copyright 2018, lochana poudyal

Use of Nanotechnology in Concrete

by

Lochana Poudyal, B.E.

A Thesis

In

Civil Engineering

Submitted to the Graduate Faculty

of Texas Tech University in

Partial Fulfillment of

the Requirements for

the Degree of

MASTER OF SCIENCES

Approved

Moon Won, Ph.D., P.E.

Chair of Committee

Priyantha W. Jayawickrama, Ph.D.

Mark Sheridan, Ph.D.

Dean of the Graduate School

May, 2018

Texas Tech University, Lochana Poudyal, May 2018

ii

ACKNOWLEDGMENTS

I express my gratitude to my advisor and committee chair, Dr. Moon Won for his support

and guidance on this thesis and throughout my graduate studies at Texas Tech University.

I thank Dr. Priyantha W. Jayawickrama for his help and guidance on this research project

and throughout my graduate studies.

I also thank my family, friends and colleagues who supported me in numerous ways.


iii

TABLE OF CONTENTS

ACKNOWLEDGMENTS .................................................................................................. ii

ABSTRACT ...................................................................................................................... vii

LIST OF FIGURES ......................................................................................................... viii

LIST OF TABLES .............................................................................................................. x

LIST OF ABBREVIATIONS ........................................................................................... xii

I. INTRODUCTION ........................................................................................................... 1

Objective of research ....................................................................................................... 4

Research Context............................................................................................................. 5

Production of ordinary Portland cement ......................................................................... 6

Grinding and blending ..................................................................................................6

Burning – cement clinker formation .............................................................................7

Formation of cement .....................................................................................................9

Type I ......................................................................................................................11

Type II ......................................................................................................................12

Type III ......................................................................................................................12

Type IV ......................................................................................................................12

Type V ......................................................................................................................13

White cement ..............................................................................................................13

Hydrophobic cement ...................................................................................................13

Blended cement ..........................................................................................................13


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Air-entraining cement .................................................................................................13

High alumina cement ..................................................................................................14

Overview of thesis ......................................................................................................... 15

II. LITERATURE REVIEW ............................................................................................. 17

Supplementary cementitious materials (SCMs) ............................................................ 17

Fly Ash ......................................................................................................................18

GGBFS ......................................................................................................................24

Rice Husk Ash (RHA) ................................................................................................27

Pumice ......................................................................................................................28

Silica Fume .................................................................................................................29

Metakaolin ..................................................................................................................30

Sewage sludge ash ......................................................................................................32

Nano Concrete ............................................................................................................... 33

Nano Calcium carbonate ............................................................................................... 34

III. MATERIALS .............................................................................................................. 37

Coarse Aggregate .......................................................................................................... 37

Fine Aggregate .............................................................................................................. 37

Fly Ash .......................................................................................................................... 38

Ordinary Portland cement ............................................................................................. 38


v

Nano Calcium Carbonate .............................................................................................. 39

IV. METHODS ................................................................................................................. 40

Properties of coarse aggregate....................................................................................... 40

Absorption and specific gravity of coarse aggregate ..................................................40

Absorption and specific gravity of fine aggregate ......................................................41

Moisture content for coarse and fine aggregate ..........................................................42

Sieve analysis for coarse and fine aggregate ..............................................................42

Tests conducted on fresh concrete ................................................................................ 42

Workability .................................................................................................................43

Setting time .................................................................................................................43

Heat of hydration ........................................................................................................44

Tests conducted on hardened concrete .......................................................................... 44

Compressive strength .................................................................................................44

Modulus of elasticity ..................................................................................................45

Shrinkage Ring test .....................................................................................................45

Design matrix ................................................................................................................ 46

V. RESULTS .................................................................................................................... 48

Workability.................................................................................................................... 48

Setting test ..................................................................................................................... 49


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Heat of hydration ........................................................................................................... 52

Compressive strength .................................................................................................... 54

Elastic modulus ............................................................................................................. 57

Shrinkage Ring Test ...................................................................................................... 60

VI. DISCUSSIONS........................................................................................................... 62

VII. SUMMARY & RECOMMENDATIONS................................................................. 64

REFERENCES ................................................................................................................. 66

APPENDIX ....................................................................................................................... 68


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ABSTRACT

Nanoparticles infused concrete also known as nano concrete has been an

unindustrialized area of research that is yet to be commercialized. These exorbitant

materials are still in progress of having their prices reduced through different sustainable

production to get their way into the concrete industry as sustainable, durable and

economical material. In contrast, nano CaCO3, a widely used material in pharmaceutical

and different other industry, is one of the cheapest nanomaterials that could be used in

construction industry. This study consists of preliminary analysis to understand the

behavior of concrete infused with nano CaCO3. Ordinary concrete and fly ash concrete was

mixed with 1% and 3% nano calcium carbonate. Workability, setting time and calorimeter

test were conducted to understand the change in the behavior of fresh concrete. Similarly,

compressive strength, elastic modulus and shrinkage ring test were conducted on hardened

concrete. Results indicated an enormous increase in the rate of hydration and early strength

after addition of nano CaCO3. However, a decrease in heat of hydration and elastic modulus

was observed with the addition of nano calcium carbonate. This unique property makes

nano concrete more crack resistant which was observed through shrinkage ring test.


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LIST OF FIGURES

1.1 The relative size of materials used in the construction industry (SOBOLEV, 2016).

................................................................................................................................... 1

1.2 Strength assessment of concrete with nano SiO2 (Hanus, 2008). ............................. 3

1.3 Rate of hydration of different compounds in concrete (won). ................................ 11

2.1 Left to Right: Class C fly ash, Metakaolin, Silica fume, Class F fly ash, Slag,

Calcined shale. (THE CONCRETE COUNTERTOP INSTITUTE, n.d.). .............. 17

2.2 Typical class C Fly ash (Alibaba, n.d.). ................................................................... 18

2.3 Morphology of Fly ash (Won, 2016)........................................................................ 20

2.4 Typical GGBFS used in construction industry (Alibaba, n.d.). ............................... 25

2.5 Morphology of GGBFS under SEM (Janardhanan, 2015). ..................................... 26

2.6 Several stages of Rice Husk Ash (Thomas, 2018). .................................................. 27

2.7 Typical volcanic ash (Geology, n.d.). ...................................................................... 28

2.8 Morphology of Silica Fume under SEM (Pittsburgh Mineral and Environmental

Technology, Inc, n.d.). ............................................................................................. 30

2.9 Morphology of Metakaolin under SEM (Hindawi, n.d.). ........................................ 31

2.10 Schematic figure to produce nano calcium carbonate (Eda Ulkeryildiz, 2016). ..... 35

2.11 Varied sizes of nano calcium carbonate (Gupta, 2004). .......................................... 36

5.1 Slump for different samples. .................................................................................... 49

5.2 Penetration resistance for ordinary concrete, and 1% and 3% nano

replacement in ordinary concrete ............................................................................ 50

5.3 Penetration resistance for F35, and 1% and 3% replacement

of nano in F35 .......................................................................................................... 51

5.4 Penetration resistance for F45, and 1% and 3% replacement

of nano in F45 .......................................................................................................... 51

5.5 Setting time for all samples...................................................................................... 52

5.6 Heat of hydration for samples 0 – 0, 3 – 0, 3 - 35 ................................................... 53

5.7 Heat of hydration for samples 0 – 0, 1 – 0, 1 - 45 ................................................... 54

5.8 Compressive strength for samples 0 – 0, 1 – 0, 3 - 0 ............................................... 55

5.9 Compressive strength for samples 0 – 35, 1 – 35, 3 – 35 ........................................ 56


ix

5.10 Compressive strength for samples 0 – 45, 1 – 45, 3 - 45 ......................................... 56

5.11 Compressive strength for all samples ...................................................................... 57

5.12 Elastic modulus for samples 0 – 0, 1 – 0, 3 - 0 ........................................................ 58

5.13 Elastic modulus for samples 0 – 35, 1 – 35, 3 - 35 .................................................. 59

5.14 Elastic modulus for samples 0 – 45, 1 – 45, 3 - 45 .................................................. 59

5.15 Elastic modulus for all samples ............................................................................... 60

A 1 Gradation of coarse aggregates used. ...................................................................... 68

A 2 Gradation of fine aggregates. .................................................................................. 69

A 3 Slump test conducted for fresh concrete. ................................................................ 79

A 4 Preparation of sample for setting time. ................................................................... 79

A 5 Compressive strength Testing machine. ................................................................. 80

A 6 Concrete mold after removal of outer ring for shrinkage ring test. ........................ 80

A 7 Data logger used for shrinkage ring test. ................................................................ 81

A 8 Compaction of sample in the plastic mold for compressive strength

and elastic modulus. ................................................................................................ 81

A 9 Elastic modulus Test. .............................................................................................. 82

A 10 Semi-adiabatic calorimeter used for determining heat of hydration on

fresh concrete. ..................................... ................................................................... 82


x

LIST OF TABLES

1.1 Mineral composition of ordinary Portland cement ................................................... 6

1.2 Typical output from the kiln ..................................................................................... 9

1.3 Categories of several types of cement .................................................................... 11

2.1 Materials price sourced from Alibaba and eBay website ........................................ 34

3.1 Properties of Coarse Aggregate ............................................................................... 37

3.2 Properties of fine aggregate ..................................................................................... 38

3.3 Composition of Fly ash ............................................................................................ 38

3.4 Composition of nano CaCO3 ................................................................................... 39

4.1 Design matrix ........................................................................................................... 40

4.2 Different notation used to differentiate samples. ..................................................... 47

A 1 Sieve Analysis of coarse aggregates ........................................................................ 68

A 2 Sieve Analysis of fine aggregates ............................................................................ 69

A 3 Mix design for all the samples ................................................................................. 70

A 4 Setting time data for sample 0-0 .............................................................................. 70



A 7 Setting time data for sample 0-35 ............................................................................ 71



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A 13 Compressive strength for all samples for 1 day ....................................................... 74

A 14 Compressive strength for all samples for 3 days ..................................................... 75

A 15 Compressive strength for all samples for 7 days ..................................................... 75

A 16 Compressive strength for all samples for 28 days ................................................... 76

A 17 Elastic modulus frequency for all samples for 1 day ............................................... 76

A 18 Elastic modulus frequency for all samples for 3 days ............................................. 77

A 19 Elastic modulus frequency for all samples for 7 days ............................................. 77

A 20 Elastic modulus frequency for all samples for 28 days ........................................... 78


xii

LIST OF ABBREVIATIONS

F35 – Concrete with 35% Fly ash by mass of cement

F45 – Concrete with 45% Fly ash by mass of cement

SCMs – Supplementary Cementitious Materials

HVFA – High Volume Fly ash


1

CHAPTER I

INTRODUCTION

Nanoparticles have been widely used in different fields including but not limited to

medical industry, pharmaceutical, and construction. Use of nanoparticles in concrete is one

of the few emerging topics. Nano TiO2, nano SiO2, nano Al2O3, nano Fe3O4, nano ZrO2,

carbon nanotubes and carbon nanofibers are most commonly used nanoparticles in the field

of research (Hanus, 2008). These particles have shown a phenomenal effect in the

hydration of concrete through a nucleation process. They act as a seed for the hydration of

calcium silicate hydrate. Higher the rate of hydration, earlier is the strength gain in

concrete. Same materials behave differently with the decrease in the size of particles. For

instance, rice husk ash and nano SiO2 are same siliceous material. However, the behavior

of these materials in concrete is very different. Figure 1.1 provides us an idea about the

distribution of different material size used in construction industry.

Figure 1.1 The relative size of materials used in the construction industry (SOBOLEV, 2016)

Incorporating nanoparticle in concrete offers many advantages including ultra-high

compressive strength, high split tensile strength and ductility, high aggregate paste


2

bonding, and higher thermal durability – thus can be used in refractory concrete

(SOBOLEV, 2016). It also offers anti-microbial surfaces, which would be ideal for

hospitals, health care center and nursing center (Hanus, 2008). These materials also

increase the durability of high traffic rigid pavement, as it offers higher resistance to

thermal shock and abrasion. Moreover, nano TiO2 has also been used for coating of steel

reinforcement as it offers better corrosion resistance (Hanus, 2008). Thus, the use of

nanoparticles in concrete has enhanced the efficiency and performance of ordinary

concrete.

Industrial waste products such as Fly Ash, GGBFS, sludge sewages are widely used

as they make concrete more sustainable, workable, finish able, and mainly increases the

later age strength. In contrast, it reduces the early strength of concrete significantly. The

dosage of these supplementary cementitious material (SCMs) has been limited due to a

decrease in early strength. However, the addition of nano SiO2 to SCM modified concrete

has helped in improving the early compressive strength, split tensile strength, flexural

strength, permeability, abrasion resistance, due to increase in the rate of pozzolanic reaction

(Hanus, 2008). Nano SiO2 is produced from agricultural waste Rice Husk Ash (RHA) and

helps in improving the durability, sustainability, and performance of concrete (Ehsani,

2016). Figure 1.2 shows the increase in early strength of concrete with the addition of nano

SiO2.


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Figure 1.2 Strength assessment of concrete with nano SiO2 (Hanus, 2008).

Moreover, the addition of carbon nanotubes (CNTs) and carbon nanofibers (CNFs)

also compensates the loss of early strength due to the addition of Fly Ash, mainly the tensile

strength. The tensile strength and Young's modulus of CNTs are 100 times higher than the

steel, however weight per volume ratio is extremely lower than the steel (Hanus, 2008).

Thus, these properties could help in producing concrete with higher tensile strength without

the use of steel reinforcement.

However, as much as these nanoparticles have an excellent effect on the properties

of concrete, they are not used as much commercially, due to rare availability and the high

price of these materials. In fact, CNTs and CNFs are not even manufactured commercially

in large scale (Hanus, 2008). Researchers are trying to improve the manufacturing

technology to produce nanoparticles in large scale so that they would be readily available

at reasonable price.

Nano CaCO3, on the other hand, is used in the various technical field such as medical

industry, and pharmaceuticals. Due to its wide application, nano CaCO3 is relatively


4

produced in a rather large scale as compared to other nano-materials. In addition, it is

cheaper than the ordinary Portland cement. This report describes the experiments

conducted to evaluate the modifications to concrete properties affected by the inclusion of

nano CaCO3.

Objective of research

There has been various work done to improve the properties of concrete, especially to

make it more sustainable and efficient at the same time. As concrete is one of the main

sources to release CO2 in the air, any efforts to reduce the amount of cement needed to

produce concrete without compromising concrete properties would be beneficial. Use of

industrial and agricultural waste such as Fly Ash, GGBFS, sewage sludge, RHA etc. has

helped in a certain amount to meet the criteria of sustainable and durable concrete,

however, the use of those materials also reduces the early strength of concrete due to slow

hydration. Modern technology such as incorporating nanoparticles in concrete, which are

thousands of times smaller than cement, could help in increase in the rate of hydration and

filling the nanopores, making concrete more durable and crack resistant. Some

nanoparticles have also shown to increase the tensile strength of concrete without the use

of steel reinforcement. Thus, there has been an increased interest in using these

nanoparticles to make high efficient and smart concrete. If more research is conducted in

this area, concrete with higher sustainability, durability and higher performance could be

achieved for a new generation. The objective of this research was to investigate the

modifications to concrete properties, especially early age strength, of concrete containing

fly ash if certain amount of cement is replaced with nano CaCO3. In this report, use of nano

CaCO3 in concrete has been tested in both fresh and hardened concrete. Material properties

evaluated for fresh concrete are:

✓ Workability

✓ Setting time

Those evaluated for hardened concrete are:

✓ Compressive strength


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✓ Modulus of elasticity

✓ Permeability

✓ Cracking potential

Thus, this thesis includes a detailed analysis of change in fresh and hardened concrete

properties after the addition of nano CaCO3.

Research Context

To fully understand the research problem, one must have a fair knowledge of the

production of concrete, its compositions, applications, and limitations that have been faced

in the construction industry till date.

Concrete is a composite material that consists of cement, coarse aggregates, fine

aggregates, water, and admixture. Concrete is one of the main building materials used in

construction industry. Concrete is very high in compression, but very low in tension, thus

reinforcements are used to compensate the tensile strength, making it a suitable building

material for every construction. Despite its wide applicability, it is also one of the main

materials that produce high greenhouse gases during production; 8% of the total CO2

emission is from cement production.

Ordinary Portland cement consists of four main oxides: Calcium oxide (CaO),

Silicon dioxide (SiO2), Sulphur trioxide (SO3) aluminum trioxide (Al2O3), and ferric oxide

(Fe2O3). Similarly, the mineral composition of different solids present in the cement is

summarized in the Table 1.1.


6

Table 1.1 Mineral composition of ordinary Portland cement.

Mineral

name

Cement

notation

Oxide formula Chemical

formula

Chemical name

Alite C3S 3CaO.SiO2 Ca3SiO5 Tricalcium

Silicate

Belite C2S 2CaO.SiO2 Ca2SiO4 Dicalcium

Silicate

Aluminate C3A 3CaO.Al2O3 Ca3Al2O6 Tricalcium

Aluminate

Ferrite C4AF 4CaO.Al2O3.Fe2O3 Ca2AlFeO5 Tetracalcium

Aluminoferrite

Portlandite CH CaO.H2O Ca(OH)2 Calcium

hydroxide

Gypsum CSH2 CaO.SO3.2H2O CaSO4.2H2O Calcium sulfate

dihydrate

Lime C CaO CaO Calcium oxide

Production of ordinary Portland cement

Ordinary Portland cement is manufactured in the cement plant. Limestone, sand,

clay, and iron ores are the common raw materials needed, which are then ground and burnt

to make cement clinkers. Finally, the cement clinkers are finely grounded in the kiln at

elevated temperature to produce cement. The step by step process for the manufacture of

cement is discussed in detailed below (The science of concrete, n.d.).

Grinding and blending

Prior to sending the raw materials into the kiln, they are ground and blended

together using either dry process or wet process (The science of concrete, n.d.). The water


7

facilitates the grinding process but then the water needs to be removed before the materials

are entered the kiln, thus consumes more energy and time. The wet process is now almost

obsolete as most of the manufacturing plant uses a high efficient grinding machine that

facilitates dry grinding (The science of concrete, n.d.).

Burning – cement clinker formation

The blended materials are then burnt down in a different process to form cement

clinkers. Variety of fuels such as coal, natural gas, fuel oil, lignite etc. are used to burn the

kiln at the bottom (The science of concrete, n.d.). This process requires the maximum

temperature and energy. The raw materials are brought at the upper end of the kiln and are

entered where the materials move to the bottom and are slowly rotated and moved forward

such that enough time is allowed for each reaction to be completed at appropriate

temperatures (The science of concrete, n.d.). In this process, there are different reaction

zones that are again furthered discussed in detail below.

Dehydration zone (up to 450oC)

The blended raw mixtures are dehydrated in this zone to make the materials

completely free from moisture. This process is mandatory even the grinding is done

through the dry process to remove adsorbed moisture.

Calcination zone (450oC – 900oC)

In this zone, the dehydrated mix is burnt at a higher temperature to make oxides out

of solid materials (The science of concrete, n.d.). At the end of this zone, the kiln consists

of all four oxides Calcium oxide (CaO), Silicon dioxide (SiO2), Sulphur trioxide (SO3)

aluminum trioxide (Al2O3), and ferric oxide (Fe2O3), which are then ready to undergo

further reaction (The science of concrete, n.d.). Calcination refers to decomposing of solid

material.


8

Solid state reaction zone (900oC – 1300oC)

In this zone, the reaction starts in the solid state to form Dicalcium silicate (C2S),

one of the main mineral ingredients in cement (The science of concrete, n.d.). The reactive

silica and calcium oxide combine to form blite (C2S). Also, calcium aluminates (C3A) and

calcium ferrites (C4AF) are formed in this zone which is later used in a clinkering zone to

reduce the temperature for the formation of tricalcium silicate (C3S). The calcium

aluminates and ferrites melt at a lower temperature (~1300oC) and help in a faster rate of

reaction in the clinkering zone to reduce the temperature. Following different reactions

undergo at this stage to form different minerals.

2CaO + SiO2 CaO.SiO2 (C2S)

3CaO + SiO2 3CaO.SiO2 (C3S)

3CaO + Al2O3 CaO.Al2O3 (C2A)

4CaO + Al2O3 + Fe2O3 4CaO.Al2O3.Fe2O3 (C4AF)

Clinkering zone (1300oC – 1500oC)

This is the hottest zone where tricalcium silicates (C3S) are formed, one of the main

components responsible for the strength of the concrete. At first, C3A and C4AF melt which

causes to mix to agglomerate into big nodules bound by a thin layer of liquid (The science

of concrete, n.d.). Inside this liquid, C2S crystals react with CaO to form C3S. Thus, the

crystals of C3S grow inside the liquid while the number of C2S decreases (The science of

concrete, n.d.). This zone is completed when all the amount of silica is converted into C3S

and C2S and amount of CaO is reduced to <1% (The science of concrete, n.d.). Finally,

cement clinkers are formed which consists of all cement minerals but in the solid state.


9

Cooling zone

The clinkers are cooled rapidly either by blow drying or using water to avoid the

decomposition of C3S back into C2S and CaO and to have a more reactive cement.

Formation of cement

In this process, the cement clinkers are now ground into a fine powder to form

Portland cement. Gypsum (CSH2) is added in this process to avoid the flash set of cement

due to the presence calcium aluminates and ferrites (The science of concrete, n.d.). At this

stage, the manufacture of cement is complete and is ready to be bagged and transported.

The typical kiln output consists of following main mineral components:

Table 1.2 Typical output from the kiln.

Cement

compound

Output

C3S 49%

C2S 25%

C3A 12%

C4AF 8%

Each of the cement minerals has their own contribution to make the cement better

and efficient. Some contribute at the production plant, while some contribute during the

hydration of cement. The properties of different mineral present in cement are discussed in

the section below.

Tricalcium silicate (C3S)

They are one of the main components that contribute to the strength of cement paste

due to the formation of calcium silicate hydrate. C3S, also known as alite, comprises half

of the cement composition. Reactions involved in hydration of C3S is shown below.

2C3S + 6H 3CaO.2SiO2.3H2O + 3CH


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Dicalcium silicate (C2S)

They comprise about a quarter of the cement composition and is not as reactive as

alite. But, C2S contributes to the later age strength of cement paste. Hydration of C2S is

explained below with reactions.

2C2S + 4H 3CaO.2SiO2.3H2O + CH

Tricalcium aluminates (C3A)

This mineral comprises roughly 12% of cement composite and is the fastest

reacting mineral which causes a flash set of the cement paste. Thus, gypsum is added to

delay the hydration of C3A. These minerals contribute little to no strength gain of the

cement paste. However, they contribute to reducing the temperature by (~1000oC) of a

cement kiln in a production plant in the clinkering zone, in the formation of the elite.

Hydration of tricalcium aluminates is explained by following reactions.

C3A + 3CSH2 + 26H C6AS3H32 (ettringite)

C6AS3H32 + 2C3A + 22H 3C4ASH18 (Monosulfate)

Tetracalcium aluminoferrite (C4AF)

This compound also has the same contribution as that of tricalcium aluminates and

do not contribute to the strength of cement paste. They are used as fluxing agents to reduce

the temperature in a concrete plant in the clinkering zone. Hydration of tetracalcium

aluminoferrite is explained by following reactions.

C4AF + 3CSH2 + 26H C6AS3H32 (ettringite)

C6AS3H32 + 2C3A + 22H 3C4ASH18 (Monosulfate)

Figure 1.3 shows the contribution of different cement compounds to the strength of

concrete at different ages.


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Figure 1.3 Rate of hydration of different compounds in concrete (Won, 2016).

Depending on the percentage composition of different cement compounds, the

cement produced in concrete plant differs. These are used for different application

purposes. ASTM has classified cement into five various categories depending on the C3S

and C3A content. Different types of cement according to ASTM is given in Table 1.3.

Table 1.3 Categories of several types of cement.

Cement Types C3A content C3S content

Type I - Fairly high

Type II <8% Fairly high

Type III - High

Type IV Low Low

Type V <5% Fairly high

Type I

They are ordinary Portland cement used for the general purpose: buildings, precast

unit, pavements etc. C3S content is fairly high to increase the early strength.


12

Type II

It has low C3A content for moderate sulfate resistant concrete. Type I/II cement is

also available that meets the requirement for both type of cement, i.e., it has fairly high

early strength and is also sulfate resistant. Sulfate attack is a genuine issue in concrete.

Sulfate ions react with C3A to form ettringite and increase the volume of concrete causing

it to expand and crack.

Na2SO4 + Ca(OH)2 + 2H2O CaSO42H2O + 2NaOH

MgSO4 + Ca(OH)2 + 2H2O CaSO42H2O + Mg(OH)2

C3A + 3CaSO42H2O + 26H C6AS3H32 (ettringite)

Type III

This type of cement is used for an application that needs high early strength. C3S is

ground more finely and is high in amount compared to other types of cement, to increase

the rate of hydration. It is used mainly for quick repairs of infrastructure, rapid pace of

construction to bear loads sooner, and in precast plants to remove the form quicker.

However, short workability, the greater heat of hydration and lower ultimate strength limits

the use of this type of cement.

Type IV

This type of cement is also known as slow reacting cement, as the amount of C3S

is reduced significantly. This type of cement was produced after problems related to the

high heat of hydration was an issue when Type III cement was used. This type of cement

is used in big structures like dams and bridges to reduce the core temperature of concrete,

thus decreasing the early age cracking and increasing ultimate strength of concrete. Low

C3A content is also another advantage for sulfate prone places.


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Type V

Construction places prone to high sulfate attack uses this type of cement, as it has

the lowest amount of C3A content (<5%). The early age strength is like that of Type I or

Type I/II cement.

Other types of cement produced that are customized for different application are:

White cement

This is used for decoration purposes to give artistic look to the infrastructure. The

white color is attained by reducing the iron and magnesium content that gives cement grey

color. The strength and other properties are like that of Type I cement.

Hydrophobic cement

Water infrastructures like dams and bridges use this type of cement, where the

cement surface is hydrophobic, i.e., it repels water making it water resistant concrete. It is

also used in places where monsoon season is dominant, and cement cannot be stored for

longer time.

Blended cement

Cement is replaced (~65% by wt.) during the grinding of cement clinker with

GGBFS to produce blended cement. This has similar properties to that of Type III cement,

thus Type III cement is produced rarely. This is also the sustainable type of cement as it is

utilizing industrial waste produce cement.

Air-entraining cement

Air entraining agent is used in places that face the problem of freeze and thaw

periodically. Entrained air helps to escape the water present inside the concrete during

freezing weather to reduce the expansion of concrete. Similarly, the water is released back

to concrete during hot weather. This type of cement is produced using air entraining agent


14

such as resins, glues, sodium salts of sulfate with Ordinary Portland cement (The science

of concrete, n.d.).

High alumina cement

Very high compressive strength is the special feature of this type of cement. Bauxite

(aluminum ore) is ground together with cement to produce high alumina cement. This can

be especially used in infrastructure where fast repair is needed such as pavement to avoid

long traffic obstruction. Also, can be used in the prestressed concrete plant to remove the

formwork quickly.

However, as much as concrete has so many advantages in the field of construction

industry, it also has some serious limitations. The contribution of greenhouse gases like

CO2 and NOx from concrete industry is more than 8% in total and is expected to grow in

2050, as the demand will be more than double. This is a significant issue that needs to be

addressed as quickly as possible. Our earth’s climate is degrading day by day and has

already reached the irreversible stage, thus the only way would be to stop it from getting

worse than it already is.

Researchers have been going for years for an alternative to cement, to make the

construction industry more sustainable. Use of industrial waste such as: Fly ash, silica

fume, sewage sludge, GGBFS and agricultural waste such as: Rice husk ash, Palm oil fuel

ash, Bagasse ash, wood waste ash, bamboo leaf ash, and corn cob ash has been partially

replacing cement to improve its properties and making it more durable and sustainable.

Modern technologies have grown every day to save our environment and we must continue

to do this until we achieve our goal.

Use of industrial and agricultural waste to partially replace cement has been an

effective way to make concrete more sustainable, but this replacement reduces the early

strength of concrete. And again, many research has been going on to compensate the early

strength of concrete when these industrial wastes such as Fly ash and GGBFS are used.


15

Use of silica fume and metakaolin has been able to compensate some strength factors such

as abrasion resistance and increase in microhardness at an early age.

Similarly, this thesis is also a small effort towards more sustainable and durable

concrete and incorporating nanotechnology in concrete has helped to do so. Nano CaCO3

used in this project not helps to compensate the strength loss due to the addition of fly ash

but also helps in consuming more CO2. 98% pure CO2 is passed through liquid calcium

hydroxide to make precipitated calcium carbonate whose size could range from micro and

nano of a meter. Thus, this idea could be incorporated in utilizing the CO2 produced during

cement manufacture and pour the same nano CaCO3 in the clinkering zone to make a new

type of cement, that would be more sustainable and durable than the ordinary cement.

Overview of thesis

This thesis is divided into seven main chapters that have its own objective in

addressing the specific part of research that was conducted.

Chapter 1 includes the abstract of the research that provides a summary of the

research that was done and some critique results that were observed. This chapter also gives

an idea of the objective of research that includes the manufacturing process of cement and

different type of cement that has been produced for a different application.

Chapter 2 articulates the background of research done in the area of nanoparticles

and supplementary cementitious materials used in construction industry till date.

Chapter 3 provides the research overview that has been done in this field till date.

This chapter also includes the limitations and advantages of the all the materials that have

been used to improve the performance and sustainability of concrete.

Chapter 4 has the specifications and properties of all the materials that have been

used including the mill certificate for the Portland cement and Fly ash used, the gradation

of coarse and fine aggregates and the specification of nano CaCO3 used.


16

Chapter 5 includes all the specification of test including the step by step procedure

used to conduct a test on fresh and hardened concrete.

Chapter 6 consists of all the test results which are tabulated and plotted for better

understanding. This chapter also discusses the test results giving us an idea about the

efficiency of this research.

Chapter 7 includes the summary of research including some outstanding results that

were produced during the experimental investigation of our project.


17

CHAPTER II

LITERATURE REVIEW

This section comprises a summary of research studies done in the field of concrete

materials including supplementary cementitious materials and use of nanotechnology in

concrete.

Supplementary cementitious materials (SCMs)

Supplementary cementitious materials (SCMs) are used along with Portland cement

to improve and change the properties of concrete as suited with different applications. They

are either hydraulic or pozzolanic materials.

Figure 2.1 Left to Right: Class C fly ash, Metakaolin, Silica fume, Class F fly ash, Slag, Calcined shale. (THE

CONCRETE COUNTERTOP INSTITUTE, n.d.).

Hydraulic materials are material that, in finely divided form and in the presence of

moisture react with water to form cementitious material. GGBFS blended Portland cement,

calcium aluminate cement, are some of the examples of hydraulic cementitious material.

The pozzolanic material is siliceous or alumino-siliceous material that, in finely divided

form and in the presence of moisture chemically reacts with calcium hydroxide released

by the hydration of Portland cement to form compound possessing cementitious properties.

Fly ash, silica fume, metakaolin, rice husk ash, etc. shows pozzolanic properties.

C3S + H CSH + CH


18

CH + Pozzolan(S) CSH (calcium silicate hydrate)

Hydraulic materials react faster than pozzolanic materials, as pozzolanic materials

would have to wait for cement hydration to produce calcium hydroxide. Presence of

calcium hydroxide reduces the concrete strength. Thus, use of pozzolanic materials would

help to increase the later age strength of concrete by utilizing calcium hydroxide present in

the concrete. However, hydraulic materials provide higher early age strength as the rate of

hydration would be faster than in ordinary concrete but, these materials would not help

much for later age strength of concrete.

Some of the widely used Supplementary cementitious materials are discussed in the

section below:

Fly Ash

Fly ash is used as supplementary cementitious material to replace cement in the

production of concrete. Although the use of Fly ash was initiated in the early 19’s, however,

significant utilization started during mid 19’s (FHWA, 2016).

Figure 2.2 Typical class C Fly ash (Alibaba, n.d.).

Fly ash is a byproduct of burning pulverized coal or bituminous coal in an electrical

generating station. Moreover, it is the unburned residue that is carried away from the


19

burning zone in the boiler by flue gases and then collected by either mechanical or

electrostatic separators (FHWA, 2016). It is finely divided amorphous aluminosilicate with

varying amounts of calcium. The performance of fly ash concrete depends on physical,

mineralogical, and chemical properties of fly ash. The mineralogical and chemical

composition depends on the composition of coal, its sources and collection methods. The

calcium content is probably the best indicator of how concrete will behave with the addition

of fly ash. Depending on the amount of calcium content, fly ash is divided into two

categories: Class “C” and Class “F” Fly ash. Both have their own advantage and

limitations.

ASTM specification for Fly Ash

Class “F” Fly ash: Fly ash normally produced from burning anthracite or

bituminous coal that meets the applicable requirements for this class as given herein. SiO2

+ Al2O3 + Fe2O3 ≥ 70%. This class of fly ash has pozzolanic properties.

Class “C” Fly ash: Fly ash normally produced from lignite or sub-bituminous coal

that meets the applicable requirements for this class as given herein. SiO2 + Al2O3 + Fe2O3

≥ 50%. This class of fly ash, in addition, to having pozzolanic properties, also has some

cementitious properties as calcium content is higher.

The other limit placed on the composition of fly ash by ASTM is maximum

allowable loss-on-ignition (LOI), which indicates the presence of unburnt carbon. The limit

in ASTM is 6% for class F and class C fly ash, however, the specification allows class F

fly ashes up to 12% LOI (FHWA, 2016). Higher the amount of unburnt carbon, higher will

be the need of air entraining agent, as the carbon adsorbs the entrained air making it

unavailable to stabilize air bubbles.


20

Effect of fly ash on the properties of fresh concrete:

Workability

Increase in the workability of concrete even with low w/c ratio is one of the key

property improved with the use of high-quality fly ash. This is due to the morphology of

fly ash; the perfect spherical shape of this particle improves the workability by the ball-

bearing effect. Figure 2.3 shows the morphology of fly ash. Thus, a well-proportioned fly

ash concrete will have improved workability when compared with ordinary concrete of the

same slump. This means that, in a given slump, fly ash consolidates and flows better than

a conventional concrete.

Figure 2.3 Morphology of Fly ash (Won, 2016).

Bleeding

Fly ash reduces the amount and rate of bleeding as the water demand is reduced

due to improved workability. Amount of bleeding in the freshly placed concrete increases

the risk of plastic shrinkage reducing the durability of infrastructures. Increase in


21

workability facilitates in reducing water-cement ratio, thus reducing the overall water

content in the concrete which in turn decreases the amount of bleed water.

Air entrainment

Air entraining agent is essential to protect concrete from freeze and thaw. Entrained

air helps in reduction of expansion of concrete during freezing allowing water to escape

into the entrained voids. Depending upon the mineralogical composition of fly ash, the

dosage of air entraining agent fluctuates. Lower the LOI percentage, lower will be the

amount of unburnt carbon, thus dosage of air entrainment agent reduces. However, the

presence of unburnt carbon absorbs air present in the concrete increasing the dosage of

admixture.

Setting time

The setting behavior of fly ash concrete depends upon the amount of cement

replaced, a weather condition at the time of placement, the calcium content of fly ash, w/c

ratio, the type and amount chemical admixture used.

During hot weather, the retardation of setting time due to fly ash reduces, as the

rate of hydration increases. Similarly, fly ash containing high calcium contains reduces the

setting time due to increase in the rate of hydration. However, chilly weather, less calcium

content fly ash and increase in the replacement rate increases the setting time abundantly.

Heat of hydration

Increase in heat of hydration increases the core temperature of concrete causing

early age cracking in massive structures, reducing its durability. Thus, it is extremely

important to maintain the rise in core temperature of concrete while placing for massive

structures. Concrete with low Portland cement and high fly ash content are particularly

suitable for minimizing autogenous temperature rises. HVFA concrete mixes with class F

fly ash is effective in reducing both rates of heat development and the maximum

temperature reached within the concrete (Michael Thomas). Reduction in cementitious


22

materials in concrete helps in reduction of maximum temperature rise in concrete due to a

reduction in rate and heat of hydration. Thus, class C fly ash with high calcium content

would be less effective to improve autogenous temperature rise (FHWA, 2016). However,

they do help in increase in the early strength of concrete.

Effect of fly ash on the properties of hardened concrete

Compressive strength

Fly ash reduces the early age strength of concrete significantly with the increase in

replacement levels of fly ash. This is because pozzolanic reactions are slower than the

hydraulic reactions. However, later age strength will be improved dramatically as the

calcium hydroxide present in the concrete would be reduced to calcium silicate hydrate, a

key factor responsible for the strength of concrete. The rate of early strength is strongly

influenced by temperature, as pozzolanic reactions are sensitive to temperature than

hydraulic reactions. Similarly, calcium content in the fly ash also plays a significant role

in early strength, as it contributes to more hydration of concrete. Researchers have also

shown that if temperature matched curing is to be done, the early strength of fly ash

concrete would be more compared that of ordinary concrete (Michael Thomas).

Creep

Creep would be low in fly ash concrete if loaded at an age when they have attained

the same strength as ordinary concrete as strength gain in fly ash concrete continues.

However, if the fly ash concrete is to be loaded at an early age, then the creep would be

higher than traditional concrete (Michael Thomas).

Drying shrinkage

Amount of water present in the mix and fractional volume of aggregate are the

factors that affect drying shrinkage. Higher the w/c ratio, higher will be the drying

shrinkage and lower the fractional volume of aggregate higher will be the drying shrinkage

as aggregate does not shrink as much as compared to the paste in concrete. In well cured


23

and properly proportioned fly ash concrete, where w/c ratio has been decreased to maintain

the same slump as for ordinary concrete, drying shrinkage is lower than for the ordinary

concrete (Michael Thomas).

Effect of fly ash on the durability of concrete

Abrasion resistance

Abrasion resistance mainly depends on the properties of aggregate and strength of

concrete regardless the presence of fly ash. However, fly ash concrete with stronger

aggregates have proven to be more resistant towards abrasion with the increase in the age

of concrete than ordinary concrete due to increasing strength gain (Michael Thomas).

Permeability and resistance to the penetration of chlorides

The permeability of fly ash concrete decreases phenomenally with the increase in

age of concrete. Thus, at later age, HVFA concrete has very low permeability compared to

that of ordinary Portland concrete for same strength and environmental conditions (Michael

Thomas).

Alkali-Silica reaction

Decreased calcium and alkali content and increased silica content fly ash in

moderate replacement have proven to be the best effective way to mitigate the alkali-silica

reaction in fly ash concrete. This type of fly ash would reduce the risk of ASR more

effectively than the ordinary Portland concrete (Michael Thomas).

Sulfate resistance

Several studies have demonstrated the use of low calcium class F fly ash would be

more effective in providing better resistance to chemical attack. As the time increases, the

reduction of calcium hydroxide to calcium silicate hydrate makes concrete more compact

and less permeable, and the reduced w/c ratio of fly ash concrete helps to increase the

denseness of concrete with time. Thus, these properties increase the soundness of concrete


24

providing better resistance to sulfate and another chemical attack. In contrast, fly ash

concrete that uses class C fly ash does not reduce the amount of CH, thus contributing less

to the soundness of concrete.

Carbonation

Carbonation of concrete is low for well cured, properly – proportioned concrete

with adequate cover provided for the embedded steel regardless of the amount of fly ash

used in concrete (Michael Thomas). Several studies also show that poorly cured fly ash

concrete will carbonate more compared to that of ordinary concrete with same curing

condition (Michael Thomas). The lime present in the concrete will reduce to calcium

carbonate reducing the strength of concrete.

Ca(OH)2 + CO2 Ca(CO)3 + H2O

Resistance to freeze and thaw

Concrete having an adequate air-void system, sufficient strength and frost resistant

aggregates can be resistant to freeze and thaw regardless of the amount of fly ash used

(Michael Thomas). However, the presence of unburnt carbon in the fly ash adsorbs the

entrained air and cannot be available to stabilize air bubbles, thus reducing the amount

entrained air voids (Michael Thomas). Thus, if fly ash with high unburnt carbon content is

to be used, then dosage of air entraining agent needs to be increased.

GGBFS

Slag cement also is known as ground-granulated blast-furnace slag (GGBFS) is also

an industrial waste that has been used in concrete industry for over 100 years now (FHWA,

2016).


25

Figure 2.4 Typical GGBFS used in construction industry (Alibaba, n.d.)

Slag cement is produced from blast-furnace slag, which results from iron-ore in

blast furnace from iron. The iron ore and flux materials are continuously charged in the

furnace and the molten iron and slag are periodically separated and tapped off, then the

molten slag is quenched in water to form a glassy structure that is very much like the

ordinary Portland cement. Figure 2.5 shows the glassy structure of GGBFS under SEM

(Janardhanan, 2015).

Slag cement is more often used nowadays to produce blended cement, i.e., slag is

added to cement plant before cement clinkers are formed (FHWA, 2016). This type of

cement has equivalent properties to that of Type IV cement. The rate of hydration and heat

of hydration is reduced thus decreasing autogenous temperature rise in massive concrete

structure (FHWA, 2016).


26

Figure 2.5 Morphology of GGBFS under SEM (Janardhanan, 2015).

Slag cement is hydraulic and produces calcium silicate hydrate with water, but the

reaction is slower than that of ordinary Portland cement. Even though slag is hydraulic

cement, it does consume CH produced by Portland concrete by binding alkalis in its

hydration products (FHWA, 2016). Thus, giving benefits to both hydraulic and pozzolan

cement.

Slag cement affects both the properties of fresh and hardened concrete. The blended

does have good workability over Portland cement with same w/c ratio but is not as effective

as fly ash due to its glassy structure. Fly ash has perfect spherical like structure offering

greater workability, consolidation, and placement of concrete than slag.

Curing of slag-based cement concrete is very crucial than ordinary concrete as the

hydraulic reaction is very low for slag cement (FHWA, 2016). Thus, also increases the

setting time significantly (FHWA, 2016).

The lower reaction rate, especially at a lower temperature is often overlooked which

could lead to durability issues and at the same time the slower reaction of blended cement


27

can be used as an advantage for mass concrete structures to reduce the maximum rise in

core temperature (FHWA, 2016).

Slag cement binds alkalis in its CSH reaction products and utilizes CH to produce

CSH, thus densifying the concrete structure and reducing the alkali content and making it

less permeable. Hence, slag cement is more resistant towards ASR and external sulfate

attack with the higher replacement of more than 50% (FHWA, 2016).

Rice Husk Ash (RHA)

RHA is an agricultural waste product that has now been widely used as SCM

especially in an agricultural country with a higher production of rice. RHA has higher

amount silica content, less amount of calcium and alkali content when ground finely

attribute a lot of special properties when used as a replacement for cement (Ravinder Kaur

Sandhu, 2016).

RHA is a super good pozzolanic material because of the high content of silica. The

properties of concrete improved by RHA is like that of Fly ash, except for the workability

which is reduced with the increased in replacement level of finely grounded RHA.

Figure 2.6 Several stages of Rice Husk Ash (Thomas, 2018).

Nano silica is a finer form of RHA which is said to improve the compressive

strength, aggregate paste bonding, permeability, split tensile strength, and abrasion


28

resistance. (Ehsani, 2016) But, the production of nano silica is extremely expensive

limiting its use in construction industry.

Pumice

Pumice was used in concrete throughout history even in ancient times during

Roman and Greek civilizations. However, the price and availability of fly ash made it more

economical than pumice (Saamiya Seraj, 2017). Pumice is formed from highly siliceous

volcanic lava. The hot lava quickly cools down to form a glassy structure called pumice.

Pumice is suitable to use as SCM due to its amorphous structure and high silica content

(Saamiya Seraj, 2017).

Figure 2.7 Typical volcanic ash (Geology, n.d.).

With the rising demand for SCM, there has been renewed interest to use pumice,

natural pozzolans an alternative to meet the demand. Researchers have evaluated the

performance of pumice mixtures in terms of compressive strength, durability, and mixture

workability (Saamiya Seraj, 2017).

Some examples of US massive structures with pumice are Los Angeles aqueduct

in 1912, the Friant dam in 1942, the Altus dam in 1945 and the Glen Canyon Dam in 1964

(Saamiya Seraj, 2017).


29

Finely ground pumice, as a natural pozzolan gives better early strength compared

to fly ash and GGBFS as the finer particles act as nucleation for early hydration of cement.

Also, the increased pozzolanic activity also helped in densifying the CSH and making the

concrete low permeable. However, the later age strength was found to be reduced with time

(Saamiya Seraj, 2017). Workability was also reduced significantly as the size of pumice is

finer than Fly ash or GGBFS absorbing the moisture making it little available for paste.

Silica Fume

Silica fume is sub-micron by-product formed in electric arc furnace during the

production of metallic silicon or ferrosilicon alloys. Silica fume is one of the most popular

super pozzolans that consists of 90% silica. Most particles are smaller than 1-mm with an

average diameter of 0.1 mm. Silica fume can replace Portland cement in the range of 9-

15% by mass of cement. However, increase in replacement by more than 15% will result

in negative effects on concrete (FHWA, 2016). Silica fume is often found to be black or

gray in color due to heavy content of carbon and iron.

Commonly, silica fume is used in the ternary blend to improve the properties of

concrete. Finer silica fume helps to densify the CSH and increase the rate of hydration at

early stages with a major reduction in workability. Thus, if silica fume is to be used with

Fly ash or GGBFS, then this ternary blend would compensate the loss in early age strength

due to fly ash and reduced workability due to silica fume.

The advantages of using silica fume are increased pore refinement, improved

strength at an early age, stickiness, ASR resistance and enhanced sulfate resistance

(Aprianti, 2016). Increase in surface area due to fineness increases the amount of water

needed in the mixture, so it is recommended to use water- reducing admixture (Aprianti,

2016). Figure 2.8 shows the denseness of silica fume under SEM.


30

Figure 2.8 Morphology of Silica Fume under SEM (Pittsburgh Mineral and Environmental Technology, Inc, n.d.).

Abrasion resistance is one of the factors to be considered during the construction

of industrial floors, rigid pavement, or other surfaces on which friction forces are applied

due to relative motion between the surface and moving object. Abrasion resistance depends

on environmental condition, aggregate type, amount of aggregates, mixture proportion, use

of SCM, the strength of concrete. Numerous studies show an increase in abrasion resistance

with an increase in replacement level of Silica fume up to 30%. However, the use of water

using admixture is inevitable while using silica fume. Moreover, the price and less

availability of silica fume make it uneconomical.

Metakaolin

Metakaolin is aluminosilicate material that helps to improve the properties of

concrete through micro filler effect and pozzolanic activity, i.e., reacts with slaked lime

produced during hydration of concrete to form calcium silicate hydrate.

Metakaolin is produced by dehydrating kaolin clay in between 650-700oC in an

externally fired rotary kiln into fine particles having an average diameter of less than 1-

mm. These are also called High reactive metakaolin (HRM), as it reacts very quickly due

to increase in surface area and reactivity of particles. Studies have also shown that HRM


31

is responsible for acceleration in the hydration of ordinary Portland cement and its impact

can be seen within 24 hrs. This also reduces the deterioration of concrete by ASR, as the

HRM reduces the amount of lime significantly making concrete less permeable and

stronger. As metakaolin is produced by calcination of purified clay that is used in the

making of china clay, they are white in color. The microstructure of metakaolin is shown

in the Figure 2.9 below.

Figure 2.9 Morphology of Metakaolin under SEM (Hindawi, n.d.).

Although HRM is a pozzolan material like fly ash, the strength at an early age is

increased due to a higher rate of pozzolanic reaction than compared to fly ash. Research

shows the rate of reaction of Metakaolin with calcium hydroxide was almost double than

fly ash and calcium hydroxide reaction.

Increase in the dosage of superplasticizers, a higher price than ordinary Portland

cement, higher dosage to obtain better improvement makes metakaolin an expensive

choice. Moreover, there has been little research done in the field of the behavior of

metakaolin concrete under sustained load which makes us skeptical to use metakaolin

based concrete in massive structures


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Sewage sludge ash

Utilization of sewage sludge ash to replace the mass of cement. would decrease the

amount waste production making environment greener and safer. Sewage sludge ash is the

byproduct produced during the combustion of dewatered sewage sludge in an incinerator.

It is primarily a silty material with some sand-size particles. The specific size range and

properties of the sludge ash depend on the type of incineration system, the source of sludge

ash, and the chemical additives introduced in the wastewater treatment process.

Less research has been done in this area, but if used as an SCM meeting the ASTM

specification, sewage sludge ash has high potential in improving the properties of concrete.

Improved concrete durability, workability, and sustainability of these

supplementary cementitious material have led to a high increase in demand for fly ash and

GGBFS. However, new environmental regulations in different countries have an impact

on the availability of these materials. The source for class “F” fly ash reduced significantly

as the use of coal reduces in the industry. Thus, many researchers are now studying the use

of more natural pozzolans such as; volcanic ash, rice husk ash, palm oil ash, and sewage

sludge ash. These materials have shown the possibility of replacing fly ash and GGBFS.

Moreover, the decrease in early strength is another limitation of SCM. Due to

slower pozzolanic reactions, the rate of strength gain is reduced thus increasing the time of

construction. Different other materials such as; metakaolin and silica fume have been

incorporated to reduce the early strength of high volume fly ash concrete. But, high price

and less availability make these materials uneconomical. Also, the use of superplasticizers

is a must for concrete incorporated with silica fume and metakaolin due to a significant

reduction in a slump. Use of superplasticizers increases the demand of air entraining agent,

thus making it more unsuitable for places prone to freeze and thaw damage.

High volume fly ash is becoming more popular for massive structures as it helps to

reduce autogenous temperature rise in concrete. In contrast, incorporation of silica fume


33

and metakaolin increases the autogenous shrinkage in concrete making it unsuitable for

massive concrete pours.

Use of nanotechnology in concrete has seen a positive possibility in improving the

limitations due to the incorporation of different SCM materials. Nano SiO2 has helped to

improve the early strength of high volume fly ash concrete dramatically without an increase

in autogenous shrinkage. The reactivity of nanoparticles is higher due to a decrease in

particle size, thus increasing the rate of hydration. Researchers have shown that the

pozzolanic reactions are faster in nano incorporated concrete. This property would also

help in increase in the use of natural pozzolans for improved concrete properties.

Nano Concrete

Nanotechnology has been a great area of interest, as these tiny materials have been

able to change the mechanical properties of concrete to a large degree. There has not been

any nanotechnology used commercially so far in construction except for Nano SiO2, which

is produced by grinding rice husk ask very finely to form nano-sized materials. However,

these materials are not as cost-effective and abundantly available as other SCMs. But, if in-

depth research is to be done in this area, there is a possibility of new tech ultra-high

performing, sustainable, economical and durable concrete.

Nano SiO2, Nano TiO2, Nano ZrO2, carbon nanotubes, carbon nanofibers, Nano

CaCO3 has some great possibility in the field of Nano concrete (Hanus, 2008). These

materials tend to change the DNA of concrete by changing the composition of calcium

silicate hydrate. “Smart concrete” and “self-sensing concrete” are getting their way into the

construction industry as they can get the health status of concrete periodically with

deconstructing the infrastructure thus giving us the signal before the fall of any huge

structures (Hanus, 2008).

As much as these materials seem to have ultra-high performing properties, use of

nanotechnology in commercial construction is very slim. Nano TiO2 is used abundantly in

countries like Japan. Similarly, nano SiO2 has been emerging as potential SCM with unique

properties but due to the less commercial application, the price is still expensive. Moreover,


34

CNFs and CNTs are not commercially available yet. Researchers are trying to create more

sustainable and economical way to produce these nanoparticles. Current market values for

different SCM and nanomaterials is provided in the table below.

Table 2.1 Materials price sourced from Alibaba and eBay website

Materials Price per Ton

Nano calcium carbonate $60 - $150

Nano silicon dioxide $7000 - $10000

Metakaolin $300 - $500

Silica fume $500 - $1000

Fly ash $15 - $70

Ordinary Portland cement $50 - $75

In contrast, nano calcium carbonate has a wide range of applications in medical,

pharmaceutical, and different other industry making it widely available. Price of nano

calcium carbonate, as shown in Table 2.1, is less than that of ordinary Portland cement.

Also, the production of nano calcium carbonate utilizes CO2 making it more sustainable.

Use of nano calcium carbonate not only act as filler in concrete, the calcium content also

helps in providing cementitious properties to high volume fly ash concrete. Similarly, the

rate of hydraulic reaction is faster than for the ordinary Portland concrete. Thus, this study

has been a step towards producing economical, sustainable, durable and high-efficiency

concrete with the use of nanomaterials.

Nano Calcium carbonate

Nano calcium carbonate (Nano CaCO3), is another nanoparticle that has been

produced commercially for the medical, and other industry but has not been used

commercially in the construction industry. However, these tiny white particles have been

shown to improve the mechanical properties of concrete dramatically (Faiz U.A. Shaikh,

2014). This thesis describes the test done to observe the change in properties of ordinary

concrete and fly ash concrete with the addition of nano calcium carbonate and it has shown

to improve several properties of concrete including durability and strength.


35

Figure 2.10 Schematic figure to produce nano calcium carbonate (Eda Ulkeryildiz, 2016).

Different technologies have been emerging to produce rice like hollow nano

calcium carbonate in the sustainable and efficient way and make it more economical.

Normally, 98% pure carbon dioxide is passed through liquid calcium hydroxide, that is

continuously stirred to produce precipitated nano CaCO3 (Eda Ulkeryildiz, 2016). The

schematic figure to produce nano calcium carbonate is shown in Figure 2.11. Similarly,

different shapes and size of nano calcium carbonate can be produced by altering the

pressure of carbon dioxide into the solution, the speed of agitation of solution, and different

pH (Gupta, 2004). Figure 2.12 shows varied sizes of nano calcium carbonate produced.


36

Figure 2.11 Varied sizes of nano calcium carbonate (Gupta, 2004).

The production of calcium carbonate nanoparticle makes it more sustainable by

utilizing CO2. This idea could be incorporated in the concrete plant to utilize CO2 produced

during calcination process and produce nano CaCO3 which could be added in the clinkering

process to react with cement clinkers making the reaction faster and reducing the

temperature. Hence a new type of cement could be produced by this process that will have

better-performing cement than the ordinary cement with the expense of reduced heat

energy and reduced CO2 production.


37

CHAPTER III

MATERIALS

This section describes all materials used to produce concrete specimens for property

evaluations. Coarse aggregate, fine aggregate, ordinary Portland cement, and fly ash were

sourced from a nearby concrete plant located in Lubbock. However, nano calcium

carbonate was ordered from China through Alibaba website.

Coarse Aggregate

Coarse aggregate used in this project is limestone which is lighter than gravels or

other crushed stones. ¾ inch nominal maximum size conforming to ASTM C 33-86 was

used. Absorption, moisture content, specific gravity, and sieve analysis test were conducted

to identify different properties of coarse aggregate using ASTM procedures.

Table 3.1 Properties of Coarse Aggregate

Properties Values

Specific gravity 2.4

Absorption 0.8%

Moisture content 2%

Gradation Grade 5

Fine Aggregate

Siliceous river sand was used for this project. It met all the performance requirements

conforming to ASTM C33-86. Similarly, specific gravity, absorption, moisture content,

and sieve analysis test were performed to identify different properties of fine aggregate

using ASTM procedures.


38

Table 3.2 Properties of fine aggregate

Properties Values

Specific gravity 2.5

Absorption 0.3%

Moisture content 3.8%

Fineness modulus 2.6

Fly Ash

Class “C” fly ash was used which was sourced from a local concrete plant from

Lubbock, Texas. The mill certificate given in the appendix, the summary of which is

illustrated in Table 3.3, shows mineralogical composition of this fly ash.

Table 3.3 Composition of Fly ash

Ordinary Portland cement

One type of Portland cement was used throughout the project. Type I/II ordinary

Portland cement meeting ASTM C150-86 requirements was used, and the mill certificate

given in the appendix show mineralogical composition of this cement. All specimens were

cast during March 2018.

Composition Values (%)

SiO2 35.58

Al2O3 18.27

Fe2O3 7.38

CaO 25.88

MgO 5.27

SO3 1.43

Moisture content 0.07

Loss on ignition 0.2

Eq. Na2O 2.15


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Nano Calcium Carbonate

Nano calcium carbonate was ordered from China through Alibaba website. 98% pure

white precipitated nano CaCO3 has an average diameter of 40 nm. Table 3.3 provides the

properties of nano calcium carbonate provided by the seller from China.

Table 3.4 Composition of nano CaCO3

Properties Values

Moisture content <0.5

Surface area >40 m2/g

Average size 40 nm

CaCO3 % >95

Mg0 % <0.5


40

CHAPTER IV

METHODS

This section includes all the procedure and methods used in conducting a different test

for the experimental investigation. Ordinary Portland cement was replaced by 35% (F35)

and 45% (F45) fly ash by mass of cement. F35 and F45 were further modified by replacing

1%, 3%, and 20% of cement with nano calcium carbonate. Concrete mix design for all the

samples is attached in the appendix. The test matrix is shown in Table 4.1.

Table 4.1 Design matrix

Nano CaCo3 Fly ash

0 0

1 35

3 45

20 -

Properties of coarse aggregate

Tests were conducted to identify different properties of coarse aggregate such as;

absorption, moisture content, specific gravity and sieve analysis using ASTM procedures.

All the procedures are further explained in detail in the sections below.

Absorption and specific gravity of coarse aggregate

Absorption and specific gravity of coarse aggregate were conducted in accordance with

ASTM C127 procedures:

✓ Samples were immersed in water for 24 hours.

✓ Samples were then removed from the water and was air dried using a cotton cloth

and cold air to bring it to the saturated surface dry condition.

✓ Then, the mass of sample was recorded in saturated surface dry condition (Mair).


41

✓ After determining the mass in air, samples were immediately placed in a container

and apparent mass in water was recorded (Mwater).

✓ Finally, the samples were oven dried at a temperature of 108oC for 24 hrs. and was

weighed again (Movendried).

✓ Following formulas were used to calculate absorption and specific gravity of coarse

aggregates.

Specific gravity = Movendried/ (Mair - Wwater)

Absorption = (Mair - Movendried) / Movendried x 100 (%)

Absorption and specific gravity of fine aggregate

Absorption and specific gravity of coarse aggregate were conducted according to

ASTM C127 procedures:

✓ Samples were immersed in water for 24 hours.

✓ Samples were then removed from the water and was air dried using a cotton cloth

and cold air to bring it to the saturated surface dry condition.

✓ Pycnometer filled with water up to the calibration mark was weighed (B).

✓ The saturated surface dried sample was weighed (A) and then introduced in the

pycnometer and water was again filled up to the calibration mark (C).

✓ The mass of sample was recorded in saturated surface dry condition (S).

✓ The remaining sample was then oven dried at a temperature of 108oC for 24 hrs.

and was weighed again (O).


aggregates.

Specific gravity = A/ (B+A-C)

Absorption = (S- O) / O x 100 (%)


42

Moisture content for coarse and fine aggregate

Moisture content for coarse and fine aggregate was conducted following ASTM C566

procedures:

✓ 500gm of the sample for fine aggregate and 1000gm of coarse aggregate was oven

dried for 24 hrs. at 105oC.

✓ Oven dried samples were then weighed to calculate the moisture content.


aggregates.

Moisture content = (Mass of the sample - Mass of oven dried sample)/Mass of oven

dried sample x 100 (%)

Sieve analysis for coarse and fine aggregate

Sieve analysis for coarse and fine aggregate was conducted following ASTM C136

procedures:

✓ Sieves with suitable openings are selected for both coarse and fine aggregates.

✓ 500gm of fine and 1000g of coarse aggregate was sieved in their respective

mechanical sieve shaker.

✓ Sieving was done for sufficient period such that not more than 1% by mass of the

material retained on any individual sieve will pass that sieve during 1 min of

continuous hand sieving.

✓ Percent retained, and percent passing was then calculated, and the gradation is

shown in the graph in the appendix.

Tests conducted on fresh concrete

Workability and finish ability of concrete is one of the most critical properties of

concrete. Concrete with low workability would not get in the commercial market even

though the strength parameters of concrete is good enough. Slump test, setting test, and the


43

calorimeter test were done to study the change in fresh concrete properties after addition

of nano CaCO3.

Workability

Slump test is conducted following ASTM C143 procedures. A sample of freshly mixed

concrete was taken out for the slump test.

✓ This test was carried out in metallic mold also known as slump cone, that is open

at both ends and has attached handles.

✓ Cone was placed on a hard-non-absorbent surface and was filled in three layers

with fresh concrete by tamping each layer 25 times.

✓ The concrete was struck off at top of the cone to smooth out the surface and the

mold was lifted carefully vertically upwards.

✓ Finally, the slump of the concrete is measured by measuring the distance from the

top of the slumped concrete to top of the cone.

Setting time

Setting time was conducted following the ASTM C403 procedures.

✓ The fresh mortar was prepared using the concrete mixer, that has a minimum

capacity of 0.5 ft3.

✓ Bleed water was removed prior to the testing by using the plastic pipet and the mold

was tilted at 100 for the facilitation of bleed water.

✓ After an elapsed time of 4-5 hrs., the needle of appropriate size was inserted

depending upon the setting time of the mortar.

✓ Gradually and uniformly a vertical force was applied until the needle penetrates the

mortar at a depth of 1 inch.

✓ Time and force required to produce 1-inch penetration was recorded

✓ At least six penetration tests were done at an interval of ½ to 1 hr.


44

Heat of hydration

X-Cal, a software that records and extracts the data for the heat of hydration of concrete

from semi-adiabatic calorimeter was used in conducting calorimeter test to study the rate

of increase in temperature during hydration of concrete. Following steps were followed:

✓ Four cylinders 4” by 8” were filled with fresh concrete and was stored in the semi-

adiabatic container.

✓ The cable connecting the container and the system with X-Cal software was

connected and the software was left for logging the data.

✓ After 72 hours of logging, the data was extracted from the software.

Tests conducted on hardened concrete

Hardened concrete properties help us to identify the behavior of concrete structures

under different environmental and structural loading. Soundness of concrete helps us to

identify the durability of structures. Different tests such as compressive strength, modulus

of elasticity, rapid chloride penetration test, and shrinkage ring test were conducted to

identify the properties of hardened concrete under different loading conditions.


Compressive strength was conducted following ASTM C 39 procedures:

✓ Three moist cured specimens were prepared for each sample that met the specific

requirements mentioned in ASTM C39.

✓ The compressive strength of each sample was measured for 1 day, 3 days, 7 days

and 28 days respectively in a moist condition, i.e. immediately after it was taken

out of the curing tank.

✓ The bearing surface of the sample was cleaned, and bottom and the top bearing

plate was placed on top and bottom of the sample

✓ The sample was aligned with the axis of the testing machine.

✓ Testing machine was turned on and different properties of samples were entered,

and the rate of loading was fixed at 35 psi/s which was kept constant for all samples.


45

✓ The load was then applied till the sample failed and the maximum load taken by

the sample was recorded.

Modulus of elasticity

Modulus of elasticity was conducted using free resonance testing device. Following

procedures were followed.

✓ Moist cured specimens were prepared for each sample.

✓ Modulus of elasticity was measured for 1 day, 3 days, 7 days and 28 days

respectively.

✓ The specimen was placed on a smooth surface, cable was connected at one end at

the center of the cylindrical specimen to record the frequency.

✓ Then, the other end was hammered slowly to record the frequency passed through

the specimen.

✓ Thus, the recorded frequency was used to calculate the modulus of elasticity for

each sample in wet condition.

Shrinkage Ring test

Shrinkage ring test was conducted following ASTM C1581 procedures:

✓ Steel ring with strain gages was set onto the base plate.

✓ The inner ring was centered with the 3 turnbuckles.

✓ The outer stainless ring was then set onto the base plate.

✓ Similarly, the outer ring was fixed with 2 turnbuckles in the same way as that for

the inner ring.

✓ The green steel beam was laid at last and was fixed with two threaded rods.

✓ The freshly mixed concrete mortar was used to fill the mold.

✓ The mold was filled in 2 layers, each layer was compacted 75 times using a 10 mm

diameter rod.

✓ The compaction was then finished off with a leveled surface with minimum

manipulation.


46

✓ Coarse aggregate used in this test had a maximum size of 0.5”.

✓ After the completion of compaction, the turnbuckles and the butterfly nuts were

immediately loosened.

✓ After 2 minutes, the strain gage amplifier was connected to the data logger to the

data acquisition system, to record the time and begin monitoring strain gages at an

interval of 10 minutes.

✓ The sudden drop in the strain would indicate the time of the first crack.

Design matrix

Following design, the matrix was used to conduct the different test. Fly ash was used

at a replacement level of 35% and 45%. Similarly, nano calcium carbonate was used at

replacement level of 1%, 3%, and 20%.


47

Table 4.2 Different notation used to differentiate samples.

Notation Definition

0 - 0 0% Nano Calcium Carbonate and 0% Fly Ash













48

CHAPTER V

RESULTS

This section presents the finding from various testing described previously investigate

the behavior of concrete as affected by the addition of nanoparticles.

Workability

Workability of fresh concrete was measured using slump test. Higher the slump,

better will be the workability of fresh concrete. However, higher slump also tends to

increase plastic shrinkage crack in concrete which decreases the durability of concrete.

Addition of 1% and 3% nanoparticles had little to no effect on the slump for concrete

without fly ash. However, the slump was reduced significantly for fly ash concrete after

the addition of nanoparticles. F35 and F45 slump were reduced by 2 inches and 2.5 inches

respectively after the addition of 3% nano CaCO3. Thus, the workability of normal concrete

with nano CaCO3 was not compromised without the decrease in a slump. On the other hand,

for high volume fly ash concrete, the slump was reduced significantly. A significant

decrease in bleed water was observed specifically for fly ash concrete. It appears that nano

CaCO3 blocks bleeding water in the concrete containing fly ash, as silica fume does,

resulting in decrease in workability. However, it is not known why the same phenomenon

is not observed in concrete without fly ash. Further investigation is warranted. Change in

a slump for the control sample, fly ash sample and sample with the addition of nano CaCO3

is shown in the Figure 5.1.


49

Figure 5.1 Slump for different samples.

Setting test

The setting test is a measure of the rate of hydration of concrete and determines the

initial, and final sets, by evaluating penetration resistance of concrete. One of the main

disadvantages of using fly ash is the increase in setting time, thus elongating the time of

construction. However, use of nano CaCO3 has helped in decreasing setting time of high

volume fly ash concrete by up to 3 hours. Use of high volume fly ash is ideal for many

other applications such as in massive structure, but the prolonging setting times makes the

construction more challenging. Similarly, the final set of ordinary concrete was reduced by

up to 4 hours. The curvature of the setting test graph had a similar pattern for both ordinary


50

concrete and fly ash concrete. The graph followed the same pattern until initial set, but the

slope was steeper after the initial set of samples with nano CaCO3, which indicated the

increase in the rate of hydration and/or stiffening of the cement matrix by small particles

of nano CaCO3. Penetration resistance for all samples is shown in the Figures 5.2 through

5.5. Red line indicates the initial set of concrete and blue lines indicates the final set of

concrete.

Figure 5.2 Penetration resistance for ordinary concrete, and 1% and 3% nano replacement in ordinary concrete


51

Figure 5.3 Penetration resistance for F35, and 1% and 3% replacement of nano in F35

Figure 5.4 Penetration resistance for F45, and 1% and 3% replacement of nano in F45


52

Figure 5.5 Setting time for all samples

Heat of hydration

The heat of hydration for all representative samples was observed using semi-

adiabatic calorimeter. Cylinders of size 4” by 8” were filled with fresh concrete and was

placed in the calorimeter. The heat of hydration was then recorded for 72 hours, and the

data was extracted using X-Cal software. This test is a measure of the heat of hydration


53

produced during the hydration of calcium silicate hydrate. The Higher the heat of

hydration, the higher the rate of hydration, resulting in the decrease in setting times as

discussed above and potentially higher early strength. However, this was not true in the

case of concrete added with nano calcium carbonate. Although the rate of hydration was

dramatically higher for concrete with nano calcium carbonate as seen from the setting test,

the heat of hydration was lower than that for the control sample. However, the heat of

hydration was increased significantly for F35 with 3% nano calcium carbonate.

Figure 5.6 Heat of hydration for samples 0 – 0, 3 – 0, 3 - 35

Figure 5.6 illustrates the heat of hydration for different samples during the 72 hours.

Sample 1 is controlled sample which has the highest heat of hydration, i.e. 0% fly ash and

0% nano calcium carbonate. Sample 2 is 3% nano and 0% fly ash which has the slightly

lower heat of hydration than ordinary concrete. Similarly, sample 3 is 35% fly ash with 3%

nano calcium carbonate which has a higher heat of hydration, than sample 4, 35% fly ash

and 0% nano calcium carbonate. This shows the improvement in early hydration for 35%

fly ash concrete.


54

Figure 5.7 Heat of hydration for samples 0 – 0, 1 – 0, 1 - 45

Similarly, Figure 5.7 represents control sample and fly ash concrete with 45%

replacement. Sample 1 with 0% fly ash and 0% nano calcium carbonate has the highest

heat of hydration. Sample 3 with 0% fly ash and 3% nano calcium carbonate has lower

heat of hydration than control specimen which contradicts with the expected rate of

hydration, which was higher for ordinary concrete with 3% nano calcium carbonate.

Similarly, sample 2 with 45% fly ash and 1% nano has shown to improve the heat of

hydration than sample 3 which is 45% fly ash with 0% nano calcium carbonate.

This indicates the potential of increase in early age strength without an increase in

autogenous temperature rise, unlike silica fume and metakaolin. This property can be

advantageous for pouring concrete into massive structures.


Compressive strength has been most widely used as an indicator of the concrete

quality, since other durability properties are related to compressive strength, even though

the correlation is not as strong as desired. One great advantage of compressive strength

compared with other properties is that the time required for the evaluation of compressive


55

strength is quite short and the testing itself is quite simple. Other advantages include rather

small testing variability, which is a requirement for any quality control testing. Concrete

strength includes the denseness, soundness, resistance to different chemical attack,

abrasion resistance, and many other factors. Compressive strength tests were performed on

cylinders cured for 1 day, 3 days, 7 days and 28 days. Addition of nano calcium carbonate

in ordinary concrete and in fly ash concrete improved early age compressive strength up to

98%. However, the later age strength varied according to the amount and type of fly ash

and nano CaCO3 used. The compressive strength of different samples for 1day, 3 days, 7

days and 28 days are shown in Figures 5-8 through 5-11.

Figure 5.8 Compressive strength for samples 0 – 0, 1 – 0, 3 - 0


56

Figure 5.9 Compressive strength for samples 0 – 35, 1 – 35, 3 – 35

Figure 5.10 Compressive strength for samples 0 – 45, 1 – 45, 3 - 45


57

Figure 5.11 Compressive strength for all samples

Elastic modulus

Modulus of elasticity determines the resistance of a material to elastic deformation.

The stiffer material has higher modulus. This is also defined by the slope of the stress-

strain curve in the elastic deformation curve. Modulus of elasticity reduced for ordinary

concrete with nanoparticles. Similarly, the modulus of elasticity was reduced for fly ash

concrete with the addition of nanoparticles. Usually, increase in compressive strength


58

enhances the modulus of elasticity of concrete making it stiffer and more brittle. However,

the addition of nanoparticle increased the compressive strength of normal concrete and fly

ash concrete without a significant increase in elastic modulus. This finding is significant

since increased strength without the comparable increase in modulus would result in more

crack resistance concrete. This aspect of concrete material property modifications due to

the introduction of nano CaCO3 has significant practical implications and further

evaluations are warranted. Figures 5-12 through 5-15 present the variations in concrete

modulus with age for concretes evaluated in this study.

Figure 5.12 Elastic modulus for samples 0 – 0, 1 – 0, 3 - 0


59




60

Figure 5.15 Elastic modulus for all samples

Shrinkage Ring Test

This test was conducted to determine the resistance of concrete against shrinkage

cracking. The apparatus consists of an outer ring and an inner ring. Outer ring is removed

after the concrete is set. The inner ring has the strain gauges to measure the strain in ring

due to drying of concrete. Freshly mixed concrete was placed in the mold until the strain


61

in the inner ring reduced by 30 microns or more. This indicates the occurrence of first crack

in concrete. Normally, ordinary concrete will have first crack due to drying shrinkage at

around 140 to 150 hours after the placement of concrete in the mold.

Figure 5.16 shows the strain values for ordinary concrete with 3% nano calcium

carbonate. It shows that a crack occurred at 209 hours after the concrete placement, and the

strain at the time a crack occurred was about 75 micro strain. To evaluate the crack

resistance of concrete containing nano CaCO3 with respect to the ordinary concrete, the

time it took for a crack to have occurred in this concrete has to be compared with that in

ordinary concrete. Preliminary testing for ordinary concrete indicated a cracking at much

earlier time. This shows the improvement in resistance of concrete towards drying

shrinkage crack. This can be related to increase in strength of concretes containing nano

CaCO3 without increased modulus of elasticity. As discussed earlier, this aspect of

improved crack resistance of concrete containing nano CaCO3 could have significant

practical implications and further efforts will be made to validate this initial finding.

Figure 5.16 Steel ring strain versus specimen age, days


62

CHAPTER VI

DISCUSSIONS

This thesis describes the efforts made to investigate the effects of nano CaCO3 in

concrete on the modifications in the properties of concretes with and without fly ash.

Addition of 1% and 3% nanoparticles had little to no effect on the workability of concrete.

Fly ash concrete with nanoparticles reduced the slump and bleeding water.

In concrete with fly ash, the incorporation of nano CaCO3 increased the rate of

hydration, resulting in improved early strength. On the other hand, the heat of hydration

was slower for ordinary concrete with nanoparticles. These findings are somewhat

contradictory to the early-age strength variations. Further testing is needed to reconcile this

seemingly contradictory results.

Increase in early penetration resistance was observed with the addition of nano calcium

carbonate which is expected due to increase in the rate of hydration. This was due to the

faster reaction of nano calcium carbonate, increasing the rate of both hydraulic and

pozzolanic reactions.

Addition of nanoparticles improved the early age strength of fly ash concrete and

ordinary concrete due to a higher rate of hydration. However, later age strength depended

on many factors such as the type of fly ash used, amount of silica present in the fly ash,

amount of replacement. Concrete replaced with 35% fly ash along with nano calcium

carbonate displays significant improvement in compressive strength at an early age. In

contrast, 45% fly ash with nano calcium carbonate shows improvement of strength at an

early age and later age, later age strength being more prominent.

Early age strength is determined by the rate of reaction and later age strength is

determined by the amount and the bonding of calcium silicate hydrate. Size of

nanoparticles contributes to an increase in the rate of reaction due to the high reactivity of

the particles. Thus, the early age strength and early penetration resistance were improved

significantly for ordinary concrete and fly ash concrete with the addition of nanoparticles.


63

Due to the combination of both pozzolanic and hydraulic reaction, the 28-day strength for

35 % fly ash was almost equal to the strength of control specimen. But, with the addition

of nano calcium carbonate, although the early age strength was improved, later age strength

was lower. This could be the result of the inappropriate ratio of calcium and silica content

present in the concrete, thus decreasing the amount of CSH formed. As the time increases,

the pozzolanic reaction increases depleting the amount of silica, accordingly less silica will

be available for complete hydration of calcium content. Thus, if the calcium and silica

content are well proportioned, then the nano calcium carbonate would perform better with

siliceous SCM such as class “F” fly ash, rice husk ash, and volcanic ash-producing high

performing nano concrete. These are hypotheses based on the observations of limited

testing results, and further evaluations are needed to confirm whether these hypotheses are

valid.

The limitation of using nano calcium carbonate is the inconsistency with the data due

to poor dispersion of particles. One of the main challenges would be to disperse the nano

calcium carbonate uniformly in the concrete mix due to its high reactive surface. Improper

dispersion would lead to bigger chunks of unreacted nanoparticles, decreasing the bond of

CSH and thus decreasing the strength of concrete.

As explained earlier, if the production of nano calcium carbonate was to be done in

the cement plant itself to produce blended nano cement, a new type of cement would be

formed that would be more sustainable and durable than ordinary Portland cement, while

solving the uniform dispersion issue.


64

CHAPTER VII

SUMMARY & RECOMMENDATIONS

Nanotechnology has been an emerging topic in the field of concrete, as it helps to

improve the mechanical properties of concrete by changing the composites of calcium

silicate hydrate at the nano level. Some researchers have also shown the improvement of

early strength of High Volume Fly Ash concrete (HVFA) concrete after addition of

nanoparticles such as TiO2, nano SiO2, carbon nanotubes etc. Silica fume and Metakaolin

are the most commonly used SCM to improve the early age strength of HVFA concrete.

However, as much as these pozzolanic materials help to improve the impact resistance and

abrasion resistance, there has been trivial improvement in early age strength of HVFA.

This study presents the results of an experimental investigation conducted in

incorporating nano CaCO3 in HVFA to improve its early strength. Ordinary Portland

cement was replaced with class C Fly Ash at the level of 35% and 45% to produce HVFA.

F35 and F45 were furthered modified using nano CaCO3 at the level of 1%, 3%, and 20%.

All types of concrete mixtures were cured for 3, 7 and 28 days. Slump test, setting test, and

calorimeter test were conducted on fresh concrete. Similarly, compression test, elastic

modulus and shrinkage ring test were conducted on hardened concrete. Test results

indicated up to 20% increase in compression for HVFA mixed with nano CaCO3, and up

to 25% increase in compression for ordinary concrete mixed with nano CaCO3. However,

when cement was replaced with nano CaCO3, the elastic modulus was lower for both the

ordinary concrete and fly ash concrete. This finding has significant practical implications

since more crack resistant concrete can be produced with the introduction of nano CaCO3

without compromising structural capacity of the concrete elements. Similarly, the rate of

hydration increased with the addition of nano CaCO3, which contributed to higher early

strength of concrete.

Based on the observations of properties of concrete evaluated in this study with and

without nano CaCO3, it appears that the incorporation of nano CaCO3 in concrete could


65

improve overall performance of concrete without sacrificing constructability and increase

in cost.

Different unique behaviors of concrete with nano CaCO3 must be furthered studied

and experimented thoroughly before reaching a concluding remark. As, this is a new area

of research, further extensive research of these materials can only lead us to definite

conclusion.

Moreover, this thesis was focused on early strength of concrete, more research is

needed to evaluate the durability of concrete with nano CaCO3. Material properties such as

resistant to ASR, sulfate attack, RCPT, drying shrinkage, behavior of nano concrete under

creep and sustained load needs to be further evaluated. Similarly, this study was

experimented only with class C fly ash but, use of nano calcium carbonate with more

siliceous pozzolans is another interesting area of research that could lead to further

improved concrete properties.

Furthermore, developing an optimum replacement level of nano calcium carbonate

for different types of concrete i.e., ordinary concrete, fly ash concrete, blended concrete

etc., is another critical issue that needs to be addressed to make this material commercially

feasible.


66

REFERENCES

Alibaba. Retrieved from https://www.alibaba.com/.

Aprianti, E. (2016). A huge number of artificial waste can be supplementary cementitious

material (SCM) for concrete production. Journal of cleaner production.

Eda Ulkeryildiz, S. K. (2016). Rice-like hollow nano-CaCO3 synthesis. Journal of

crystal growth.

Ehsani, A. (2016). Effect of nanosilica on the compressive strength development and

water absorption properties of cement paste and concrete containing Fly ash.

KSCE Journal of Civil Engineering.

Faiz U.A. Shaikh, S. W. (2014). Mechanical and durability properties of high volume fly

ash (HVFA) concrete containing calcium carbonate (CaCO3) nanoparticles.

Construction and Building Materials.

FHWA. (2016). Supplementary cementitious materials.

Geology. Retrieved from https://www.geology.com.

Gupta, R. (2004). Synthesis of Precipitated calcium carbonate Nanoparticles Using

Modified Emulsion Membranes. Georgia Institute of Technology.

Hanus, M. J. (2008). Nanotechnology innovations for the construction industry. Progress

in materials science.

Hindawi. Retrieved from https://www.hindawi.com/.

Janardhanan, T. (2015, June). Properties of Foundry sand, Ground Granulated Blast

Furnace slag and Bottom Ash Basd Geopolymers under Ambient Conditions.

Periodica Polytechnica Civil Engineering.

Michael Thomas, P. P. (n.d.). Optimizing the use of fly ash in concrete. Portland Cement

Association.

Pittsburgh Mineral and Environmental Technology, Inc. Retrieved from

www.pmetlabservices.com.


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Ravinder Kaur Sandhu, R. S. (2016). Influence of rice Husk ash on the properties of self-

compacting concrete: A Review. Construction and Building Materials.

Saamiya Seraj, R. C. (2017). The role of particle size on the performance of pumice as a

supplementary cementitious material. Cement and Concrete Composites.

SOBOLEV, K. (2016, 10 2). Modern developments related to natotechnology and

nanoengineering of concrete. Review article, p. 132.

THE CONCRETE COUNTERTOP INSTITUTE. Retrieved from

www.concretecountertopinstitute.com.

The science of concrete. Retrieved from http://iti.northwestern.edu/cement/index.html.

Thomas, B. S. (2018). Renewable and Sustainable Energy Reviews.

Won, D. M. (2016). Concrete materials class.


68

APPENDIX

Table A 1 Sieve Analysis of coarse aggregates

Diameter

(mm)

Wt.

retained

(lbs.)

Percent

Retained

Cumulative

Retained

Percent

Passing

75.00 0.20 0.79 0.79 99.21

63.00 1.15 4.54 5.33 94.67

50.00 5.45 21.50 26.82 73.18

12.70 14.25 56.21 83.04 16.96

4.75 1.45 5.72 88.76 11.24

Pan 2.84 11.20 99.96

Figure A 1 Gradation of coarse aggregates used

0.0

20.0

40.0

60.0

80.0

100.0

120.0

01020304050607080

Per

cen

t fi

ner

Diameter (mm)

Coarse Aggregate


69

Table A 2 Sieve Analysis of fine aggregates

Diameter

(mm) Wt

retained

(lbs.)

Percent

retained

Cumulative

retained

Percent

passing

4.75 6.13 0.85 0.85 99.15

2.36 43.04 5.94 6.78 93.22

1.18 113.98 15.72 22.50 77.50

0.60 231.01 31.86 54.37 45.63

0.30 205.97 28.41 82.78 17.22

0.15 91.21 12.58 95.36 4.64

Pan 17.34 2.39 97.75

Figure A 2 Gradation of fine aggregates

0

20

40

60

80

100

120

0.1 1 10

Per

cen

t fi

ner

Diameter (mm)

Fine Aggregate


70

Table A 3 Mix design for all the samples

Mix Cement(lbs.) Coarse

Aggregate

(lbs.)

Fine

Aggregate

(lbs.)

Water

(lbs.)

Fly

ash

(lbs.)

Nano

CaCO3

(lbs.)

0-0 680 1745 1248 285 0 0

1-0 673 1745 1248 285 7 0

3-0 660 1745 1248 285 20 0

0-35 442 1745 1248 285 0 238

1-35 435 1745 1248 285 7 238

3-35 422 1745 1248 285 20 238

0-45 374 1745 1248 285 0 306

1-45 367 1745 1248 285 7 306

3-45 354 1745 1248 285 20 306

Table A 4 Setting time data for sample 0-0

Time (mins) Force (lbs.) Area (sq. in) Resistance (psi)

270 44 0.5 88

330 100 0.5 200

390 140 0.25 560

450 120 0.1 1200

580 185 0.05 3700

645 155 0.025 6200


71



170 40 0.25 160

230 40 0.1 400

300 80 0.1 800

330 130 0.1 1300

360 132 0.05 2640

400 114 0.025 4560



180 40 0.5 80

240 84 0.25 336

285 100 0.1 1000

335 170 0.05 3400

355 110 0.025 4400


Time (mins) Force(lbs.) Area (sq. in) Resistance (psi)

340 32 0.5 64

420 80 0.5 160

475 80 0.25 320

520 68 0.1 680

580 134 0.1 1340

640 120 0.05 2400

730 120 0.025 4800


72



300 32 0.5 64

380 86 0.5 172

450 88 0.25 352

500 72 0.1 720

560 158 0.1 1580

620 142 0.05 2840

680 108 0.025 4320



300 38 0.5 74

330 52 0.5 102

400 56 0.25 220

445 38 0.1 380

485 86 0.1 860

540 98 0.05 1960

610 88 0.025 3520

655 118 0.025 4720


73



300 22 0.5 44

360 38 0.5 76

470 60 0.25 240

510 90 0.25 360

590 78 0.1 780

650 66 0.05 1320

695 108 0.05 2160

755 100 0.025 4000



390 50 0.5 100

420 58 0.25 232

465 110 0.25 440

515 72 0.1 720

545 96 0.1 960

575 71 0.05 1420

605 118 0.05 2360

635 185 0.05 3700

660 120 0.025 4800


74



360 34 0.5 68

420 38 0.25 152

540 96 0.25 384

580 174 0.25 696

620 120 0.1 1200

655 94 0.05 1880

685 130 0.05 2600

755 110 0.025 4400

Table A 13 Compressive strength for all samples for 1 day

Mix Compressive strength (psi) Average(psi)

0--0 1023 974 987 995

0--35 390 358 342 363

0--45 58 62 64 61

1--0 1900 1890 1810 1867

1--35 480 520 510 503

1--45 190 182 187 186

3--0 1880 1900 1856 1879

3--35 750 710 812 757

3--45 61 50 60 57


75

Table A 14 Compressive strength for all samples for 3 days


0--0 3100 3000 3035 3045

0--35 2300 2200 2320 2273

0--45 2046 2035 2010 2030

1--0 3830 3780 3740 3783

1--35 2420 2460 2390 2423

1--45 2020 2035 2047 2034

3--0 3750 3788 3810 3783

3--35 2650 2600 2590 2613

3--45 1820 1800 1790 1803



0--0 4100 4150 4130 4127

0--35 3430 3487 3412 3443

0--45 3440 3448 3358 3415

1--0 5280 5235 5300 5272

1--35 3910 3930 3900 3913

1--45 4040 4008 4089 4046

3--0 4817 4800 4783 4800

3--35 4060 4048 4110 4073

3--45 3550 3678 3530 3586


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0--0 6650 6630 6665 6648

0--35 6660 6700 6670 6677

0--45 5500 5350 5420 5423

1--0 6950 6900 6890 6913

1--35 6500 6510 6480 6497

1--45 6780 6900 6820 6833

3--0 5450 5420 5410 5427

3--35 6100 6220 6180 6167

3--45 5700 5660 5675 5678

Table A 17 Elastic modulus frequency for all samples for 1 day

Mix Frequency (Hz) Average

0—0 8539 8319 8584 8480

0—35 8069 7968 7814 7950

0—45 7210 7175 7239 7208

1—0 8381 8552 8498 8477

1—35 7598 7667 7473 7579

1—45 7200 7154 7271 7208

3—0 8349 8243 8212 8268

3—35 7769 7681 7765 7738

3—45 7022 6926 6882 6943


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Table A 18 Elastic modulus frequency for all samples for 3 days


0--0 9300 9248 9277 9275

0--35 8721 8612 8557 8629

0--45 8660 8531 8696 8629

1--0 9070 8930 9030 9010

1--35 8585 8444 8412 8480

1--45 8960 8967 8944 8957

3--0 8991 8983 9038 9004

3--35 8804 8731 8700 8745

3--45 8321 8333 8468 8374



0--0 9398 9513 9550 9487

0--35 9328 9347 9150 9275

0--45 9202 9276 9188 9222

1--0 9560 9450 9520 9510

1--35 9350 9200 9275 9275

1--45 9249 9087 9171 9169

3--0 9578 9550 9333 9487

3--35 9200 9115 9192 9169

3--45 9088 9132 9128 9116


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0--0 10030 10021 10001 10017

0--35 9859 9874 9841 9858

0--45 9644 9679 9615 9646

1--0 9700 9670 9730 9700

1--35 9588 9640 9671 9633

1--45 9800 9778 9837 9805

3--0 9743 9818 9800 9787

3--35 9720 9748 9698 9722

3--45 9569 9649 9561 9593


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Figure A 3 Slump test conducted for fresh concrete

Figure A 4 Preparation of sample for setting time


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Figure A 5 Compressive strength Testing machine

Figure A 6 Concrete mold after removal of outer ring for shrinkage ring test


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Figure A 7 Data logger used for shrinkage ring test

Figure A 8 Compaction of sample in the plastic mold for compressive strength and elastic modulus


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Figure A 9 Elastic modulus Test

Figure A 10 Semi-adiabatic calorimeter used for determining heat of hydration on fresh concrete

copyright 2018, lochana poudyal

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