iii Table of contents

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iii

CHAPTER - I: INTRODUCTION ... 1

G

ENERAL INTRODUCTION

... 2

M

OTIVATION FOR THE RESEARCH

... 3

A

IM OF THE RESEARCH

... 5

M

ETHODOLOGY

... 6

CHAPTER - II: BULK HYDROPHOBIC TREATMENT OF CEMENTITIOUS MATERIAL .. 9

C

EMENT

... 10

II.1.1. Classification of cement ... 11

C

EMENT PASTE AND MORTAR

... 12

II.2.1. Cement hydration ... 13

C3S - tricalcium silicate (3CaO.SiO2)... 13

C2S – dicalcium silicate (2CaO.SiO2) ... 14

C3A – calcium aluminate (3CaO.Al2O3) ... 14

C4AF – calcium alumoferrite (4CaO.Al2O3.Fe2O3) ... 15

II.2.2. Cement hydration ... 16

Stage I – Initial hydration ... 17

Stage II – Dormant phase (low hydration reactions) ... 18

Stage III – Acceleration phase ... 18

Stage IV – Deceleration phase ... 19

Stage V – Curing ... 19

II.2.3. Cement particles interaction during early age hydration – cohesion ... 20

II.2.3.1. Electric double-layer forces ... 20

II.2.3.2. Rheology of cement paste ... 20

II.2.4. Setting and hardening ... 21

C

HEMISTRY OF SILANES AND SILOXANES

.

I

NTERACTION WITH CEMENT

... 22

II.3.1. Silanes and siloxanes ... 22

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iv

II.3.3. Silane admixture... 24

H

YDROPHOBIC TREATMENT OF CEMENTITIOUS MATERIALS

... 24

II.4.1. Reaction of silanes with cement ... 26

II.4.1.1. Surface protection ... 28

II.4.1.2. Silanes as integral water repellents in cementitious materials ... 30

II.4.1.3. Influence of bulk hydrophobic treatment on the functional properties of mortars ... 31

II.4.2. Microencapsulation as a method for the delayed release ... 33

II.4.2.1. Silica dissolution in cement paste ... 34

CHAPTER - III: METHODS AND RAW MATERIALS CHARACTERIZATION ... 35

M

ATERIALS

... 36

III.1.1. CEM I and CEM III ... 36

III.1.2. Presentation of the admixtures used as integral water repellents ... 37

M

IXING PROPORTIONS

... 38

III.2.1. Mixing procedure and curing conditions for cement pastes ... 39

III.2.2. Mixing procedure of mortars and curing conditions ... 40

C

HARACTERIZATION METHODS

... 40

III.3.1. Characterization of the cement paste and admixtures ... 40

III.3.1.1. Phase analysis - X-ray diffraction (XRD/Rietveld analysis) ... 40

III.3.1.2. X-ray Fluorescence (XRF) ... 41

III.3.1.3. Microstructure investigation – Scanning Electron Microscopy (SEM) and Environmental Scanning electron microscopy (ESEM) ... 41

III.3.1.4. Mercury intrusion porosimetry (MIP) ... 42

III.3.1.5. Differential-Scanning Calorimetry with Thermo-Gravimetric Analysis (DSC-TGA) ... 42

III.3.1.6. Isothermal conduction calorimetry (TAM-Air) ... 43

III.3.1.7. Setting time... 43

III.3.1.8. Fourier transformation infrared spectroscopy (FTIR) ... 43

III.3.1.9. Laser granulometry – (Mastersizer) ... 44

III.3.1.10. Electrical resistivity of the liquid ... 44

III.3.1.11. Inductive coupled plasma-optical emission spectrometry (ICP-OES) ... 45

III.3.1.12. Surface tension ... 45

III.3.1.12.1. Pendant drop method ... 45

III.3.1.12.2. Dip ring method (Du Noüy) ... 45

III.3.2. Characterization of mortars ... 45

III.3.2.1. Penetration resistance test ASTM C403 ... 45

III.3.2.2. Evolution of mechanical properties ... 46

III.3.2.2.1. Ultrasonic Pulse Velocity (UPV) ... 46

III.3.2.2.2. Standard compression test on cubes (10 cm side) ... 48

III.3.2.3. Electrical conductivity [152] (ConSensor) ... 48

III.3.2.4. Autogenous deformation (AutoShrink) ... 49

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III.4.1. Cement ... 52

III.4.2. FTIR ... 53

III.4.3. ESEM of the microcapsules ... 55

III.4.4. Particle size distribution of the microcapsules ... 56

III.4.5. Thermal analysis of the admixtures (DSC-TGA)... 57

CHAPTER - IV: FUNDAMENTAL STUDY ON THE MICROCAPSULES STABILITY IN

ALKALINE SOLUTION ... 59

I

NTRODUCTION

... 60

R

ESULTS

... 61

IV.2.1. FTIR of additives in alkaline solution ... 61

IV.2.2. Influence on the surface tension ... 62

IV.2.2.1. Filtrated suspension ... 62

IV.2.2.2. Non-filtrated suspension ... 63

IV.2.2.3. Dip ring method (Du Noüy) ... 64

IV.2.3. Electrical conductivity... 65

IV.2.3.1. Kinetics of the shell dissolution in calcium hydroxide ... 68

IV.2.4. Influence of cations (Ca2+_{, Na}+_{) on the shell reaction mechanism ... 70}

IV.2.4.1. Microcapsules in lime solution ... 71

IV.2.4.2. Microcapsules in NaOH ... 72

IV.2.5. XRF and XRD of the flocs after 24h in lime solution ... 73

IV.2.5.1. FTIR analysis of the reaction products of microcapsules in NaOH ... 74

IV.2.5.2. FTIR of the flocs from limeM vs. resin from sodM ... 75

IV.2.6. What is the influence of Ca2+_{cation on the resin release at high pH? ... 76}

IV.2.6.1. Low temperature DSC of flocculated microcapsules in lime solution ... 77

A

MODEL OF THE SHELL DISSOLUTION AND THE MECHANISM OF THE RESIN RELEASE

... 79

S

UMMARY

... 82

CHAPTER - V: CEMENT HYDRATION IN PRESENCE OF SILANES. INFLUENCE ON THE

MICROSTRUCTURE DEVELOPMENT ... 85

I

NTRODUCTION

... 86

E

ARLY AGE CEMENT HYDRATION

... 86

V.2.1. Cohesion of cement ... 87

V.2.1.1. Rheology ... 87

V.2.2. Setting time ... 91

V.2.3. Hydration kinetics ... 93

V.2.4. Pore solution composition followed by the ICP-OES ... 96

V.2.5. Cement hydration at very early age (first hour) followed by ESEM ... 101

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vi

V.3.1. Thermal analysis of cement pastes (DSC-TGA) ... 108

V.3.2. Portlandite content from TGA measurements ... 112

V.3.2.1. Porosity and pore sizes distribution ... 113

V.3.2.2. Phase composition – XRD ... 115

V.3.2.3. SEM-EDX observation on cement pastes ... 119

V.3.2.4. FTIR of cement pastes ... 125

S

UMMARY

... 128

CHAPTER - VI: INFLUENCE OF BULK HYDROPHOBIC TREATMENT ON

THERMO-CHEMO-MECHANICAL PROPERTIES OF MORTARS ... 131

I

NTRODUCTION

... 132

M

ETHODOLOGY

... 132

VI.2.1. Equivalent age ... 136

R

ESULTS

... 137

VI.3.1. Hydration kinetics ... 137

VI.3.2. Influence of the admixtures on the setting time... 139

VI.3.3. Influence of the bulk hydrophobic treatment on the evolution of early age mechanical properties of mortars ... 140

VI.3.3.1. Compressive strength evolution by ConSensor ... 140

VI.3.4. Continuous monitoring of the early age hardening of mortars with integral water repellents 143 VI.3.4.1. Evolution of dynamic E- modulus (Edyn) and Poisson’s ratio (νdyn) ... 144

iii Table of contents

iii

Table of contents

:

ACKNOWLEDGEMENTS ... I

TABLE OF CONTENTS ... III

LIST OF TABLES ... VII

LIST OF FIGURES ... IX

ABSTRACT ... XVII

RÉSUMÉ ... XVIII

TABLE OF ACRONYMS AND ABBREVIATIONS ... XX

PUBLICATION LIST ... XXI

CHAPTER - I: INTRODUCTION ... 1

G

... 2

M

... 3

A

... 5

M

... 6

CHAPTER - II: BULK HYDROPHOBIC TREATMENT OF CEMENTITIOUS MATERIAL .. 9

C

... 10

C

... 12

C

.

I

... 22

iv

H

... 24

CHAPTER - III: METHODS AND RAW MATERIALS CHARACTERIZATION ... 35

M

... 36

M

... 38

C

... 40

v

CHAPTER - IV: FUNDAMENTAL STUDY ON THE MICROCAPSULES STABILITY IN

ALKALINE SOLUTION ... 59

I

... 60

R

... 61

A

... 79

S

... 82

CHAPTER - V: CEMENT HYDRATION IN PRESENCE OF SILANES. INFLUENCE ON THE

MICROSTRUCTURE DEVELOPMENT ... 85

I

... 86

E

... 86

vi

S

... 128

CHAPTER - VI: INFLUENCE OF BULK HYDROPHOBIC TREATMENT ON

THERMO-CHEMO-MECHANICAL PROPERTIES OF MORTARS ... 131

I

... 132

M

... 132

R

... 137

S

... 150

CHAPTER - VII: GENERAL CONCLUSIONS AND PERSPECTIVES ... 153

G

... 154

P

... 159

ANNEX 1. EFFECTIVENESS OF THE MICROCAPSULES AS AN INTEGRAL WATER

REPELLENT ... 161

ANNEX 2. HYDROPHOBICITY OF CEMENT PASTES CURED FOR 1 DAY ... 161

ANNEX 3 PARTICLE SIZES DISTRIBUTION OF ANHYDROUS CEMENT ... 163

ANNEX 4 CRYSTALLOGRAPHIC STRUCTURE OF HYDRATED CEMENT ... 164