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Running Head: ATOMIC FORCE MICROSCOPY

Atomic Force Microscopy
Institutional Affiliation
Date

1

ATOMIC FORCE MICROSCOPY

2

NANOINDENTATION ON CONCRETE SAMPLE AND SHALE USING ATOMIC
FORCE MICROSCOPY
CONTENTS
Chapter
C1

2.1.1

Content
Introduction
Concrete
Shale
Thesis
Literature Review
Concrete
Microstructure

2.2.2

C-S-H

2.2.3

Mechanical Properties In
Different Phases
Shale
Mechanical Characteristics

1.1
1.2
1.3
C2
2.1

2.2
2.2.1
C3

Body
3.1
3.1.1

Concrete
Contact Mechanisms

3.1.2

Nanoindentation

3.1.3

Atomic Force Microscopy
Sample Preparation

3.1.3.1
3.2

Shale
3.2.1
3.2.2

C4

Identification
Atomic Force Microscopy
Conclusion

4.1
4.2

Chapter 1: INTRODUCTION

Page

ATOMIC FORCE MICROSCOPY
1.1

3

Concrete cement materials are usually used In large scale during construction, but

fundamental mechanical characteristics such as strength, ductility, shrinkage and fracture
behaviors are usually effective in micro quantities. This research will involve classification of
nanoscale properties of concrete using mechanical classification.
A specific sample preparation will involve evaluation of microstructure and nanostructure
using atomic force microscopy technique. The study will analyze in depth concrete formation
using nonchemical properties of water to cement and micro nanochemical modifiers. Moreover,
the study will analyze the properties of interfacial transition zone in concrete despite its
complicated nature. The sole goal of this study will be develop new material with improved nano
mechanical properties and create a new knowledge about microscopic phenomena for multi-scale
modeling.
Nano technology offers an idea to create a more environmentally friendly material. Nano
structure of concrete is governed by features contained in the structure of calcium silicate hydrate
(C-S-H). This includes ductility, creep, shrinkage, fracture behavior and durability. Over years,
researchers have used different methods to relate mechanical properties to nano structure but the
research link relating to C-S-H is still unresolved. The goal of the research is to enable
microscopic properties from the nanoscale to modified substances with an immediate objective
of determining local mechanical properties like elasticity and hardness of the microstructure.
Nanoindentation has its origins since 1822 which developed the hardest concrete
microstructure capable of leaving a permanent mark on another material where one material with
known properties leaves intent to another with unknown properties. This method was also used
to determine nano properties of the interfacial transition zone in cement paste.

ATOMIC FORCE MICROSCOPY
1.2

Shale is a fine grained rock mainly composed of clay which majorly influences its

mechanical properties such as elasticity. Shale is rich organic material like kerosene useful in
production of hydrocarbons useful in formation of gas and oil in natural fractures caused by
tectonic forces. Today everybody is aware of the scale gas and its extensive use. Mechanical
properties of shale vary mineralogical hence toughness varies too; this makes shale unstable
hence no standard sample can be used for mechanical testing. Nano indentation provides an
alternative for providing needed mechanical properties. Thus, the purpose of this research is to
evaluate mechanical properties of shale.
Millions of shale wells are being drilled in the world without cracking; this has been
facilitated by mechanical studies of shale rocks of micro rocks around the core which are
millimeters in size. The studies will analyze applicability of nano- indentation of principal rock
contents which affect mineralogy, porosity and organic content.
Fracture mechanics explains how brittle materials resist cracking; the study of a fracture
is analyzed at a micro level using a high load with long cracks at the end. This technique is
limited to delicate environment with micro structures. The capability of making accurate and
repeatable measurements in an area makes nanoindentation system tool for fracture study on
small samples. Fracture toughness will be calculated using different equations depending on the
type of shale. Based on recent researches, nanoindentation evaluates fracture toughness of
interfaces similar to large scale testing. The traditional method was used to calculate toughness
using load displacement processes, hardness, radial crack lengths and elastic modulus.
The scope of the study has utilized nanoindentation system to measure elastic modulus
and hardness of shale as well as analyzing fracture toughness determinations using traditional

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ATOMIC FORCE MICROSCOPY

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crack measurement. This involves designing shale samples for nanoindentation tests and
different methods to analyze fracture toughness in different shale types.
1.3

Structure of thesis

Concrete
Chapter 2 analyzes the microstructure of concrete, usable C-S-H models, determination
of various methodologies to determine mechanical properties of different phases of concrete.
Chapter 3 forms the body of the study, establishes a detailed study of nanoindentation and atomic
force microscopy.
Shale
Chapter 2 the research justification and outline of several other methods used to measure
mechanical properties such as toughness as well as introduction to other shills in
nanoindentation.
Chapter 3: body describes the character and different types of shale based on experience
tests.

Chapter 2: LITERATURE REVIEW
2.1

CONCRETE

2.1.1 Microstructure

ATOMIC FORCE MICROSCOPY
Concrete is a heterogeneous mixture of mortar with an interfacial transition zone in
between the composite containing sand and cement paste. When cement is mixed with water, it
undergoes hydration reaction forming rigid structure heterogeneous in nature. The main phases
present influence the properties of cement logy material. These phases include; calcium silicate
hydrate, calcium hydroxide, Ettringite, Mono-sulfate, un-hydrated cements particles and air
voids.

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ATOMIC FORCE MICROSCOPY
2.2.2

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Calcium Silicate Hydrate (C-S-H)
This is the main phase that contributes to almost 70% of concrete volume and relates to

most microscopic characteristic. Previously, researchers applied experiments to characterize this
material. Le CHATELIER, 1887 described a gel like morphology of C-S-H phase. Taylor (29),
compared the atomic structure with many known crystalline calcium silicate hydrates suggesting
that it is similar to that of naturally existing minerals such as Jennite. Another suggestion states
that semi crystalline calcium silicate hydrate have an intermediate structure CaO2 of in between
the gel. The semi crystalline structures include C-S-H, C-S-H (I) and C-S-H (II). It has also been
discovered that C-S-H contains polymers, pantermers and octamers using magnetic nuclear
resonance. Other methods include scanning electron microscopy, XRAY mapping and the latest
atomic force microscopy that indicated a crystalline nature of C-S-H using a small angle neutron
revealing also two types of C-S-H. Therefore, the goal here is to come up with a description of
morphology and create a relationship between microstructure and microscopic properties.
According to the information available from researches, different models of the phase were
derived; the first model was developed by Taylor who performed different volumetric
proportions present in cement materials in a solid phase. (Powers and Brown yard formulas)
Vcs = 0:20(1 - p) ٤
Vcp = p- 1:32(1 - p)٤
Vcs = 2:12(1- p)٤
Vcl = (1 - p)(1 - ) ٤

chemical shrinkage
capillary

pores

gel

pores

unhydrated cement

Where;
p- Initial porosity (space initially occupied by water)

ATOMIC FORCE MICROSCOPY

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٤- degree of hydration

P=

w/c
W/c +pw/pc
Where;
Pc (cement mass density) = 3150 kg=m3
Pw (water mass density) = 1000 kg=m3.

This model concentrates the whole phase but does not distinguish between the two layers
of C-S-H nor incorporating any other hydration product. This was criticized by several scientists
including Brun...