lHigh Performance Fiber Reinf orced

Cement Composites 2 (HPFRCC2)

Proceedings of the Second International Workshop 'High Performance Fiber Reinforced Cement Composites'

Sponsored by RILEM, ACI, ACBM, the University of Michigan and the University of Stuttgart.

Ann Arbor, USA June 11-14, 1995

EDITED BY

A.E. Naaman Department of Civil and Environmental Engineering,

The University of Michigan Ann Arbor, Michigan, USA

AND

H.W. Reinhardt Institut für Werkstoffe im Bauwesen,

University of Stuttgart, Gennany

E & FN SPON m. An lmprint of Chapman & Hall London · Glasgow · Weinheim · New York · Tokyo · Melbourne · Madras

Contents

Preface XV Workshop xvii Acknowledgments xix

1 Characterization of high performance fiber reinforced cement composites HPFRCC A.E Naaman and H. W. Reinhardt 1.1 Relative meaning of "advanced" and/or "high performance" Q 1.2 Definition and applications of high performance fiber reinforced

cement composites - HPFRCC 3 l.3 Conditions to achieve quasi-strain hardening and multiple cracking 3

1.3.1 Solution based on mechanics of composite materials 1.3.2 Solution based on micro-mechanics of crack bridging and

fracture l.3.3 Solution based on fracture energy of debonding

1.4 Comparison of critical fiber volume fraction 14 1.5 Minimum volume fraction of fibers 17 1.6 Toughness and fracture energy 17

1.6.l Toughness index 1.6.2 Fracture energy and energy of pull-out

1.7 Additional needs for characterization 21 1.8 Concluding remarks 22 1.9 Acknowledgments 22 1.10 References 23

2 Specific production and manufacturing issues 25 M. Cheyrezy, J.I. Daniel, H. Krenchel, H. Mihashi, J. Pera, P. Rossi and Y. Xi 2.1 Introduction 26 2.2 Matrices 27 2.3 Fibers 27 2.4 HPFRFCC reinforced with non-metallic fibers 28

2.4.1 Asbestos cement 2.4.2 Cellulose-pulp cements 2.4.3 Polypropylene cements 2.4.4 Carbon-mat-mortar composites (CMMC) 2.4.5 Glass-fiber reinforced composite (GFRC)

2.5 HPFRCCs reinforced with steel fibers 32 2.5.1 Reactive powder concrete (RPC) 2.5.2 LCPCs multifiber HPFRCCs 2.5.3 Compact reinforced composite (CRC) 2.5.4 Fiber reinforced chemically activated fly ash (FR-CAF A)

vi Contents

2.6 Manufacturing of HPFRCCs reinforced with non-metallic fibers 38 2.6.1 General 2.6.2 Mixing equipment and procedures 2.6.3 Placement 2.6.4 Curing

2.7 Manufacturing of HPFRCCs reinforced with metallic fibers 39 2.7.1 Mixing equipment and procedures 2.7.2 Placement 2.7.3 Vibration 2.7.4 Demoulding 2.7.5 Curing 2.7.6 Heat treatment

2.8 Conclusions 41 2.9 References 42

3 Micromecbanical models of mechanical response of HPFRCC 43 V.C. Li, H. Mihashi, H.C Wu, J.M. Alwan, A. Brincker, H. Horii, C.K. Y. Leung, M. Maalej and H. Stang 3.1 Introduction 44 3.2 Uniaxial tensile response 45

3.2.1 Introduction 3.2.2 Behavior before first cracking 3.2.3 The steady state cracking criterion -3.2.4 Condition for further cracking 3.2.5 Multiple cracking regirne 3.2.6 Effect of interfacial dual slip on multiple cracking 3.2.7 Tensile behavior of HPFRCC with main reinforcements 3.2.8 Effect of fiber weaving structure on tensile behavior of

HPFRCC 3.2.9 Conclusions

3.3 Uniaxial compressive response 59 3.3.1 Introduction 3.3.2 A micromechanical model 3.3.3 Combined strengthening and weakening effect of fiber addition 3.3.4 Further discussions and conclusions

3.4 Flexural response 66 3.4.1 Introduction 3.4.2 Flexural strength of quasi-brittle FRCC 3.4.3 Flexural strength of strain-hardening FRCC 3.4.4 Conclusion

3.5 Fracture response 75 3.5.1 Introduction 3.5.2 Discontinuous-aligned-fiber composites 3.5.3 Discontinuous-randomly-distributed-fiber composites 3.5.4 Strain hardening cementitious composites 3.5.5 Conclusions

3.6 Elastic modulus 85 3.6.1 Introduction

Contents vii

3.6.2 Pseudo three phase model 3.6.3 Homogenization based model 3.6.4 Conclusions

3.7 Discussions and conclusions 3.8 References

4 Cyclic behavior, fatigue strength, endurance limit and models for

93 96

fatigue behavior of FRC 101 V. Ramakrishnan, C. Meyer, A.E. Naaman, G. Zhao and L. Fang 4.1 Introduction 102 4.2 Flexural fatigue strength of FRC 103

4.2.1 Loading rate 4.2.2 Flexural fatigue investigations at a moderate frequency (20 Hz) 4.2.3 Flexural fatigue testing at low frequency

4.3 Flexural fatigue testing of slurry infiltrated fiber reinforced concrete (SIFCON) 117 4.3.l Tests done in USA 4.3.2 Tests done in China

4.4 Behavior of FRC under compressive cyclic loading 121 4.5 Models for fatigue strength and fatigue life prediction 130 4.6 Cyclic behavior and modeling 131

4.6.1 Cyclic behavior 4.6.2 Continuum damage mechanics based models 4.6.3 Models combining continuum damage mechanics and plasticity theory 4.6.4 Micromechanics models 4.6.5 Conclusions

4.7 References 143

S Fiber-matrix interfaces 149 A. Bentur, S.T. Wu, N. Banthia, R. Baggott, W. Hansen, A; Katz, C.K.Y. Leung, V.C. Li, B. Mobasher, A.E. Naaman, R. Robertson, P. Soroushian, H. Stang and L.R. Taerwe 5.1 Introduction 150 5.2 The microstructure of the interfacial transition zone 151

5.2.1 Macro-fibers 5.2.2 Micro-fibers 5.2.3 Bundled fibers

5.3 Failure and damage processes 156 5.4 Pull-out resistance and its modeling 158

5.4.1 Pull-out of aligned and straight fibers 5.4.2 Influence of lateral stresses and strains 5.4.3 Effect of fiber orientation 5.4.4 Effect of fiber bundling and multiple pull-out 5.4.5 Effects of pull-out rates and environmental temperature

5.5 Interfacial effects and stress transfer in fibers for high performance FRC 171 5.5.1 Enhancement of first crack strength

viii Contents

5.5.2 Strain hardening behavior 5.5.3 Bonding in micro-fibers 5.5.4 Bonding in macro-fibers of deformed shape 5.5.5 Bond enhancement by matrix modification 5.5.6 Durability

5.6 Conclusions 5. 7 References

183 185

6 Toughness characterization and toughening mechanisms 193 S.P. Shah, A.M. Brandt, C. Ouyang, R. Baggott, J. Eibl, M.A. Glinicki, H. Krenchel, A. Lambrechts, V.C. Li, B. Mobasher and L.R. Taerwe 6.1 Fracture process in cementitious materials 194 6.2 Toughening mechanisms in fiber reinforced composites 195 6.3 Characterization of interfacial behavior 199

6.4

6.5

6.6 6.7 6.8 6.9 6.10

6.3.1 Pullout of an aligned fiber 6.3.2 Pullout of an inclined fiber 6.3.3 Fracture of fibers Characterization of composite behavior 6.4.1 Fracture mechanics approach 6.4.2 Micromechanics approach Measurement of composite toughness 6.5.1 ASTM C 1018 method and its limitations 6.5.2 Methods based on fracture mechanics Influence of processing technique Design compressive strain softening curve The effect of loading rate Summary References

205

210

216 220 221 221 224

7 Computer models 229 J.M. Alwan, B. Mobasher, J.E. Bolander, C.K. Y. Leung, A.E. Naaman, D. V. Reddy, P. Rossi, P. Stroeven, M. Stroeven, J.G.M. van Mier and M.L. Wang 7.1 Introduction 230 7.2 Outline of chapter 231 7 3 Computer models at the constituent level 232

7.3.1 Tensile behavior of fiber reinforced cementitious composites 7.3.2 Fracture behavior of concrete 7.3 .3 Flexural behavior of fiber reinforced composite beams 7.3.4 Structural features of fiber reinforced cementitious composites 7.3.5 Fiber pullout from cementitious matrices 7.3.6 Crack growth in cementitious composites 7.3.7 Rigid particle modeling of FRC

7.4. Computer models at the engineering (large scale) level 269 7.4.1 Triaxial behavior of SIFCON 7.4.2 Endochronic constitutive modeling for analysis of marine fiber reinforced concrete

Contents ix

7.4.3 Structural response of fiber reinforced cement based beams 7.5. References 286

8 Reinforced and prestressed concrete using HPFRCC matrices 291 A.E. Naaman, P. Paramasivam, G. Balazs, Z. M. Bayasi, J. Eibl, L Erdelyi, N.M. Hassoun, N. Krstulovic-Opara, V.C. Li and G. Lohrmann 8.1 Introduction 292

8.1 .1 Classes of applications of HPFRCC 8.1.2 Some background with low end FRC composites 8.1 .3 Organization of this chapter

8.2 Crack width control in RC beams 295 8.2.l Introduction 8.2.2 Description and scope 8.2.3 Experiments 8.2.4 Results and discussion

8.3 Composite slabs using slurry infiltrated mat concrete - SIMCON 300 8.3.l Experimental program 8.3.2 Data analysis and test results 8.3.3 Conclusion

8.4 Repair and rehabilitation using slurry infiltrated mat concrete - SIMCON 304 8.4.1 Introduction 8.4.2 Experimental investigation 8.4.3 Analytical modeling 8.4.4 Conclusions

8.5 Plastic hinge in RC beam--column joint 308 8.5.1 Performance criteria 8.5.2 RJC beam--column connection 8.5.3 Results and discussions 8.5.4 Conclusions

8.6 Seismic joints for precast concrete frames 312 8.6.1 Description of framing system and test program 8.6.2 Main results

8.7 Plastic rotation and ductility index 315 8.7.l Experimental program

. 8.7.2 Presentation and discussion of test results 8.7.3 Conclusions

8.8 Over-reinforced RC beams using a slurry infiltrated fiber concrete (SIFCON) matrix 319

8.9 Effects of fibers on impact response of RC beams 321 8.9.l Preparation and test setup 8.9.2 Experimental results

8.10 Effects of fibers on shear response of RC and PC beams 326 8.10.l Introduction 8.10.2 Method based on plasticity analysis 8.10.3 Analytical models based on constitutive relations 8.10.4 Semi-empirical equation of ultimate strength 8.10.5 Results and conclusions

X Contents

8.11 Cyclic shear response of dowel reinforced slurry infiltrated fiber concrete - SIFCON 329 \ 8.11.1 Introduction and objectives 8.11.2 Results and conclusions

8.12 Behavior of prestressed SFRC under tension release 332 8.12.l lntroduction 8.12.2 Research significance 8.12.3 Experimental program 8.12.4 Test results with gradual tension release 8.12.5 Conclusions

8.13 Ductility of beams prestressed with fiber reinforced plastic tendons 338 8.14 Structural modeling 340

8.14.1 Nonlinear analysis and constitutive relations 8.14.2 Modeling of RC beams with a SIFCON matrix 8.14.3 Concluding remarks

8.15 Concluding remarks 342 8.16 Acknowledgments 343 8.17 References 344

9 Bond of reinforcing bars and prestressing tendons in HPFRCC matrices 349 P. Balaguru, P. G. Gambarova, G.P. Rosati and CE. Schumm 9.1 lntroduction 350 9.2 Experimental investigations 351

9.2.1 Deformed bars: monotonic loading 9.2.2 Deformed bars in confined fiber reinforced concrete (passive confinement) 9.2.3 Deformed bars in SIFCON 9.2.4 Deformed bars in micro fiber reinforced matrix 9.2.5 Deformed bars: cyclic loading 9.2.6 Pre-stressing tendons 9.2.7 Conclusions

9.3 Analytical modelling 375 9.3.l Nature of problem and previous literature 9.3.2 Proposed model 9.3.3 Applications 9.3.4 Conclusions

9.4 References 380

10 Standard testing 383 S. Mindess, L.R. Taerwe, Y.-Z. Lin, F. Ansari and G. Batson 10.l lntroduction 384 10.2 Strength tests 385 10.3 Toughness tests 386

10.3.1 Flexural toughness 10.3.2 Notched beam tests 10. 3. 3 Compressive toughness 10.3.4 Plate tests

Contents xi

10.4 Influence of size of test specimen 398 10.5 Type of testing machine 399 10.6 Instability in load-deflection curve 400 10.7 Effects of shear 402 10.8 Energy dissipation 402 10.9 Rate of loading effects 402 10.10 Fibre orientation 403

10.10.l Test prograrn 10.10.2 Data evaluation 10.10.3 Test results 10.10.4 Discussion of test results

10.11 Optical fibers for testing FRC 412 10.11.1 Fiber optic sensors in FRC 10.11.2 Fiber optic CTOD sensor 10.11.3 Experimental prograrn 10.11.4 Crack tip kinematics

10.12 Conclusions 416 10.13 References 416

11 Infrastructural repair and retrofit with HPFRCCs 423 N. Krstulovic-Opara and H. Toutanji 11.1 Introduction and background 424

11.1.1 Background on strain hardening and multiple cracking 11.1.2 Background on HPFRCC types used in R&R

11.2 Structural repair and retrofit 428 11.2.1 Repair 11.2.2 Retrofit

11.3 Durability repair and retrofit 431 11.3 .1 Background 11.3.2 Field use of HPFRCCs in repair and retrofit 11.3.3 Suggested guidelines

11.4 Conclusions 438 11.5 References 439

12 Practical structural applications of FRC and HPFRCC 443 J.G.M. van Mier, H. Stang and V. Ramakrishnan 12. l Introduction 444 12.2 Improving strength and toughness of materials and structures 445 12.3 Overview of new FRC and HPFRCC materials 447

12.3.1 Polyolefin fibre reinforced concrete 12.3.2 Reactive powder concrete 12.3.3 Compact reinforced composites 12.3.4 Slurry infiltrated fibre concrete

12.4 Development of FRC structural applications 452 12.5 Exarnples of PFRC applications 453 12.6 HPFRCC structural applications 453

12.6.1 Exarnples of CRC applications 12.6.2 Exarnples of RPC applications

xii Contents

12.6.3 Examples of SIFCON applications 12. 7 Conclusion , 457 12.8 References 457

13 Future research needs in the field of HPFRCC 461 H. W. Reinhardt, P. Rossi, R. Baggott, G. Balazs, J.E. Bolander, A.M. Brandt, M. Cheyrezy, K. Chong, L. Erdelyi, H. Krenchel, D. Lange, C.K.Y. Leung, V.C Li, H. Mihashi, A.E. Naaman, V.S. Parameswaran and H. Stang 13 .1 Introduction 462 13 .2 Mechanics 462

13.2.1 General 13 .2.2 Fundamental 13.2.3 Applied

13.3 Performance 464 13.4 Tailoring and production 465 13.5 Economy 465 13.6 Testing 466 13.7 Conclusion 466

14 Summary of presentations and discussions 469 H. Stang, G. König and P. Zia 14.1 Session 1: Characterization of high performance fiber reinforced

cement composites - HPFRCC 4 70 14.1.1 Presentation 14.1.2 Discussion

14.2 Session 2: Specific production and manufacturing issues 472 14.2.l Presentation 14.2.2 Discussion

14.3 Session 3: Micro-mechanical models of mechanical response of HPFRCC 474 14.3.l Presentation 14.3.2 Discussion

14.4 Session 4: Cyclic behavior, fatigue strength, endurance limit and models for fatigue behavior of FRC 475 14.4.l Presentation 14.4.2 Discussion

14.5 Session 5: Fiber-matrix interfaces 14. 5 .1 Presentation 14.5.2 Discussion

476

14.6 Session 6: Toughness characterization and toughening mechanism 477 14.6.l Presentation 14.6.2 Discussion

14.7 Session 7: Computer models 14. 7 .1 Presentation 14.7.2 Discussion

14.8 Session 8: Reinforced and prestressed concrete using HPFRCC

479

matrices 480

Contents xiii

14.9 Session 9: Bond ofreinforcing bars and prestressing tendons in HPFRCC matrices 481 14.9.1 Presentation 14.9.2 Discussion

14.10 Session 10: Standard testing 481 14.10.1 Presentation 14.10.2 Discussion

14.11 Session 11 : Infrastructural repair and retrofit with HPFRCCs 482 14 .11.1 Presentation 14.11.2 Discussion

14.12 Session 12: Practical structural applications ofFRC and HPFRCC 482 14.11.1 Presentation 14.11.2 Discussion

14.13 Session 13: Future research needs in the field ofHPFRCC 483 14.14 Keynote presentation on the role ofNSF and civil infrastructure

systems 483 14.15 Next workshop on HPFRCC 484

List of participants 485 Author index 493 Subject index 495