Concrete’s great vulnerability against impact demonstrates significant risks of injury for workers and occupants in all building types, especially existing concrete structures in which protection measures were not originally integrated. Beside the social and economic costs directly associated with impact accidents, the reconstruction or replacement of buildings damaged by impact negatively affects the environment and resources. In response to the increasing public concern for safety and sustainability, the DFG Research Training Group GRK 2250 is formed with the core aim to develop significant improvements in the impact resistance of existing concrete buildings by applying thin strengthening layers made of innovative mineral-bonded composites. The introduction of textile-based high-performance reinforcement is highly instrumental in realizing the required functions of thin mineral-bonded strengthening layers.
Novel impact-resistant 3D reinforcement is developed on the basis of the innovative 3D cellular weaving technology in this dissertation. Woven 3D cellular structures are characterized by outstanding and customizable mechanical characteristics, owning to the flexible incorporation of elements with different materials and geometries both in in-plane and out-of-plane directions. Based on a systematic and partly iterative development process, impact-resistant woven 3D cellular reinforcements containing impact-load-oriented elements and impact-appropriate material combination are successfully designed and optimized. On the one hand, a series of experiments are conducted to capture the working mechanism of woven 3D cellular structure in mineral-bonded composites loaded under impact, and to understand the effects of critical structure features. On the other hand, feasible weave patterns and effective technological solutions are worked out and implemented to enable a reliable and low-damage manufacturing process. Through a series of impact experiments, it can be strongly evidenced that the developed 3D cellular reinforcement pronouncedly enhances the load bearing capacity, ductility and energy dissipation of mineral-bonded composite undergoing impact, thus, remarkably enhances its impact resistance.
The development of impact-resistant woven 3D cellular reinforcements in this dissertation introduces a completely new and unique class of textile-based reinforcement for concrete, as well as mineral-bonded composites, with numerous benefits over the presently available reinforcing structures. A major advantage of the novel 3D cellular reinforcement is the capability to activate and exploit multiple energy dissipation mechanisms using both material and structure properties, through which remarkable impact resistance can be obtained. Thanks to a high degree of versatility and flexibility in material combination and structure design, in combination with a high degree of automation and flexibility of the weaving technology, impact-resistant woven 3D cellular reinforcement that is highly customized to specific impact scenarios can be produced with a significant time and cost efficiency. Furthermore, impact-resistant woven 3D cellular reinforcements possess an integral 3D architecture that ensures a high structure stability, allowing for a speedy casting process with a high placement-accuracy. On that basis, a reasonable production cost and a stable performance of designed functions can be obtained. The successful development of impact-resistant woven 3D cellular reinforcement essentially facilitates the successful creation of high-performance mineral-bonded strengthening layers, through the use of which the impact resistance of existing concrete structures, thus, their sustainable use, significantly enhances.:1 INTRODUCTION AND MOTIVATION 1
2 LITERATURE REVIEW 7
2.1 Fundamentals of concrete and reinforced concrete 7
2.1.1 Normal concrete 7
2.1.2 Structural concrete family 10
2.1.3 Steel reinforced concrete 11
2.1.4 Concrete and reinforced concrete under impact loading 14
2.1.5 Fiber-based reinforcing materials for concrete 18
2.1.6 Fiber reinforced concrete 21
2.1.7 Textile reinforced concrete 22
2.2 Two-dimensional textile concrete reinforcements 24
2.2.1 Welded metal wire mesh 24
2.2.2 Expanded metal mesh 25
2.2.3 Woven 2D reinforcing structures 25
2.2.4 Warp knitted 2D reinforcing structures 27
2.2.5 Stitched 2D reinforcing structures 28
2.2.6 Adhesively-bonded 2D reinforcing structures 29
2.2.7 Discussion of 2D reinforcing structures 30
2.3 Three-dimensional textile concrete reinforcements 33
2.3.1 Assembled 3D reinforcing structures 33
2.3.2 Woven 3D reinforcing structures 34
2.3.3 Warp knitted 3D reinforcing structures 35
2.3.4 Stitched 3D reinforcing structures 36
2.3.5 Adhesively-bonded 3D reinforcing structures 36
2.3.6 Discussion of available 3D reinforcing structures 36
2.4 Woven 3D cellular structures 37
2.5 Conclusion based on literature review 37
3 RESEARCH AIMS AND OBJECTIVES 39
4 PRELIMINARY INVESTIGATION INTO IMPACT BEHAVIOR OF MINERAL-BONDED COMPOSITE REINFORCED WITH WOVEN 3D CELLULAR STRUCTURE 41
4.1 Introduction 41
4.2 Materials under investigation 43
4.2.1 Reinforcement - Reference woven 3D cellular structure 3DWT Ref 43
4.2.2 Matrix - Fine-grained concrete Pagel TF10 44
4.2.3 Comparing reinforcement - Warp knitted 2D structure 2D BZT2 44
4.3 Specimen labeling 45
4.4 Methodology of small-scale plate impact test 46
4.4.1 Specimen preparation 46
4.4.2 Test setup 47
4.5 Preliminary small-scale plate impact test results 47
4.6 Summary and conclusion of preliminary investigation 58
4.7 Derivation of requirements and procedure for developing impact-resistant woven 3D cellular reinforcement 59
5 DEVELOPMENT OF STRUCTURE SYSTEMATICS FOR IMPACT-RESISTANT WOVEN 3D CELLULAR REINFORCEMENT 63
5.1 Fundamentals of woven 3D cellular structure 64
5.1.1 Conventional woven structure 64
5.1.2 Elements of woven 3D cellular structure 65
5.1.3 Formation principles of woven 3D cellular structure 66
5.1.4 Variation possibilities within woven 3D cellular structure 68
5.2 Design concept of mineral-bonded strengthening layers against impact 71
5.3 Requirements for impact-resistant woven 3D cellular reinforcement 73
5.4 Two-plane woven 3D cellular reinforcements 77
5.4.1 Two-plane woven 3D cellular reinforcements with biaxial grids 77
5.4.2 Two-plane woven 3D cellular reinforcements with triaxial grids 81
5.4.3 Two-plane woven 3D cellular reinforcements with quadriaxial grids 82
5.5 Three-plane 3D cellular reinforcements 83
5.6 Material variation 85
5.6.1 Double yarns 85
5.6.2 Hybrid yarns 86
5.7 Selected impact-resistant woven 3D cellular reinforcements for realization and investigation 86
6 DEVELOPMENT OF WEAVE PATTERN FOR IMPACT-RESISTANT WOVEN 3D CELLULAR REINFORCEMENT 89
6.1 Introduction 89
6.2 Two-plane reference structure 3DWT Ref 90
6.3 Two-plane double yarn structure 3DWT DbWi 92
6.4 Three-plane structure 3DWT DbLyr 93
6.5 Two-plane pyramid structure 3DWT Pyr 95
7 DEVELOPMENT OF TECHNOLOGICAL SOLUTIONS FOR THE MANUFACTURE OF IMPACT-RESISTANT WOVEN 3D CELLULAR REINFORCEMENT 101
7.1 3D cellular weaving technology 101
7.2 Manufacture of two-plane double yarn structure 3DWT-DbWi 107
7.3 Manufacture of three-plane structure 3DWT-DbLyr 108
7.4 Manufacture of two-plane pyramid structure 3DWT-Pyr 112
8 TENSILE BEHAVIOR OF SHCC CONTAINING IMPACT-RESISTANT WOVEN 3D CELLULAR REINFORCEMENT 117
8.1 Quasi-static tension tests 117
8.1.1 Specimen preparation 117
8.1.2 Test setup 118
8.1.3 Quasi-static tension test results 119
8.2 High-speed tension tests 126
8.2.1 Specimen preparation 126
8.2.2 Test setup 126
8.2.3 High-speed tension test results 127
9 ENHANCEMENT OF IMPACT-RESISTANT WOVEN 3D CELLULAR REINFORCEMENT 131
9.1 Concept of enhanced impact-resistant 3D cellular reinforcement 131
9.2 Weave pattern development of enhanced impact-resistant reinforcement 3DWT Pyr Hyb 134
9.3 Manufacture of enhanced impact-resistant reinforcement 3DWT Pyr Hyb 136
9.3.1 Material selection 136
9.3.2 Carbon rovings impregnation 142
9.3.3 Steel wires straightening and preshaping 142
9.3.4 Weaving and realized structure 143
10 PERFORMANCE OF MINERAL-BONDED STRENGTHENING LAYER WITH IMPACT-RESISTANT WOVEN 3D CELLULAR REINFORCEMENT 147
10.1 Tensile behavior of SHCC reinforced with 3DWT Pyr Hyb 147
10.1.1 Specimen preparation 147
10.1.2 Quasi-static tension test results 148
10.1.3 Dynamic tension test results 154
10.2 Impact behavior of SHCC reinforced with 3DWT Pyr Hyb 157
10.2.1 Materials under investigation 157
10.2.2 Small-scale plate impact test results 159
10.3 SHCC reinforced with 3DWT Pyr Hyb as strengthening layer on the impacted side of concrete core 169
10.4 Summary and conclusion of the performance investigation on mineral-bonded strengthening layer reinforced with 3DWT Pyr Hyb 173
11 CONCLUSIONS AND RECOMMENDATIONS 175
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:92528 |
| Date | 18 July 2024 |
| Creators | Võ, Duy Minh Phương |
| Contributors | Cherif, Chokri, Boussu, François, Technische Universität Dresden |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, doc-type:doctoralThesis, info:eu-repo/semantics/doctoralThesis, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | info:eu-repo/grantAgreement/Deutsche Forschungsgemeinschaft/GRK 2250 - Mineral-bonded composites for enhanced structural impact safety/287321140//A1/I Development and evaluation of 3D reinforcing structures for structural strengthening against impact loading |
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