Slip Forming

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  • Slipforming of Vertical ConcreteStructures

    Friction between concrete and slipform panel

    by

    Kjell Tore Foss

    Dr.ing thesis

    Department of Structural EngineeringThe Norwegian University of Science and Technology

    N-7491 TrondheimNorway

    June 2001URN:NBN:no-1292

  • URN:NBN:no-1292

  • iii

    Acknowledgements

    I would like to express my gratitude to my main supervisor Professor Magne Maage for his personalcommitment, interesting discussions and valuable advice. Magne has been continuously encouragingand patient throughout my study. I will also express my gratitude to supervisor Sverre Smeplass forthe support and valuable advice throughout my study. Also the support and good advice fromsupervisor Malvin Sandvik is sincerely appreciated. Furthermore, special thanks to my colleagues atthe Department of Structural Engineering and especially to Erik Sellevold for interestingdiscussions.

    This work was made possible by the financial support from Aker Engineering AS, Selmer SkanskaAS, NCC Anlegg AS, Veidekke ASA, Norcem AS, Gleitbau Ges.m.b.H. and the Research Councilof Norway. The companies together with Norwegian Public Road Administration have beenrepresented in a reference group, which have followed the research program and given commentsand valuable advice throughout the execution of the research program.

    The experimental program has comprised planning and construction of test rigs and also a test panelfor installation in a slipform. Special thanks to T. Meltzer, J. Sandnes, J. Troset, . Langnes, B.Ingebrigtsen, O. Loraas, O. Haldorsen, K. Kristiansen, H. Rdsj and in particular S. Lorentzen forplanning and construction of these rigs and also for the assistance during execution of the tests.

    Furthermore, I am also grateful to S. Perlestenbakken and Interform AS for the opportunity to carryout field investigation during slipforming on site. This investigation went very well because of thesuccessfully cooperation and assistance from Interform AS during the test period on site.

    Special thanks to former Aker Norwegian Contractors (now a part of Aker Maritime ASA) forinitiating this research project. Without this initiative, this research project would not be started.Also a special thanks to the many conversations and interesting discussions with former and presentcolleagues in the company.

    I am also grateful to my family and friends for the support, encouragement and patience during thesefour years.

    Trondheim, June 2001

    Kjell T. Foss

    URN:NBN:no-1292

  • Table of contents

    Acknowledgements iii

    Table of contents iv

    Abstract x

    Notations xiii

    Definitions xv

    1 INTRODUCTION 1

    1.1 Background 1

    1.2 Principles of a slipform 1

    1.3 Differences between slipform and fixed formwork 3

    1.4 Objectives 3

    1.5 Scope of work 4

    2 LITERATURE REVIEW 5

    2.1 Introduction 5

    2.2 Fresh concrete properties 52.2.1 Introduction 52.2.2 Shear strength in concrete 72.2.3 Effective pressure 92.2.4 Pore water pressure 11

    2.2.4.1 General 112.2.4.2 Settlement and bleeding 122.2.4.3 Effect of hydration chemical shrinkage 122.2.4.4 Drying of surface 152.2.4.5 Break-through pressure 17

    2.2.5 Summary fresh concrete properties 19

    2.3 Lifting force and concrete pressure during slipforming 212.3.1 Introduction 212.3.2 Concrete in a slipform 212.3.3 Static and sliding friction 222.3.4 The slipforming rate 23

    URN:NBN:no-1292

  • v2.3.5 Concrete pressure on the panel 252.3.6 Effect of the concrete mix composition 282.3.7 Surface - slipform panel 292.3.8 Stress distribution during lifting 312.3.9 Surface defects 322.3.10 Summary lifting force and concrete pressure during slipforming 34

    2.4 Hardened properties 352.4.1 General 352.4.2 Compressive strength 362.4.3 Measurements of dynamic modulus of elasticity 392.4.4 Density of the concrete 402.4.5 Tensile splitting strength 422.4.6 Durability investigation carbonation measurements 432.4.7 Chloride diffusion coefficient 462.4.8 Summary hardened properties 47

    3 HYPOTHESES 49

    4 EXPERIMENTAL PROGRAM 52

    4.1 General 52

    4.2 Description of the test rigs 524.2.1 Friction rig 52

    4.2.1.1 Objectives 524.2.1.2 Reinforcement 534.2.1.3 Slipform panel 534.2.1.4 Pressure on top 534.2.1.5 The position measurements 544.2.1.6 Inductive displacement sensors 544.2.1.7 Pore water pressure gauge 544.2.1.8 Temperature measurements 554.2.1.9 Control and measurement system 55

    4.2.2 Vertical slipform rig 554.2.2.1 Objectives 554.2.2.2 Steel framework 564.2.2.3 Concrete container 564.2.2.4 Reinforcement 584.2.2.5 The slipform panel 584.2.2.6 Pressure lid on top 584.2.2.7 Normal force measurements 594.2.2.8 The position measurements 604.2.2.9 Inductive displacement sensor 604.2.2.10 Pore water pressure gauges 614.2.2.11 Temperature measurements 624.2.2.12 Control and measurement system 62

    4.2.3 Test panel used during field investigations 624.2.3.1 Design 62

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    4.2.3.2 Measurement gauges 634.2.3.3 Control and measurement system 64

    4.3 Concrete constituency 654.3.1 Introduction 654.3.2 Concrete mixes 65

    4.3.2.1 Friction rig 654.3.2.2 Vertical slipform rig 664.3.2.3 Field investigations 67

    4.3.3 Aggregate 684.3.4 Cement 704.3.5 Admixtures 70

    4.4 Test program 714.4.1 Friction rig 71

    4.4.1.1 Program 714.4.1.2 Execution method of the tests 73

    4.4.2 Vertical slipform rig 734.4.2.1 Program 734.4.2.2 Execution method of the single layer tests 754.4.2.3 3-layers concrete tests 75

    4.4.3 Field investigations 764.4.4 Testing on hardened concrete 76

    4.4.4.1 Capillary water absorption tests 76

    5 CALIBRATION AND VERIFICATION 78

    5.1 General 78

    5.2 Friction rig 785.2.1 Calibration of the measuring units 785.2.2 The slipform rig rate during movement 785.2.3 Control of the surface roughness 795.2.4 Sliding friction in the friction rig 815.2.5 Reproducibility test 82

    5.3 Vertical slipform rig 835.3.1 Calibration of the measuring units 835.3.2 Control of the spring steel 845.3.3 The rate of the slipform panel during lifting 845.3.4 Control of the surface roughness 855.3.5 Sliding friction in the vertical rig 855.3.6 Reproducibility test 86

    5.4 Test panel 90

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    6 METHOD OF EVALUATION AND PRESENTATION OF THEMEASUREMENTS 91

    6.1 Lifting force 91

    6.2 Effective pressure in the concrete 93

    6.3 The friction coefficient 956.3.1 Definitions of terms used to describe the pore water pressure development 98

    6.3.1.1 Pore water pressure decrease rate 986.3.1.2 Minimum pore water pressure 99

    7 RESULTS AND DISCUSSIONS 100

    7.1 Effective pressure 1007.1.1 Friction law 1007.1.2 The correlation between the net lifting stress and the effective pressure 1017.1.3 Statistical evaluation of the effective pressure 104

    7.1.3.1 Correlation between the effective pressure and the lifting stress 1047.1.4 The friction coefficient 105

    7.1.4.1 Concrete tests carried out on the vertical slipform rig 1057.1.4.2 Concrete tests carried out on the friction rig 107

    7.1.5 Observation during the regression analyses 1087.1.6 Summary 110

    7.2 The pressure in the pore water 1117.2.1 Introduction 1117.2.2 Particle concentration 113

    7.2.2.1 The effect of silica fume 1137.2.3 The effect of the air content 115

    7.2.3.1 Air entraining agents 1157.2.3.2 The effect of vibration 1167.2.3.3 The effect of lightweight aggregate 1187.2.3.4 The effect of the binder volume 120

    7.2.4 Water communication 1227.2.4.1 Water flow between concrete layers 1227.2.4.2 Surface drying 125

    7.2.5 The effect of normal pressure 1267.2.5.1 Correlation between minimum pore water pressure and normal pressure 129

    7.2.6 The effect of the slipform technical parameters 1307.2.7 Parameters affecting the minimum pore water pressure 1327.2.8 Summary 133

    7.3 The normal pressure 1367.3.1 Introduction 1367.3.2 The effect of the concrete density and the placing method 1367.3.3 The effect of the panel stiffness 1377.3.4 The effect of the inclination 1397.3.5 Summary 140

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    7.4 The impact of the material properties in the shear zone 1417.4.1 Introduction 1417.4.2 The lubricant properties 1417.4.3 Rough slipform panel 1437.4.4 Summary 146

    7.5 Operational parameters 1477.5.1 Introduction 1477.5.2 Lifting frequency 147

    7.5.2.1 Tests with normal weight concrete 1477.5.2.2 Tests with lightweight concrete 149

    7.5.3 The effect of the lifting height 1497.5.4 Calculation of the maximum lifting stress at different lifting heights 1517.5.5 Summary for the lifting height and the lifting frequency 1537.5.6 The effect of the lifting stress on the concrete surface 1547.5.7 One layer - several concrete layers 155

    7.5.7.1 Introduction 1557.5.7.2 Interaction between the concrete layers 1557.5.7.3 Verification procedure 1567.5.7.4 The same type of concrete in all layers 1587.5.7.5 Concrete with different properties 1607.5.7.6 With inclination of the slipform panel 162

    7.5.8 Summary several layers 165

    7.6 Field investigations 1667.6.1 Introduction 1667.6.2 Measured lifting stress and normal pressure during slipform operation 1667.6.3 Concrete tested in the slipform rig 1697.6.4 Surface quality 171

    7.6.4.1 Tukthus site 1717.6.4.2 Srkedalsv site 173

    7.6.5 Summary 174

    8 SUMMARY 176

    8.1 Objectives and Scope 176

    8.2 The friction law 176

    8.3 The pore water pressure 177

    8.4 Operational parameters 179

    8.5 Connection between lifting stress (friction) and surface damages 179

    8.6 The effect of combination of the parameters on the lifting stress 179

    8.7 Confirmation