Pumping is the most efficient transportation and placing method for concrete. Despite the immense progress in the field of concrete technology in the last years, so far there are still neither official regulations nor verified theoretical foundations to be used for the assessment and accurate prediction pumping behaviour of ordinary and high performance concretes. This thesis aims at purposefully investigating pumping of modern concretes and bridging the existing knowledge gap. The main achievement of the present research is the development and verification of a sitecompliant and scientifically based methodology for characterisation and prediction of fresh concrete pumping behaviour. The research focus is set on the importance of the forming lubricating layer (LL) during pumping. Within an extended experimental program, the properties of the LL are captured and quantified. They determine the reduction of friction at the pipe wallconcrete interface and thereby govern the concrete flow. It is proven that the composition and the rheological properties of the forming LL exert an enormous impact on pumping since most of the induced shear stress by pumping pressure is concentrated in this layer.
In a further step, the flow pattern of concrete is analytically and numerically determined. The concrete exhibits various principal flow types which are already defined at low flow rates: plug flow in case of strainhardening cementbased composite (SHCC), partial concrete bulk shear in ordinary concretes and pronounced bulk shear for selfcompacting concrete (SCC). The results from the fullscale pumping campaign are confronted with the existing pressure performance nomogram on the determination of pumping parameters. The nomogram’s prediction capacity is extended and verified for highly flowable concretes by replacing the slump and flow table results with the viscosity parameter of the LL. Furthermore, the challenges during pumping of concrete, inter alia, priming of the pipeline, blockage formation and final cleaning, are exemplified, and recommendations for the practitioners are provided.
Finally, the transfer of the developed scientifically based and ready to use methodology on site is strongly advocated as a part of the future in situ rheology monitoring concept towards envisaged full automation of concrete production and casting processes.:ZUSAMMENFASSUNG V
ABSTRACT VII
VORWORT DES HERAUSGEBERS IX
DANKSAGUNG XI
SYMBOLS XVII
INTRODUCTION 1
1.1 FLASHLIGHTS ON HISTORY 1
1.2 MOTIVATION 1
1.3 RESEARCH FIELD 3
1.4 RESEARCH CONCEPT 6
1.5 ECONOMIC RELEVANCE 8
1.6 STRUCTURE AND BOUNDARIES OF THE THESIS 10
STATE OF THE ART 13
2.1 GENERAL 13
2.2 CONCRETE FLOW IN PIPELINE 13
2.3 INFLUENCE OF CONCRETE RHEOLOGY ON PUMPING BEHAVIOUR 16
2.3.1 CEMENT HYDRATION 16
2.3.2 MIXTURE COMPOSITION 17
2.3.2.1 WATER-TO-BINDER RATIO AND PASTE VOLUME 18
2.3.2.2 AGGREGATES 20
2.3.2.3 ADMIXTURES AS PUMPING AIDS 22
2.3.3 HYDRODYNAMIC INTERACTIONS 25
2.3.4 SHEAR HISTORY 27
2.3.5 TEMPERATURE 28
2.4 FORMATION OF LUBRICATING LAYER 30
2.4.1 FLOW-INDUCED PARTICLE MIGRATION 30
2.4.2 PROPERTIES 31
2.4.3 EXPERIMENTAL CHARACTERISATION 32
2.5 BOUNDARY CONDITIONS 32
2.6 PUMPING EQUIPMENT 34
2.7 PRIMING 35
3 APPLIED METHODS 37
3.1 GENERAL 37
3.2 RHEOMETRY 37
3.3 DIRECT DETERMINATION OF PUMPING PRESSURE 40
3.4 SAMPLING AND PRODUCTION OF LUBRICATING MATERIAL 42
3.5 MEASUREMENT OF FILTRATE AMOUNT 45
3.6 ANALYTICAL DETERMINATION OF LUBRICATING LAYER THICKNESS 47
3.7 SMALL-SCALE PUMPING 49
3.8 FULL-SCALE PUMPING 50
3.9 NUMERICAL METHOD 56
3.9.1 MATERIAL MODEL 56
3.9.2 NUMERICAL IMPLEMENTATION 58
4 CHARACTERISATION OF CONCRETE PUMPABILITY 63
4.1 GENERAL 63
4.2 MIXTURE DESIGN PARAMETERS 63
4.3 COMPARISON BETWEEN REFERENCE AND DESIGN MORTARS 65
4.4 RESULTS AND DISCUSSION 65
4.4.1 RHEOLOGICAL BEHAVIOUR OF CONCRETES AND DESIGN MORTARS 65
4.4.2 INFLUENCE OF WALL ROUGHNESS ON RHEOLOGICAL PARAMETERS 67
4.4.3 PREDICTION OF PUMPING PRESSURE 72
4.5 SUMMARY 74
5 LUBRICATING LAYER THICKNESS AND CONCRETE FLOW 75
5.1 GENERAL 75
5.2 MIXTURE DESIGN PARAMETERS 75
5.3 RESULTS AND DISCUSSION 76
5.3.1 CONCRETE FLOW TYPE 76
5.3.2 PREDICTION AND VERIFICATION OF PUMPING PRESSURE 77
5.3.3 QUANTIFICATION OF LUBRICATING LAYER THICKNESS 79
5.4 SUMMARY 82
6 FULL-SCALE PUMPING EXPERIMENTS 83
6.1 GENERAL 83
6.2 MIXTURES AND DESIGN PARAMETERS 83
6.3 RESULTS AND DISCUSSION 85
6.3.1 PRESSURE LOSS AND PRESSURE-FLOW RATE CURVES 85
6.3.2 NUMERICAL SIMULATION RESULTS 86
6.3.3 PRESSURE PREDICTION USING MODIFIED NOMOGRAM 88
6.3.4 COMPARISON BETWEEN PREDICTED AND ACTUAL PRESSURE-FLOW RATE CURVES 90
6.4 SUMMARY 92
7 EFFECT OF PUMPING ON FRESH PROPERTIES OF CONCRETE AND FILTRATE FORMATION 95
7.1 GENERAL 95
7.2 MIXTURES DESIGN PARAMETERS 95
7.3 INFLUENCE OF PUMPING ON PROPERTIES OF FRESH CONCRETE 97
7.4 INFLUENCE OF CONCRETE PROPERTIES ON KINETICS OF FILTRATE FORMATION 98
7.5 IMPACT OF FILTRATE AMOUNT ON PUMPABILITY 101
7.6 SUMMARY 104
8 CHALLENGES RELATED TO PUMPING OF CONCRETE 105
8.1 GENERAL 105
8.2 PRIMING GROUT 105
8.3 PIPELINE GEOMETRY 108
8.4 BLOCKAGES 113
8.5 FILLING DEGREE OF PUMP PISTONS 116
8.6 TEMPERATURE CONTROL 117
8.7 VERTICAL PUMPING 118
8.8 CLEANING THE PIPELINE 119
8.9 SUMMARY 120
9 FINAL CONCLUSIONS AND OUTLOOK 121
9.1 GENERAL 121
9.2 CONCRETE FLOW TYPE 121
9.3 LUBRICATING LAYER PROPERTIES 121
9.4 RHEOLOGICAL DEVICES 122
9.5 FILTRATE FORMATION 122
9.6 NUMERICAL SIMULATIONS 122
9.7 MODIFIED NOMOGRAM 123
9.8 RELEVANCE OF PUMPING EXPERIMENTS 123
9.9 INFLUENCE OF PUMPING ON FRESH CONCRETE PROPERTIES 124
9.10 GENERATED DATABASE 124
9.11 IMPROVING NUMERICAL MODEL 124
9.12 TODAY AND TOMORROW 124
BIBLIOGRAPHY 127
APPENDIX A 135
A.1 MATERIALS DESCRIPTION, CHAPTERS 4 AND 5 135
A.2 MATERIALS DESCRIPTION, CHAPTERS 6, 7 AND 8 136
APPENDIX B 137
APPENDIX C 141
LIST OF SELECTED PUBLICATIONS 143
JOURNALS 143
CONFERENCE PAPERS 143
CURRICULUM VITAE 145 / Das Pumpen stellt die effektivste Methode für das Fördern und Einbringen von Frischbeton auf der Baustelle dar. Trotz der in den letzten Jahren erreichten deutlichen Fortschritte auf betontechnologischem Gebiet existieren für die Beurteilung der Pumpbarkeit von Beton bisher weder offiziell gültige Vorschriften noch abgesicherte theoretische Grundlagen, die eine zielsichere Vorhersage des Pumpverhaltens von Normal- als auch Hochleistungsbetonen ermöglichen. Die vorliegende Arbeit schließt entsprechende Wissenslücken und befasst sich gezielt mit dem Pumpen moderner Betone. Grundlegenden Erkenntnisgewinn stellt die Entwicklung einer wissenschaftlich fundierten, baustellengerechten Prüfmethodik zur Charakterisierung und Vorhersage des Pumpverhaltens von Frischbeton dar. Der Untersuchungsfokus richtet sich auf die Wirkung der sich beim Pumpvorgang ausbildenden Gleitschicht. Ein umfangreiches Untersuchungsprogramm gestattet die Erfassung und Quantifizierung der Eigenschaften dieser Schicht. Sie bestimmen infolge deutlicher Reduzierung der Reibung an der Grenzfläche zwischen Rohrwandung und Beton die Betonströmung entscheidend. Bewiesen wird, dass Betonzusammensetzung und rheologische Eigenschaften der Gleitschicht maßgebende Auswirkungen auf den Pumpvorgang haben, da sich die pumpdruckinduzierte Scherspannung in dieser Schicht konzentriert.
Weiterhin erfolgt sowohl eine analytische als auch numerische Charakterisierung der Betonströmung im Rohr. Nachgewiesen wird, dass sich beim Pumpvorgang betonspezifisch unterschiedliche Strömungsarten einstellen, die bereits bei niedrigen Durchflussmengen definiert sind: Pfropfenströmung in hochduktilen Betonen, partielle Scherung des Kernbetons in Normalbetonen und signifikante Scherung in selbstverdichtenden Betonen. Aus großtechnisch durchgeführten Pumpversuchen gewonnene Ergebnisse werden dem derzeit vorhandenen, verbesserungsbedürftigen Betondruck-Leistungs-Nomogramm zur Einstellung von Parametern an der Betonpumpe gegenübergestellt. Die Vorhersagekapazität des Nomogramms kann durch den Ersatz der Ausbreit- bzw. Setzfließmaßangaben mit Viskositätsangaben der Gleitschicht erweitert und verifiziert werden. Des Weiteren werden baustellenbezogene Herausforderungen im Gesamtprozess des Betonpumpvorgangs, u. a. Vorbereitung der Rohrleitung vor dem Pumpen, Auftreten von Stopfern und Endreinigung exemplarisch dargestellt sowie Empfehlungen für die Praktiker erarbeitet.
Schließlich wird der Transfer der in dieser Arbeit entwickelten wissenschaftlich basierten und anwendungsbereiten Methodik als Teil des zukünftigen Konzeptes für die in-situ Rheologie-Überwachung hinsichtlich einer angestrebten vollständigen Automatisierung von Fertigungs- und Einbringprozessen von Beton mit Nachdruck empfohlen.:ZUSAMMENFASSUNG V
ABSTRACT VII
VORWORT DES HERAUSGEBERS IX
DANKSAGUNG XI
SYMBOLS XVII
INTRODUCTION 1
1.1 FLASHLIGHTS ON HISTORY 1
1.2 MOTIVATION 1
1.3 RESEARCH FIELD 3
1.4 RESEARCH CONCEPT 6
1.5 ECONOMIC RELEVANCE 8
1.6 STRUCTURE AND BOUNDARIES OF THE THESIS 10
STATE OF THE ART 13
2.1 GENERAL 13
2.2 CONCRETE FLOW IN PIPELINE 13
2.3 INFLUENCE OF CONCRETE RHEOLOGY ON PUMPING BEHAVIOUR 16
2.3.1 CEMENT HYDRATION 16
2.3.2 MIXTURE COMPOSITION 17
2.3.2.1 WATER-TO-BINDER RATIO AND PASTE VOLUME 18
2.3.2.2 AGGREGATES 20
2.3.2.3 ADMIXTURES AS PUMPING AIDS 22
2.3.3 HYDRODYNAMIC INTERACTIONS 25
2.3.4 SHEAR HISTORY 27
2.3.5 TEMPERATURE 28
2.4 FORMATION OF LUBRICATING LAYER 30
2.4.1 FLOW-INDUCED PARTICLE MIGRATION 30
2.4.2 PROPERTIES 31
2.4.3 EXPERIMENTAL CHARACTERISATION 32
2.5 BOUNDARY CONDITIONS 32
2.6 PUMPING EQUIPMENT 34
2.7 PRIMING 35
3 APPLIED METHODS 37
3.1 GENERAL 37
3.2 RHEOMETRY 37
3.3 DIRECT DETERMINATION OF PUMPING PRESSURE 40
3.4 SAMPLING AND PRODUCTION OF LUBRICATING MATERIAL 42
3.5 MEASUREMENT OF FILTRATE AMOUNT 45
3.6 ANALYTICAL DETERMINATION OF LUBRICATING LAYER THICKNESS 47
3.7 SMALL-SCALE PUMPING 49
3.8 FULL-SCALE PUMPING 50
3.9 NUMERICAL METHOD 56
3.9.1 MATERIAL MODEL 56
3.9.2 NUMERICAL IMPLEMENTATION 58
4 CHARACTERISATION OF CONCRETE PUMPABILITY 63
4.1 GENERAL 63
4.2 MIXTURE DESIGN PARAMETERS 63
4.3 COMPARISON BETWEEN REFERENCE AND DESIGN MORTARS 65
4.4 RESULTS AND DISCUSSION 65
4.4.1 RHEOLOGICAL BEHAVIOUR OF CONCRETES AND DESIGN MORTARS 65
4.4.2 INFLUENCE OF WALL ROUGHNESS ON RHEOLOGICAL PARAMETERS 67
4.4.3 PREDICTION OF PUMPING PRESSURE 72
4.5 SUMMARY 74
5 LUBRICATING LAYER THICKNESS AND CONCRETE FLOW 75
5.1 GENERAL 75
5.2 MIXTURE DESIGN PARAMETERS 75
5.3 RESULTS AND DISCUSSION 76
5.3.1 CONCRETE FLOW TYPE 76
5.3.2 PREDICTION AND VERIFICATION OF PUMPING PRESSURE 77
5.3.3 QUANTIFICATION OF LUBRICATING LAYER THICKNESS 79
5.4 SUMMARY 82
6 FULL-SCALE PUMPING EXPERIMENTS 83
6.1 GENERAL 83
6.2 MIXTURES AND DESIGN PARAMETERS 83
6.3 RESULTS AND DISCUSSION 85
6.3.1 PRESSURE LOSS AND PRESSURE-FLOW RATE CURVES 85
6.3.2 NUMERICAL SIMULATION RESULTS 86
6.3.3 PRESSURE PREDICTION USING MODIFIED NOMOGRAM 88
6.3.4 COMPARISON BETWEEN PREDICTED AND ACTUAL PRESSURE-FLOW RATE CURVES 90
6.4 SUMMARY 92
7 EFFECT OF PUMPING ON FRESH PROPERTIES OF CONCRETE AND FILTRATE FORMATION 95
7.1 GENERAL 95
7.2 MIXTURES DESIGN PARAMETERS 95
7.3 INFLUENCE OF PUMPING ON PROPERTIES OF FRESH CONCRETE 97
7.4 INFLUENCE OF CONCRETE PROPERTIES ON KINETICS OF FILTRATE FORMATION 98
7.5 IMPACT OF FILTRATE AMOUNT ON PUMPABILITY 101
7.6 SUMMARY 104
8 CHALLENGES RELATED TO PUMPING OF CONCRETE 105
8.1 GENERAL 105
8.2 PRIMING GROUT 105
8.3 PIPELINE GEOMETRY 108
8.4 BLOCKAGES 113
8.5 FILLING DEGREE OF PUMP PISTONS 116
8.6 TEMPERATURE CONTROL 117
8.7 VERTICAL PUMPING 118
8.8 CLEANING THE PIPELINE 119
8.9 SUMMARY 120
9 FINAL CONCLUSIONS AND OUTLOOK 121
9.1 GENERAL 121
9.2 CONCRETE FLOW TYPE 121
9.3 LUBRICATING LAYER PROPERTIES 121
9.4 RHEOLOGICAL DEVICES 122
9.5 FILTRATE FORMATION 122
9.6 NUMERICAL SIMULATIONS 122
9.7 MODIFIED NOMOGRAM 123
9.8 RELEVANCE OF PUMPING EXPERIMENTS 123
9.9 INFLUENCE OF PUMPING ON FRESH CONCRETE PROPERTIES 124
9.10 GENERATED DATABASE 124
9.11 IMPROVING NUMERICAL MODEL 124
9.12 TODAY AND TOMORROW 124
BIBLIOGRAPHY 127
APPENDIX A 135
A.1 MATERIALS DESCRIPTION, CHAPTERS 4 AND 5 135
A.2 MATERIALS DESCRIPTION, CHAPTERS 6, 7 AND 8 136
APPENDIX B 137
APPENDIX C 141
LIST OF SELECTED PUBLICATIONS 143
JOURNALS 143
CONFERENCE PAPERS 143
CURRICULUM VITAE 145
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:30934 |
| Date | 24 April 2018 |
| Creators | Secrieru, Egor |
| Contributors | Mechtcherine, Viktor, De Schutter, Geert, Lohaus, Ludger, Technische Universität Dresden |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | doc-type:doctoralThesis, info:eu-repo/semantics/doctoralThesis, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | urn:nbn:de:bsz:14-qucosa-234594, qucosa:30907 |
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