Acknowledgements .............................................. iii
Notation ....................................................... ix
Abstract........................................................ xi
Graphic abstract .............................................. xii
1 Introduction ................................................. 1
1.1 Cement-based mortar ..................................... 1
1.2 Problems at construction sites .......................... 3
1.3 Research hypotheses and objectives ...................... 4
2 Background ................................................... 5
2.1 General ................................................. 5
2.2 Mixing and pumping processes ............................ 5
2.3 Particle dispersion in suspensions ...................... 8
2.3.1 General .......................................... 8
2.3.2 Physical dispersion .............................. 9
2.3.3 Chemical dispersion ............................. 11
2.3.4 Definition of fully dispersed state ............. 13
2.4 Rheology ............................................... 15
2.4.1 General ......................................... 15
2.4.2 Flow characteristics ............................ 15
2.4.3 Rheological models .............................. 17
2.4.4 Oscillatory measurement ......................... 18
2.4.5 Rheograph ....................................... 20
2.5 Hydration kinetics ..................................... 22
2.5.1 Early hydration of Portland cement .............. 22
2.5.2 Early hydration of tricalcium silicate .......... 24
2.5.3 Early hydration of tricalcium aluminate ......... 29
2.6 Early age dimensional stability ........................ 30
2.6.1 General ......................................... 30
2.6.2 Autogenous shrinkage ............................ 32
2.6.3 Drying shrinkage ................................ 33
2.6.4 Capillary pore pressure ......................... 34
3 Experimental work ........................................... 37
3.1 General ................................................ 37
3.2 Tests with different mixing energies at a field scale .. 37
3.3 Tests with different mixing energies at a laboratory
scale .................................................. 39
3.3.1 Materials and proportions ....................... 39
3.3.2 Mixing methods and mixing equipment ............. 41
3.4 Tests simulating different pumping energies at
a field scale .......................................... 42
3.5 Tests simulating different pumping energies at
a laboratory scale ..................................... 43
3.5.1 Pressurization test ............................. 43
3.5.2 Mixing test ..................................... 44
3.5.3 Sedimentation test .............................. 44
3.6 Testing Methods ........................................ 44
3.6.1 Mixing energy ................................... 44
3.6.2 Flow properties ................................. 45
3.6.3 Water-Powder ratio, aggregate and air contents .. 45
3.6.4 Rheometric properties ........................... 46
3.6.5 Particle size distribution ...................... 47
3.6.6 Setting time and compressive strength ........... 47
3.6.7 Hydration kinetics .............................. 48
3.6.8 Dimensional stability ........................... 48
3.6.9 Capillary pore pressure ......................... 50
3.6.10 Water loss ...................................... 50
3.6.11 Pore size distribution .......................... 51
3.6.12 Surface tension ................................. 51
3.6.13 Weight loss using TG/DTA ........................ 52
3.6.14 Total organic carbon ............................ 53
3.6.15 BET specific surface area ....................... 54
3.6.16 Energy dispersive X-ray detector - Scanning
electron microscopy ............................. 54
3.6.17 In-situXRD ...................................... 55
4 Results ..................................................... 56
4.1 Effects of mixing energies at a field scale ............ 56
4.2 Effects of mixing energies at a laboratory scale ....... 56
4.2.1 Mixing energy ................................... 56
4.2.2 Temperature, flow properties and air contents ... 58
4.2.3 Particle size distribution ...................... 61
4.2.4 Storage elastic modulus ......................... 62
4.2.5 Setting time and compressive strength ........... 64
4.2.6 Hydration kinetics .............................. 65
4.2.7 Dimensional stability ........................... 68
4.2.8 Capillary pore pressure ......................... 76
4.2.9 Water loss ...................................... 80
4.2.10 Pore size distribution .......................... 82
4.2.11 TOC, surface tension and BET specific surface
area ............................................ 83
4.2.12 Weight loss using TG/DTA ........................ 85
4.2.13 EDX-SEM ......................................... 87
4.2.14 In-situ XRD ..................................... 89
4.3 Effects of pumping energies at a field scale ........... 91
4.4 Effects of pumping energies at a laboratory scale ...... 92
4.4.1 Pressurization test ............................. 92
4.4.2 Mixing test ..................................... 93
4.4.3 Sedimentation test .............................. 94
5 Discussion .................................................. 96
5.1 Rheograph .............................................. 96
5.2 Early hydration ........................................ 99
5.2.1 Classical explanation of change in early
hydration ....................................... 99
5.2.2 Extended explanation of changes in early
hydration ...................................... 100
5.2.3 Experimental demonstration for the protective
superficial layers ............................. 103
5.3 Mechanisms for changes in fluidity .................... 105
5.4 Dimensional stability ................................. 107
5.4.1 Deformation under covered conditions ........... 107
5.4.2 Deformation under uncovered conditions ......... 110
5.4.3 Comparisons using various mortars .............. 114
5.5 In-situ X-ray diffraction ............................. 115
6 Conclusions and perspectives ............................... 118
6.1 Conclusions ........................................... 118
6.2 Perspectives .......................................... 120
7 Bibliography ............................................... 122
8 Appendix ................................................... 130
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