DOCTORAL THESIS
Improvements in test methodology and characterisation of long-term flexure behaviour of
fibre-reinforced concrete
by Aitor Llano Torre
Supervised by PhD. Pedro Serna Ros PhD. José Rocío Martí Vargas
València, Spain December 2022
Table of Content
Agradecimientos ... i
Abstract ... iii
Resumen ... v
Resum ... vii
Table of Content ... ix
List of Figures ... xiii
Glossary... xxi
Chapter 1. Introduction ... 1
1.1. General approach ... 1
1.2. Objectives ... 2
1.3. Structure ... 3
Chapter 2. State of the Art: Review and analysis ... 5
2.1. Fibre-reinforced concrete (FRC) ... 5
2.1.1. Concrete matrix composition ... 5
2.2. Mechanical properties ... 7
2.2.1. Characterisation ... 8
2.2.2. Long-term properties ... 9
2.3. Creep testing methodologies for cracked FRC review ... 14
2.3.1. Bibliometric study ... 14
2.3.2. Flexure creep ... 20
Table of Content
2.3.3. Tensile creep ... 38
2.3.4. Flexure creep test in panels... 43
Chapter 3. Starting Methodology ... 49
3.1. Equipment and creep frame construction ... 49
3.2. Creep test procedure ... 52
Chapter 4. Procedure and Methodological Improvements ... 55
4.1. Glossary review ... 55
4.2. Pre-cracking level (CMODp) ... 59
4.3. Creep index (Ic)... 68
4.4. Recovery capacity during the multi-phase creep test ... 78
4.4.1. Delayed CMOD recovery after the pre-cracking phase ... 79
4.4.2. Delayed CMOD recovery after the creep phase ... 81
4.5. Flexure boundary conditions and flexure load configuration ... 86
4.5.1. Supporting rollers design improvements ... 88
4.6. Creep phase loading process duration (tci) ... 89
4.6.1. Influence of the loading ratio on the instantaneous deformation ... 91
4.7. Short-term deformation definition (CMODci15’) ... 96
4.8. Multi-specimen setup ... 99
4.8.1. Flexure configuration ... 100
4.8.2. Specimen selection ... 101
4.8.3. Loading and unloading procedures ... 109
4.8.4. Upper elements dead load influence ... 111
Chapter 5. Creep Characterisation Improvements ... 117
5.1. Shrinkage flexure test ... 117
5.1.1. Specimen location: environmental and boundary conditions ... 119
5.1.2. Shrinkage consideration ... 120
5.1.3. Shrinkage experimental results ... 120
5.2. Influence of compressive creep in long-term flexure performance ... 122
5.2.1. Creep coefficient assessment ... 124
5.3. Neutral axis ... 127
5.3.1. Experimental program ... 131
5.3.2. Monotonic flexure test... 132
5.3.3. Long-term flexure test ... 135
5.4. Flexural creep database ... 141
5.4.1. Starting methodology database first proposal ... 141
5.4.2. Round-Robin Test results exchange datasheet ... 142
5.4.3. International flexure creep test database proposal ... 143
Chapter 6. Proposed Methodology ... 149
6.1. Creep test procedure ... 149
6.1.1. Pre-cracking phase procedure ... 150
6.1.2. Creep phase procedure ... 153
6.1.3. Post-creep phase procedure ... 162
6.2. Creep test report ... 163
Chapter 7. Conclusions and Future Research ... 167
7.1. Conclusions ... 167
7.1.1. The large number of available FRC creep methodologies ... 167
7.1.2. Significant improvements in flexure creep test procedure ... 168
7.1.3. Contributions to flexure long-term behaviour assessment ... 172
7.1.4. Proposed flexure methodology ... 174
7.2. Future research ... 175
Bibliography ... 177
Appendix A: Creep experimental programmes ... 197
Appendix B: WP1 creep experimental programme and results ... 199
B.1. FRC matrix characterisation tests results ... 200
B.2. Pre-cracking stage ... 201
B.3. Creep stage ... 202
B.4. Post-creep stage ... 204
Appendix C: NAE1 creep experimental programme and results ... 207
C.1. FRC matrix characterisation tests results ... 207
C.2. Pre-cracking stage ... 207
C.3. Creep stage ... 208
Appendix D: RRT creep experimental programme and results ... 211
Table of Content
D.1. FRC matrix characterisation tests results ... 212
D.2. Pre-cracking stage ... 213
D.3. Creep stage ... 214
D.4. Post-creep stage ... 218
Appendix E: WP2 creep experimental programme and results ... 221
E.1. FRC matrix characterisation tests results ... 222
E.2. Pre-cracking stage ... 222
E.3. Creep stage ... 224
E.4. Post-creep stage ... 227
Appendix F: OC2 creep experimental programme and results ... 229
F.1. FRC matrix characterisation tests results ... 230
F.2. Pre-cracking stage ... 231
F.3. Creep stage ... 232
F.3. Post-creep stage ... 234
Appendix G: NAE2 creep experimental programme and results ... 237
G.1. FRC matrix characterisation tests results ... 237
G.2. Pre-cracking stage ... 238
G.3. Creep stage ... 241
Appendix H: NAE3 creep experimental programme and results ... 247
H.1. FRC matrix characterisation tests results ... 248
H.2. Pre-cracking stage ... 248
H.3. Creep stage ... 250
List of Publications ... 255
