed over the past few
years and the result proved that the utilization of nano-sized materials in cement composites is
also growing. [2] The using of nano-sized particles are growing in these days because they are
expected to influence the kinetics and hydration of cement significantly and yield better
results in filling the voids of cement-based composites compared to the minerals additives due
to their larger surface area and greater electrostatic force. [2] The most commonly utilized
nano-powders used as minerals additives are nano-silica (SiO2), nano-aluminium oxide
(Al2O3) and nano-iron oxide (Fe2O3). [2]
Iron Oxide Particles (Fe2O3) is used to add to increase and improve the compressive strength
of the cement paste. Nano-powders are expected to influence the kinetics and hydration of
cement significantly and yield better results in filling of voids of cement-based composites
compared to the mineral additives due to their larger surface area and greater electrostatic
force. [11] Addition of nano-iron oxide particles to cement can decrease the workability and
both of initial and final setting times. [11] Moreover, it can also accelerate the peak times and
dropped heat rate values. [11] The addition of nano-iron oxide can also increase the
compressive strength and flexural strength. [11]

17
Maung Wai Hin Tun
Figure 3.1: Nano-Iron Oxide Partilces
3.1.3 Micro-silica Particles (SiO2)
There are two types of materials in the world which are crystalline and non-crystalline. Micro
silica or silica fume is very fine non crystalline material. It is an amorphous (non-crystalline)
polymorph of silicon dioxide and it is an ultrafine powder defined as the product of the silicon
and ferrosilicon alloy production and consists of spherical particles with an average particle
diameter of 150 nm. [27]
The main application is as pozzolanic material for high performance concrete. Silica fume is
an ultrafine airborne material with spherical particles less than 1 μm in diameter, the average
being about 0.1 μm which is approximately 100 times smaller than the average cement
particle. The unit weight or the bulk density of micro-silica depends on the metal from which
it is produced. [24] And the unit weight of micro-silica usually varies from 130 to 430 kg/m3
and the specific gravity of micro-silica is generally in the range of between 2.20 to 2.5. [24]
Micro-silica, (SiO2) has the features of small particle size, narrow particle size distribution,
and porous, large surface area and unsaturated residual bonds on its surface and shows high
reflectivity to long wave, visible light and ultraviolet ray. [28] Nano-particles of (SiO2) can
fill the spaces between particles as nano filler and it can decrease the setting time of mortar

18
Maung Wai Hin Tun
when compared to silica fume (SF) and also reduced bleeding of water and segregation, while
improving the cohesiveness of the mixtures in the fresh state. Moreover, adding (SiO2) and
(Fe2O3) as admixtures can change the physical and chemical properties of the concrete and it
also leads to save energy and reduce carbon dioxide CO2 emission. [28]
As mentioned above, micro-silica acts as filler and also as a cementitious material in the
preparation of cement paste. The small micro-silica particles can fill the spaces between
cement particles and the aggregate particles. Micro-silica also combines with calcium
hydroxide to form the additional calcium hydrate through the pozzolanic reaction. Both of
these actions give the final result of a denser, stronger and less permeable material. Micro-
silica has been used as an addition to concrete up to 15 percent by weight of cement, although
my proportions are 10%, 9%, 8%, 7%, 6% and 5%. [28] Addition of 15 percent resulted in the
potential exists for very strong, brittle concrete and it increases the demanding of water in a
concrete mix. However, usage of less than 5 percent will not typically require a water reducer
while the high replacement rates will require the use of a high range water reducer. [28]
The main advantages of using micro-silica as filler in cement paste are increasing the
durability, reducing the permeability of concrete and improvement the resistance to corrosion.
Moreover, Micro-silica increases the strength of concrete by 25% more and it is much cheaper
than cement. [24] Therefore, it can be say that it is very important from the economical point
of view. Micro-silica has been used with concrete by some industries because it can decrease
the air pollution in the building industry. Moreover, it can also decrease the voids in concrete.
Addition of silica fume reduces capillary and absorption and porosity because fine particles of
silica fume reacts with lime present in cement. [24]

19
Maung Wai Hin Tun
Figure 3.2: Micro-silica Particles
3.2 Methods
This section will explain all the different methods which are used in the laboratory in order to
achieve its main objectives and aim of the project which is determining the mechanical
properties of hydrated cement paste with micro-silica and nano-iron oxide particles. And this
section also discusses details processes, methods, effects, usages, the advantages and the
reasons why they are used in this research project.
3.2.1 Preparing the Concrete Samples
One of the very first steps in order to investigate the mechanical properties of hydrated
cement paste containing micro-silica and nano-iron oxide particles is preparation of concrete
samples with those particles.

20
Maung Wai Hin Tun
The following are the materials and items that needed to cast the cement samples.
 Touch N Tuff Dispensable Nitrite Gloves (wearing is necessary in order to avoid any
unwanted health concerns and for the safety point of view when touching the cement
powders, micro-silica and nano-iron oxide particles.
 P2 + Valve (UniSafe) face mask (wearing is also necessary in order to avoid any
unwanted health concerns and for the safety point of view when breathing the cement
powders, micro-silica and nano-iron oxide particles since iron oxides particles are very
harmful and can cause the cancer and micro-silica can cause headache, body ache and
digestion problems)
 Trowel and Spad (necessary not only when taking the cement powders and micro-
silica and also mixing the cement paste)
 Concrete Mixer
 Required amount of water for each mixture
 Plastic molding cubes with the sizes of 50x50 mm
 Cement powders – Ordinary Portland Cement (OPC)
 Miro-silica (SiO2) and
 Nano-iron oxide (Fe2O3) particles
Firstly, required amount of cement powders are taken from the concrete laboratory and weigh
on the weighing machine to get the exact required amount which is 4500 grams for 24 blocks
of 50x50mm in size of concrete. After weighing the amount of cement, weigh the necessary
amount of micro-silica particles for the mixtures of 2 to 7 and the amount of cement was
reduced by 10 percent for those mixtures of 2 to 7. Cement powders and micro-silica powders
can be available in the concrete laboratory anytime. Weighing the amount of nano-iron oxide
particles are also needed in the next step for the mixtures of 3 to 7. Please take note that the
weights of plastic bags or plastic buckets that those cement and other particles were placed
inside are already took out when they are weighing.
The amount of water required for those mixes are calculated as mentioned to the designated
plan in the introduction chapter which is 0.4 for water cement binder ratio. Therefore, 180 ml
of water is added for the 4500g of materials. Sonication process for nano-particles is
necessary before those nano-particles are mixed with cement and micro-particles. Therefore,
the necessary amount of nano-iron oxide particles is mixed with 180 ml of water and put them

21
Maung Wai Hin Tun
in a jar or a container and placed that container inside the sonicator for 20 minutes. Sonication
is a process in which sound waves are used to agitate particles in solution. And its disruption
is used in this research to mix solutions, speed the dissolution of a solid into a liquid by
breaking intermolecular interactions, to provide the energy for certain chemical reactions to
proceed and remove dissolved gas from liquids while the liquid is under the vacuum. The
main reason why sonication is used in nanotechnology is for dispersing nanoparticles evenly
in liquids.
During the sonication process for nano-iron oxide is carrying out, the cement powders and
micro-silica powders are mixed thoroughly and completely until the color of mixed powders
turned to grey as it is the color of micro-silica. And the mixed powders of cement and micro-
silica are added to the mixer bowl. After leaving the nano-iron oxide mixed liquid in the
sonicator for 20 minutes, they are added to the same concrete mixer bowel which has already
mixed cement and micro-silica powders inside in it.
Figure 3.3: Mixing Nano-Iron Oxide Particles with Required Amount of Water before
Sonication
Figure 3.3 shows that the required amount of nano-particles are mixed with required amount
of water in order to perform the sonication process as explained in the previous paragraph.

22
Maung Wai Hin Tun
Figure 3.4: Water Mixed with Nano-Iron Oxide Particles in Sonicator
Figure 3.5: Sonication
There are two stages in mixing. One is just 30 seconds and a minute at the faster speed. After
mixing all those materials thoroughly and completely together in the concrete mixer, the

23
Maung Wai Hin Tun
hydrated cement paste with micro-silica and nano-iron oxide are placed inside the plastic
molding containers which has the size of 50x50 mm and leave those molding containers filled
with those hydrated cement on the vibrator with the necessary rate and required duration to
enhance the compactness of the paste and also to have less voids and porosity inside it. Two
batches of cement have prepared in preparation of cement paste because of preparing 25
concrete cubes and small pieces of concrete blocks for nano-indentation.
Figure 3.6: Plastic Moulds

24
Maung Wai Hin Tun
Figure 3.7: Mixing of Cement with Water, Micro-Silica and Nano-Iron Oxide Particles
When casting process is done, all those casted samples are leave for about 24 hours in the
curing room which maintains the proper temperature and humidity to keep those samples.
Those samples can be taken out from curing room after 24 hours of casting and demolding
process is performing in the next stage. Demolding process is one of the longest processes to
carry out in this research program because those plastic molding containers are assembled
with numerous screws and unscrewing all of them is necessary in order to demold the cement
cubes. The interior faces of molding containers have to be applied with WD40 released agents
and wipe them thoroughly before the casting process was carried out. Otherwise, it is very
hard to get them out of those containers. And those plastic molding containers have to be
washed after demolding of cement cubes.

25
Maung Wai Hin Tun
Figure 3.8: Concrete blocks after 24 Hours of Casting and before Demoulding
Figure 3.9: Typical Concrete Blocks after Demoulding Process
All of those concrete cubes have to be labelled with correct designations (such as MIX-1-28
which means Mix 1 with 28 curing days) to perform the compressive strength tests and nano-
indentation tests. And placed them in the plastic container filled with water which is mixed
with Calcium Hydroxide particles because Calcium Hydroxide solution migrates to the
surface of the paving or concrete unit, where it evaporates. However, since only the water can

26
Maung Wai Hin Tun
evaporate, the entrained calcium hydroxide remains behind on the surface of the concrete unit.
Closed the lid of the plastic container and leave it in the curing room until the compressive
strength tests or nano-indentation tests are required to perform at the specified curing date.
3.2.2 Compressive Strength Test of Hydrated Cement Mortars
In order to achieve the main objective of the thesis, determining the compressive strengths of
all different mixtures of cement with different micro-silica and nano-iron oxide particles
content percentages at different curing strength days are necessary. This test provides a means
of determining the compressive strength of hydraulic cement and other mortars and the results
show the strength of concrete. Testing of compressive strength is needed for all different
seven mixtures at the age of 3, 7, 28 and 56 days.
The instron or the MCC8 testing machine is properly checked before any tests have been
taken out. Firstly, assemble the MCC8 testing machine for the cube specimens to get the tight
fitting and gives 2 inches of allowance to move up and down while operating the machine.
The upper bearing assembly is a spherically seated and hardened metal block is firmly
attached at the center of the upper head of the machine. The center of the sphere shall
coincide with the surface of the bearing face within a tolerance of addition or reduction of 5
percent of the radius of the sphere. The spherical portion of the bearing block and the seat that
holds the portion have to be cleaned before any tests are performed. And set the required
parameters which are applied compressive stress loads, extension distance for safety concerns
and everything necessary.

27
Maung Wai Hin Tun
The test ages and permissible tolerance of test specimens are as followed
Table 3.1 2: Test Ages and Permissible Tolerance
Test age Permissible Tolerance
24 hours ± ½ hour
3 days ± 1 hour
7 days ± 3 hours
28 days ± 12 hours
After taking the concrete samples out from the curing room in order to perform the
compressive strength test, those specimens has to be wiped to a surface dry condition, and
remove any loose sand grains or incrustations from the faces that will be in contact with the
bearing blocks of testing machine. After checking the faces by applying a straightedge and if
the appreciable curvatures are found, grind the faces to get the satisfactorily plane surfaces.
And also take note down the cross-sectional areas of the testing samples.
Place the tested samples carefully in the center of the metal block of the compressive strength
testing MCC8 machine and apply the compressive stress load of 0.25 MPa per second or 15
MPa per minute. This load rate is a relative rate of movement between the upper and lower
platens corresponding to a loading in the concrete cube sample with the range of 200 to 400
lbs/s which is 900 to 1800 N/s. When it reaches the maximum load after yielding, the platens
crushed the concrete cube sample and it is the failure load of that tested sample. The machine
indicates the maximum load which is also known as failure load and record for each tested
sample in kN. The tests were performed according to ASTM Standard of Compressive
Strength [29]

28
Maung Wai Hin Tun
Figure 3.10: Typical Procedure of Concrete Block inside Compressive Strength Testing
Machine
Figure 3.11: Typical Concrete Blocks after Crushing for Compressive Strength Test

29
Maung Wai Hin Tun
3.2.3 Cutting and Resting the Concrete Samples for Nano-
indentation Process
Small elongated pieces of concrete sample are casted when the concrete cubes samples are
casted. And those elongated pieces of concrete samples are needed to be cut to get the exact
size of 7x7 mm in order to perform the nano-indentation tests. They can be cut into sections
by using the precision diamond splitting wheel in the nano laboratory from Curtin University.
Placed the sample in the holder of the cutter and tighten them and rotate to get about 45
degree tilt for the blade to cut the sample easily. And set the correct dimensions for the cutting
size and speed of the blade before the cutting process has initiated. As soon as the process has
started, the blade will cut the sample with the designated speed until it is completely cut. The
cut samples are needed to be wiped as soon as it has cut in order to remove any water received
from the concrete cutter.
The small pieces of crushed samples of concrete samples from compressive strength test are
collected and rest them with the cut samples for nano-indentation in the isopropyl alcohol for
24 hours to reduce the hydration inside the samples. The lid of the container which keeps
those crushed samples with isopropyl alcohol has to be closed firmly in order to avoid
entering the moisture from atmosphere. Resting the concrete samples to be submerged in the
isopropyl alcohol can be only up to maximum of 5 days.

30
Maung Wai Hin Tun
Figure 3.12: Collected Small Pieces of Concrete after Compressive Strength Test
Figure 3.13: Cutter in Nano-Laboratory

31
Maung Wai Hin Tun
After taking out the crushed samples and the cut samples from isopropyl alcohol, they are
placed in a small plastic container and placed them inside the oven which has the heating
degree of 105 and above for maximum of only 24 hours. The main reason for leaving those
samples in the oven is also again to reduce and remove the hydration inside those small
samples. The heating ovens are located in the concrete laboratory from Curtin University.
Leaving the small samples in the oven for over 24 hours can have the results in cracking of
concrete samples. Therefore, it has to be very careful not to leave the samples inside the oven
for 24 hours and over.
Figure 3.14: Cut Samples before Resting with iso-propyl

32
Maung Wai Hin Tun
Figure 3.15: Samples inside of Oven
Those samples from the oven can be placed and rested inside the desiccator which is filled
with silica gel in the base to and maintain the quality and strength of required age, 28 days for
this project. Preserving in the desiccator is necessary in order to prevent hydration and
carbonation. The samples can be taken out from the desiccator anytime when it is necessary to
perform the Scanning Electron Microscopy (SEM) test or X-Ray Diffraction (XRD) test or
nano-indentation tests and the samples still keep the actual strength of the particularly
required age which is 28 days for this project.

33
Maung Wai Hin Tun
Figure 3.16: Desiccator to Keep the Samples
3.2.4 Scanning Electron Microscopy (SEM) tests
SEM has been used for the examination of composition and structure of concrete and become
an insightful tool for the microstructural analysis of concrete and its components. [30] There
are actually no standard procedures for the SEM analysis of concrete. However, it is a very
useful tool and technique to investigate the inside porosity, agglomeration, inside formation
and composition of concrete.
A Scanning Electron Microscope (SEM) is a tool for seeing the structures in micro-space (1
micron = 10-6m) and nano-space (1 nanometer = 10-9m). By using a focused beam of
electrons, the SEM reveals levels of detail and complexity inaccessible by light microscopy.
[30] SEM can magnify an object from about 10 times up to 300,000 times. [30] A scale bar is
often provided on an SEM image and the actual size of structures in the image can be
calculated form it. And the typical scanning electron microscope laboratory contains a
machine with three components which are the microscope column, the computer and ancillary
equipment. [30] The microscope column has the electron guns at the top, the column, down
which the electron beam travels, and the sample chamber at the base. [30] And the computer

34
Maung Wai Hin Tun
is for the microscope to drive with the additional bench controls and ancillary equipment is to
analyze the compositions. [30]
The scanning electron microscope (SEM) uses a focused beam of high-energy electrons to
generate a variety of signals at the surface of solid specimens. [30] The signals that derive
from electron-sample interactions reveal information about the sample including external
morphology (texture), chemical composition, and crystalline structure and orientation of
materials making up the sample. The SEM is also capable of performing analyses of selected
point locations on the sample; this approach is especially useful in qualitatively or semi-
quantitatively determining chemical compositions. [30]
The SEM also has much higher resolution, so closely spaced specimens can be magnified at
much higher levels. Because the SEM uses electromagnets rather than lenses, the researcher
has much more control in the degree of magnification. All of these advantages, as well as the
actual strikingly clear images, make the scanning electron microscope one of the most useful
instruments in research today.
It is critical that petrographer or operator or both be familiar with the SEM/EDX equipment,
specimen preparation procedures, and the use of other appropriate procedures for this
purpose. [30] The SEM provides images that can range in scale from a low magnification (for
example, 15×) to a high magnification (for example, 50 000× or greater) of concrete
specimens such as fragments, polished surfaces, or powders. [30] These images can provide
information indicating compositional or topographical variations in the observed specimen.
The operator place the samples inside the SEM machine and start to explore inside the
structure of hydrated cement samples with micro-silica and nano-iron oxide particles. The
exploration of inside the samples include moving the microscope anywhere in the sample and
magnifying the image with the size of 2µm and investigate the inside porosity, agglomeration,
inside formation and composition and topography of the sample. Take a picture if any
interesting structures or interesting agglomeration of nano-particles are found in Scanning
Electron Microscopy (SEM) test.

35
Maung Wai Hin Tun
Figure 3.17: Typical Performance of SEM Tests by laboratory Operator
3.2.5 X-Ray Diffraction Test
X-ray diffraction (XRD) is a powerful nondestructive technique for characterizing crystalline
materials. It provides information on structures, phases, preferred crystal orientations
(texture), and other structural parameters, such as average grain size, crystallinity, strain, and
crystal defects. X-ray diffraction peaks are X-ray Diffraction (XRD) and X-ray Reflectivity
(XRR) techniques produced by constructive interference of a monochromatic beam of x-rays
scattered at specific angles from each set of lattice planes in a sample. The peak intensities are
determined by the distribution of atoms within the lattice. Consequently, the x-ray diffraction
pattern is the fingerprint of periodic atomic arrangements in a given material.
The tests can be done by using The X-ray diffractometer which allows measurement of the X-
ray diffraction pattern from which the crystalline phases within the sample may be
qualitatively identified and the proportion of each phase may be quantitatively determined.
[31] X-rays are particularly hazardous. An X-ray diffractometer must be operated safely to
avoid serious injury or death. The X-rays are generated by high voltages, perhaps as high as
55 kV peak, requiring care to avoid serious electric shock. [31]

36
Maung Wai Hin Tun
XRD tests are only allowed to be held inside the XRD laboratory room in the Physics
Department from Curtin University. The crushed samples collected from compressive
strength test are sent to the Physics Department with the completely filled requested form and
request them to do the XRD test for the samples of this research project. And the laboratory
people from Physics Department return the corresponding results as soon as they finish of
performing the XRD tests on the samples of this research project.
3.2.6 Nano-indentation Tests
Nano-indentation has become a useful tool for the measurement of mechanical properties at
small scales and also becoming the greater technique for experimental studies of the
fundamental materials. [32] During the process of nano-indentation test, discrete events
including dislocation source activation, shear instability initiation and phase transformations
can be detected with the high resolution load displacement data.
The most common uses of nano-indentation in concrete material are for the measurement of
hardness and elastic modulus of concrete. The principal components in a nano-indentation
experiment are the test material, the sensors and actuators which are used to apply and
measure the mechanical load and indenter displacement, and the tip of the indenter. [32] The
indenter tip is made with diamond and formed into a sharp and symmetric shape such as the
three-sided pyramid. [32] The pyramidal shape is chosen at least in part for its nominal
geometric self-similarity, which makes for relatively simpler analysis using the methods of
continuum mechanics. [32] However, because of the very fine scale of nano-indentation
testing, imperfections in the pyramidal tip shape are of paramount importance in such
analysis, and much effort has been focused upon methods of characterizing and cataloging tip
shapes for more exact quantitative measurements. [32]
Elastic and plastic mechanical properties can be estimated at any scale within the limits
defined by the indenter dimensions and maximum penetration depth. Thus, instrumented
indentation is a versatile tool for material characterization, particularly at scales where
classical mechanical tests based on volume averaged stresses are inadequate.

37
Maung Wai Hin Tun
For hardness measurement of nano-indentation, the scan size is set to zero and normal load is
applied to make the indents. During this process, the diamond tip is pressed against the
surface of the sample continuously for about 2 seconds at different indentation loads. [33]
Nano-hardness can be calculated by dividing the indentation load by the projected residual
area of the indents. [33] The surfaces of the samples are scanned both before and after the
process of nano-indentation to obtain the final and initial surface topography at a low normal
load of about 0.3 µN by using the same diamond tip. For those of the areas larger than the
indentation region, they are scanned to observe the marks. [33]
The hardness value is obtained based on the projected residual area after imaging the indent.
Direct imaging of the indent allows one to quantify piling up of ductile material around the
indenter. However, it becomes very difficult to identify the boundary of the mark of
indentation accurately. [3] Therefore, it makes the direct measurement of the contact area
inaccurate. Dual capability of depth sensing technique is the better technique in the
determining of nano mechanical properties. [3] This indentation system is used to make load
displacement measurement and subsequently carry out the imaging of the indent. The
indentation system consists of a three plate transducer with electrostatic actuation hardware
used for direct application of normal load and a capacitive sensor which is used to measure
the vertical displacement. [3]
As explained above, a three-sided Berkovoich indenter with the tip radius of about 100nm is
generally used for the measurements. Sharper diamond tips with the angle of 60 to 90 degrees
and tip radii of 30 to 60 nm are employed for shallower indentation. Calibration of tip shaped
needs to be done in order to obtain the accurate relationship between the indenter depth and
the projected contact area. And the original unindented profile is subtracted from the indented
profile for the surfaces with roughness on the order of indentation depth.
In an indentation experiment, the tip is lowered close to the sample which is less than 100 µm
and scan the size and also scan the rate are selected. The tip is engaged to the surface of the
sample with a set point of 1 nA which is about 1 µN. The indentation rate can be varied by
changing the load and unload period.
In the preparation of the sample to perform the nano-indentation process, samples must
undergo a series of mechanical procedures to obtain a flat and smooth surface suitable for
indentation. [34] However, surface roughness cannot be fully avoided for cementitious

38
Maung Wai Hin Tun
materials since the mechanical preparation of the surface does not allow preparing better
surfaces with roughness smaller than several tens of nm. [34] Grinding and polishing
processes are necessary to produce residual stresses within the surface layers of the material
and cause local hardening. Evaluation procedures such as grinding and polishing methods
satisfy to obtain a flat surface with the ideal contact of an indenter. High surface roughness
can lead to improper area determination and higher local inelastic deformations.
A common source of the indentation size effect is improper estimation of the projected
indenter area. Each indenter has to be calibrated due to tip irregularities from its ideal shape.
Another reason based on the indentation process can be responsible for the size effect is the
development of dislocation. It is the nucleation of dislocations within the plastic zone under
the indentation area. Dislocations can be created in two ways which are for statistical reasons
and due to the indenter geometry (geometrically necessary dislocations). The presence of
dislocations can increase the yield strength of the material and therefore it increases the
hardness and elastic modulus.
3.2.5.1 Preparation of Samples for Nano-indentation
Preparation of the samples for nano-indentation involves a series of processes. It has several
stages to perform with care and cautiously in order to avoid becoming the unsuccessful
samples in preparation stages. Grinding and polishing steps are performed with finer abrasives
progressively in the preparation of nano-indentation samples. The main reason for preparation
the samples for nano-indentation is because surface roughness has to be less as much as it
needs to be since the research project is concerning with the cementitious materials and those
materials has to deal with the nano-indenter. However, since the cement-based materials are
performed with the different hardness, the difference in topography of concrete samples are
inevitable. However, keep grinding and polishing help to minimize the different in
topography.
Casting is the first step in the preparation of the samples for nano-indentation procedure. The
cut samples which have a size of 7x7mm keep in the desiccator are removed from desiccator
to start performing the preparation. It is essential to preserve the pore structure and to stabilize
the microstructure with epoxy resin before grinding and polishing .Epoquick (Epoxy) resin

39
Maung Wai Hin Tun
and Epoquick (Epoxy) hardener produced from Buehler from United State of America are
proportionally mixed inside a small cup until the formation of those two liquids become
thoroughly mixed and the color of the mix becomes as clear as crystal or cleaned water.
The amount required for those Epoquick resin and hardener in ml are as followed table.
Table 3.2 3: EpoQuick resin and Hardener in ml
Number of
Samples
4 5 6 7 8
Epoquick
Resin
40 50 60 65 80
Epoquick
Hardener
8 10 12 13 16
It has to be very careful when measuring the amount of those resin and hardener because the
casting of the samples will not be set in the next day if the required proportion amounts of
those resin or hardener are not accurate to the standard table. Also taking care of mixing is
needed to be very cautious because only resin can pour to the hardener cup. If the work is
reverse, those liquids cannot mixed together and have to waste them. When mixing those
resin and hardener, slowing and “M” shaped mixing is very useful to avoid the formation of
bubbles in the liquids. Mixing under the sun or in the curing room is very helpful since it can
increase the rate of mixing.
The samples are placed inside the small container cup. And those small container cups are
needed to be properly cleaned with WD40 and apply the release agents to inside the cup
before the casting process is done. Otherwise, the removing of those samples without the help
of release agents in the next days will be a very hard work because those mixed liquid sickly
attach to the inside faces of the small container. After mixing process of resin and hardener is
successfully done, those mixes are slowly pour to the small containers which the concrete
samples are placed inside. Pouring of those liquids can be stopped at the height of 12 mm of
the cup. After all of those process, the samples filled with resin and hardener mixed liquid

40
Maung Wai Hin Tun
inside the small cup are placed on the flat surface and rest them for 24 hours at 40°C to
perform the next step which is grinding and impregnation.
Figure 3.18: Samples after 24 Hours of Casting
Grinding is the second step to follow after casting step is successfully done. After 24 hours of
casting, the casted samples can be removed from the small container and wiped them with a
cleaned cloth. Cleaning of the small containers is necessary because the residual particles of
resin and hardener can be left in the interior face of those small containers. The samples can
be removed by removing the covers of the containers firstly and firmly push the samples out.
Using of hammer and wooden pieces are necessary if the student forgets to apply the release
agents to the interior faces of the small container and if it is very hard to take it out.
Grinding process can be done by using the polishing machine with the base plate of P240
abrasive plain paper which has the size of 10 inches or 254 mm in diameter. The annotation of
P240 is used because it has the grit of 240.

41
Maung Wai Hin Tun
Figure 3.19: Grinder/ Polisher for Nano-Indentation
The parameters are needed to set correctly with the designated applications. Speed for the
head rotator is about 30 or 50 and the speed for the base rotator is 120. The water has to be
turn on to apply the surface of the abrasive plain paper. And set the force to 10 N and put
down the head of Buehler polisher by pressing the two buttons on both sides with fingers to
lower down the head of the polisher to the abrasive plain paper. The specimens are placed
inside the rings of the grinder. Those rings can be easily remove and assemble them back.
Therefore, checking those rings are in the lock position is necessary before the specimens are
placed inside them. Otherwise, it can crush the specimens during the process of grinding if
those rings are not properly attached with lock. When everything is ready to start grinding,
press the green button on both sides simultaneously and the head rotator and the base rotator
are start to rotate inversely to each other. The basic theory of this process is to grind the resin
of the specimens from the head rotator by touching and rotating with the abrasive plain paper.
The process can be finished by pressing the two green buttons from the sides again until the
head rotator completely stop and raise back to its height. After getting the required dimension
of the specimen which is about 7mm in thickness, checking the thickness of the specimen can

42
Maung Wai Hin Tun
be done by using the measurement tool of Vernier Caliper. During the process of
measurement the thickness, only the sides of the specimens are needed to be measure and they
all have to be same. If one or two part is not as same as the other parts in the thickness,
manual grinding process is necessary in order to have the same thickness of that particular
specimen. Manual grinding process can be done by only turning on the base rotator and place
the portion or the part of the specimen facing down to the abrasive plain paper by pressing
firmly and apply some pressure to the specimen from the fingers. It is a very hard and careful
process. If the specimen is got loosen from hands because of the uncontrollable speed of the
base rotator, the specimen will jump to somewhere and can be end up crushing because of the
momentum. Also need to care not to apply pressure on one portion for too long. Otherwise,
the thickness of the specimen can be different from one portion to another portion.
If the specimens still need more time to get grinding, they have to be installed in the grinding
machine again and doing some grinding process again until they have required thickness. And
checking with Vernier Caliper measurement tool and manual grinding processes will be
applied again.
Figure 3.20: Manual Grinding Process

43
Maung Wai Hin Tun
Figure 3.21: Manual Checking of Sample Thickness by Using Vernier Caliper
When all the samples are relatively flat with the average thickness of 7 mm, the impregnation
process will follow. Epothin (Epoxy) resin and Epothin (Epoxy) hardener produced from
Buehler from United State of America are proportionally stirred and mixed inside a small cup
with small amount of red pigment until the formation of those two liquids become thoroughly
mixed with the red pigment and the color of the mix becomes clear red with no bubbles.
The amount required for those Epothin resin and hardener in ml are as followed table.
Table 3.3 4: EpoThin Resin and Hardener in ml
Number of
Samples
4 6 7 8 9 10
Epothin
Resin
15 20 25 30 35 40
Epothin
Hardener
6 8 10 12 14 16

44
Maung Wai Hin Tun
Figure 3.22: Bottle of EpoThin Epoxy Hardener
Figure 3.23: Bottle of EpoThin Epoxy Resin

45
Maung Wai Hin Tun
As same as the casting with the resin, the stirring and mixing process has to be very careful
when measuring the amount of those resin and hardener with the required amount of red
pigment because the impregnation of the samples will not be set in the next day if the required
proportion amounts of those are not accurate to the standard table. Also taking care of mixing
is needed to be very cautious because only resin can pour to the hardener cup because as
mentioned above, those liquids cannot mixed together and have to be wasted if the work is
reverse. And mixing slowly with “M” shape under the sun or in the concrete curing room will
again be applied to increase the rate of the mixing and also to avoid the formation of many
bubbles in the liquids.
The samples are again placed inside the small container cup and those small container cups
are needed to be properly cleaned with WD40 again and apply the release agents again to
inside the cup before the casting process is done. And those samples with the molding cups
are placed inside the vacuum chamber. There is a cup holder inside the vacuum chamber and
place a small cup on the holder and adjust the locations of the molding cups before pouring
the impregnation liquid mixes to them.
After mixing process of Epothin resin and Epothin hardener with red pigment is successfully
done, those mixes are slowly pour to the small cup which is held in the cup holder of the
vacuum chamber and slowly pouring those liquids mixes from the small cup to the molding
cups which the concrete samples are placed inside. Pouring of those liquids can be stopped
when it reaches the satisfactory level. After all of those processes, leave those samples in the
vacuum chamber and close the lid of vacuum chamber in order to pressurize to remove
entrapped air from epoxy. That vacuum chamber is evacuated by a waterjet pump prior to
impregnation. A vacuum chamber that is pumped down to 26 mbar and the epoxy is fed from
its cup outside the vacuum chamber to the top of the specimen from a plastic tube. After
resting the samples inside the vacuum chamber for 10 to 20 minutes, it can be depressurized
slowly and let the samples to rest inside the vacuum chamber for 24 hours before the next
process, polishing is introduced.

46
Maung Wai Hin Tun
Figure 3.24: Vacuum
Figure 3.25: impregnated Liquid Cup inside the Vacuum

47
Maung Wai Hin Tun
Figure 3.26: Pouring the Impregnated Liquid to the Samples inside the Vacuum
Same grinding process will be applied before the polishing process begins and after resting
the samples in the vacuum chamber for 24 hours. The impregnated samples can be removed
from the small container and wiped them with a cleaned cloth again as same as removing
from the casting process. Cleaning of the small containers is necessary because the residual
particles of resin and hardener from impregnation can be left in the interior face of those small
containers. The samples can be again removed by removing the covers of the containers
firstly and firmly push the samples out. Using of hammer and wooden pieces are necessary if
the student forgets to apply the release agents to the interior faces of the small container and if
it is very hard to take it out. The sample can obviously see with two layers which are the clear
layer of casted resin and red layer of impregnated resin.
Firstly, mark the back of the sample with the sign of “X” to make sure the marked side is
facing up when install them the grinding machine. Grinding process can be commenced with
the abrasive plain paper of P280. And all the same processes of checking the lock is engaged
in the head rotator, setting out the correct parameters of head and base rotator speeds, pressing
the side buttons simultaneously to start the grinding, checking the thickness with Vernier
Caliper and manual grinding will be applied as discussed above in impregnation process.

48
Maung Wai Hin Tun
The final grinding stage starts with changing the abrasive plain paper of P280 to P400 to grind
for only a minute. And mark the other the polishing side with square mark around the
concrete cube sample and proceed the grinding the square marked side again. And change the
abrasive plain paper to P800 with the remaining speeds and the force of 10N. And change the
abrasive plain paper again to P1200 and do the grinding again for about 5 minutes with the
same parameters. Extra care of not applying too much water in these final stages is needed
because the concrete surface is already partially exposed. When the square mark is noticed to
fade completely, stop the grinding process because it means the face of the concrete sample is
satisfactorily exposed for polishing.
Figure 3.27: Sample marked with Square Shaped around 4 Sides
After getting the satisfactory thickness of 7 mm, chambering the side of the specimen with
manual grinding is necessary in order to let the polishing liquids flow inside the face of the
specimen during performing the polishing process.
Polishing process can be initiated by setting the speed for the base rotator with 150, the speed
for the head rotator with 50 and the force of 10N. Water has to be completely turned off and
start the polishing process with placing 9 µm abrasive paper on the base rotator. And also turn
on the Burst Modular Dispensing System which is dropping a single drop of dispensing water
to abrasive paper continuously. Take 20 ml of 9 µm Meta Di Monocrystallinc Diamond

Project 462

Recommended

Recommended

More Related Content

Viewers also liked

Viewers also liked (20)

Similar to Project 462

Similar to Project 462 (20)

Project 462