Citation
Behavior of internally-cured high-performance concrete reinforced with glass fiber reinforced polymer bars

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Title:
Behavior of internally-cured high-performance concrete reinforced with glass fiber reinforced polymer bars
Creator:
Gao, Junhao
Place of Publication:
Denver, CO
Publisher:
University of Colorado Denver
Publication Date:
Language:
English

Thesis/Dissertation Information

Degree:
Master's ( Master of science)
Degree Grantor:
University of Colorado Denver
Degree Divisions:
Department of Civil Engineering, CU Denver
Degree Disciplines:
Civil engineering
Committee Chair:
Rutz, Frederick
Committee Members:
Kim, Yail Jimmy
Li, Chengyu

Notes

Abstract:
The topic of this thesis is the behavior of internally-cured high-performance concrete reinforced with glass fiber-reinforced polymer (GFPR) bars. The two main tests conducted were on the behavior of internally-cured high-performance concrete reinforced with GFRP bars and the strength of splices of GFRP bars embedded in internally cured concrete. Test phase one results show that with an increase of SAP/cement weight, the concrete slabs’ strength decreased. Test phase two results show that when the GFRP bars have the same splice length, the slabs’ failure load decreases with an increase of SAP/cement weight. When the SAP dosage is same, the slabs’ failure load will increase with an increase splice length.

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University of Colorado Denver
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Auraria Library
Rights Management:
Copyright Junhao Gao. Permission granted to University of Colorado Denver to digitize and display this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.

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BEHAVIOR OF INTERNALLY-CURED HIGH-PERFORMANCE CONCRETE REINFORCED WITH GLASS FIBER REINFORCED POLYMER BARS by J UNHAO GAO B .S., Northeast Forestry University,2014 A thesis submitted to the Faculty of the Graduation School of the University of Colorado in partial fulfillment of the requirements for the degree of Master of Science Civil Engineering Program 2017

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This thesis for the Master of Science degree by Junhao Gao has been approved for the Civil Engineering Program by Frederick Rutz , Chair Yail Jimmy Kim Chengyu Li Date: December 16,2017 ii

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Junhao Gao (M.S., Civil Engineering Program ) Behavior of Internally cured High performance Concrete Reinforced with Glass Fiber Reinforced Polymer Bars Thesis directed by Professor Yail Jimmy Kim. ABSTRACT The topic of this thesis is the behavior of internally cured high performance concret e reinforced with glass fiber reinforced polymer (GFPR) bars. T he two main tests conducted were on the behavior of internally cured highperformance concrete reinforced with GFRP bars and the strength of splice s of GFRP bars embedded in internally cured concrete. Test phas e one results show that with an increase of SAP/cement weight, the concrete slabs ’ strength decreas ed. Test phase two results show that when the GFRP bars have the same splice length, the slabs’ failure load decreases with an increase of SAP/cement weight. When the SAP dosage is same, the slabs’ failure load will increase with an increase splice length. The form and content of this abstr act are approved. I recommend its publication. Approved: Yail Jimmy Kim iii

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ACKNOWLEDGMENTS I would gratefully acknowledge financial support from the University of Colorado Denver (UCD) I would like to say thankyou to my advisor Dr. Kim, who gave me a lot of technical support for my research, and also helped me improve my English writing skills. I also want to thank Dr.Frederick Rutz and Dr.Chengyu Li, not only for being part of my graduate committee but also for teaching courses that I have taken. Dr.Chan g also helped me a lot. I want to thank Ibrahim Bumadian, Yongcheng Ji, Jungang Liu, Jun Wang, Lisa Wang,Changqi Shang, Yufei Chai, Shile Dong. Finally, I'd like to express my thanks to my family. They are standing behind me and supporting me silently. iv

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TABLE OF CONTENTS C ONTENTS CHAPTER I .............................................................................................................................. 1 INTRODUCTION .................................................................................................................... 1 1.1 Introduction ..................................................................................................................... 1 1.2 Research Significance ................................................................................................... 2 1.3 Objectives ..................................................................................................................... 2 1.4 Scope ............................................................................................................................. 3 1.5 Outline ........................................................................................................................... 4 CHAPTER II ............................................................................................................................. 5 LITERATURE REVIEW ......................................................................................................... 5 2.1 Introduction ................................................................................................................... 5 2.2 Fiber Reinforced Polymer (FRP) .................................................................................. 5 2.3 Glass Fiber Reinforced Polymer (GFRP) ...................................................................... 6 2.4 Super Absorbent Polymer (SAP) ................................................................................... 7 2.5 Internal Curing of Concrete .......................................................................................... 8 2.6 Splice Length ................................................................................................................ 9 2.7 DIC (Digital Image Correlation) ................................................................................... 9 CHAPTER III ......................................................................................................................... 20 STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS ....... 20 v

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3.1 Introduction ................................................................................................................... 20 3.2 Material for Test Specimens ....................................................................................... 20 3.2.1 Glass Fiber Reinforced Polymer (GFRP) bars ....................................................... 20 3.2.2 Concrete ................................................................................................................. 21 3.2.3 Super Absorbent Polymer (SAP) ........................................................................... 22 3.2.4 Strain Gauge ........................................................................................................... 23 3.2.5 Testing Tools ......................................................................................................... 23 3.3 Experimental Setup and Loading .................................................................................. 24 3.3.1 Setup ...................................................................................................................... 24 3.3.2 LoadDispl acement Behavior and Failure Modes ................................................. 24 3.3.3 LoadStrain Behavior ............................................................................................. 25 3.3.4 LoadGFRP Bars Strain Behavior ......................................................................... 25 3.4 Ancillary Test ................................................................................................................ 26 3.4.1 Cylinders Compressive Test .................................................................................. 26 3.4.2 SAP Water Absorbing Capacity Test .................................................................... 26 3.4.3 SAP Release Water Test ........................................................................................ 27 CHAPTER IV ......................................................................................................................... 60 SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE ........... 60 4.1 Introduction ................................................................................................................... 60 4.2 Material for Test Specimens ......................................................................................... 60 vi

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4.2.1 Glass Fiber Reinforced Polymer (GFRP) bars ....................................................... 60 4.2.2 Concrete ................................................................................................................. 63 4.2.3 Super Absorbent Polymer (SAP) ........................................................................... 64 4.2.4 Testing Tools ......................................................................................................... 65 4.3 Experimental Setup and Loading .................................................................................. 65 4.3.1. Setup ..................................................................................................................... 66 4.3.2 LoadDisplacement Behavior and Failure Modes ................................................. 66 4.3.3 LoadStrain Behavior ............................................................................................. 67 CHAPTER V ........................................................................................................................ 121 5.1 Summary and Conclusions ....................................................................................... 121 5.2 Recommendations for design .................................................................................... 122 5.3 Recommendations for Future Research ................................................................... 122 APPENDIX ........................................................................................................................... 124 RENFERENCES ................................................................................................................... 127 vii

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LIST OF TABLES Table. 3.1 Concrete mix design... 28 Table. 3.2 SAP amount .... 28 Table. 3.3 Properties of strain gauge ....... 29 Table. 3.4 Mechanical propert ies of #6 GFRP bar ...... 29 Table. 3.5 Summary of cylinder test ........ 30 Table. 3.6 Summary of slab tests ......... 30 Table. 4.1 Concrete m ix p roportions ....... 68 Table. 4.2 Mechanical properties of #3 GFRP bar ...... 68 Table. 4.3 Different category s labs for test t wo .................. 69 Table. 4.4 Splice l ength of GFRP bars ........ 70 Table. 4.5 Loadcarrying capacity of test specimens ....... 70 viii

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LIST OF FIGURES Fig.2.1 Acrylic acid chemical formula ....11 Fig.2.2 Sodium hydroxide chemical formula ..........11 Fig.2.3 Sodium polyacrylate chemical formula ...11 Fig.2.4 AFRP Bars ...........12 Fig.2.5 CFRP Tubs ..........12 Fig.2.6 CFRP Sheets ............12 Fig.2.7 BFRP Bars .......... 13 Fig. 2.8 Properties of Steel Bars .......... 13 Fig. 2.9 Properties of GFRP Bars .... 14 Fig. 2.10 Use CFRP sheets repair the bridge under deck spans at I 25 over Sheridan ..15 Fig.2.11 Corrosion steel bars in bridge deck spans at I 635 over State Ave ..................16 Fig.2.12. Install GFRP bars on bridge deck spans at I 635 over State Ave ...17 Fig.2.13 Connection of GFRP bars on bridge deck spans at I 635 over State Ave ...17 Fig. 2.14 Different outer surfaces of GRFP bars .....18 Fig. 2.15 Different ways to connect bars (Concrete Reinforcing Steel Institute) ......19 Fig.3.1 Specimen details (a) cross section;(b) reinforcing scheme ix

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Fig.3.2 Test set up (a) dimensions;(b) picture .................................................................32 Fig.3.3 Instrumentation: (a)Strain gauge;(b) Load Cell;(c) Liner potentiometer;(d) PI gauge .........................................................................................................................................34 Fig. 3.4 Cylinder tests pictures .........................................................................................35 Fig.3.5 Cylinder test ........................................................................................................36 Fig.3.6 Loadcarrying capacity of slabs ..........................................................................36 Fig.3.7 Summary of load displacement behavior ............................................................37 Fig.3.8 Summary of load strain response of slabs with different SAP dosage ratio.....37 Fig.3.9 Load displacement behavior: (a) 0% SAP Slab;(b) 0.1% SAP Slab;(c) 0.2% SAP Slab; (d) 0.3% SAP Slab;(e) 0.4% SAP Slab.....40 Fig.3.10 Load strain response of slabs with 0% SAP: (a) specimen1;(b) specimen2; (c) specimen3 . ... 42 Fig.3 .11 Load strain response of slabs with 0.1% SAP: (a) specimen1;(b) specimen2; (c) specimen3 . ... 43 Fig.3.12 Load strain response of slabs with 0.2% SAP: (a) specimen1;(b) specimen2;(c) specimen3 . ... 45 Fig.3.13 Load strain response of slabs with 0.3% SAP: (a) specimen1;(b) specimen2;(c) specimen3 . ... 46 Fig.3.14 Load strain response of slabs with 0.4% SAP: (a) specimen1;(b) specimen2; (c) specimen3 . ... 48 x

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Fig.3.15 Load GFRP bar strain( a)0%SAP;(b)0.1%SAP;(c)0.2%SAP; (d)0.3%SAP; (e)0.4%SAP .. ... 51 Fig.3.16 SAP absorbing capacity (volume time) ..51 Fig.3.17 SAP release water test(weight time) ...52 Fig.3.18 Summary for SAP water release ...52 Fig.3.19 Failure mode of slabs with 0% SAP .53 Fig.3.20 Failure mode of slabs with 0.1% SAP .54 Fig.3.21 Failure mode of slabs with 0.2% SAP .55 Fig.3.22 Failure mode of slabs with 0.3% SAP .56 Fig.3.23 Failure mode of slabs with 0.4% SAP .57 Fig.3.24 SAP Water Absorbing Capacity Test ..58 Fig. 3.25 SAP Release Water Test ..59 Fig.4.1 Specimen details: (a) reinforcing scheme; (b) cross section; (c)test setup; (d)picture . 73 Fig.4.2 Splice details: (a) variable splice length;(b) spacers;(c) placed bars(0.6ld) ....74 Fig.4.3 Instrumentation: (a) Load Cell;(b) Liner potentiometer;(c) PI gauge;(d) DIC ...76 Fig. 4.4 Ultimate load of speci mens (a) effect of splice length;(b) comparison ......77 Fig. 4.5 Ultimate load of specimens (a) effect of splice SAP;(b) comparison .....78 xi

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Fig.4.6 Load displacement of specimens with 0% SAP (a) 0.2ld; (b) 0.4ld; (c) 0.6ld; (d) 0.8ld; (e) 1.0ld .. .. ..79 Fig.4.7 Loaddisplacement of specimens with 0.2% SAP (a) 0.2ld; (b) 0.4ld; (c) 0.6ld ;(d) 0.8ld; (e) 1.0ld..........80 Fig.4.8 Loaddisplacement of specimens with 0.4% SAP (a) 0.2ld; (b) 0.4ld; (c) 0.6ld; (d) 0.8ld; (e) 1.0ld......81 Fig.4.9 Load strain response of slabs with 0% SAP (a) 0.2ld; (b) 0.4ld; (c) 0.6ld; (d) 0.8ld; (e) 1.0ld . .. ...84 Fig.4.10 Loadstrain response of slabs with 0.2% SAP(a) 0.2ld; (b) 0.4ld; (c) 0.6ld; (d) 0.8ld; (e) 1.0ld........87 Fig.4.11 Loadstrain response of slabs with 0.4% SAP(a) 0.2ld; (b) 0.4ld; (c) 0.6ld; (d) 0.8ld; (e) 1.0ld........90 Fig .4.12 Failure mode of slab with 0%SAP,0.2ld...91 Fig .4.13 Failure mode of slab with 0%SAP,0.4ld...92 Fig .4.14 Failure mode of slab with 0%SAP,0.6ld...93 Fig .4.15 Failure mode of slab with 0%SAP,0.8ld...94 Fig .4.16 Failure mode of slab with 0%SAP,1.0ld...95 Fig .4.17 Failure mode of slab with 0.2%SAP,0.2ld96 Fig .4.18 Failure mode of slab with 0.2%SAP,0.4ld97 Fig .4.19 Failure mode of slab wi th 0.2%SAP,0.6ld98 xii

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Fig .4.20 Failure mode of slab with 0.2%SAP,0.8ld99 Fig .4.21 Failure mode of slab with 0.2%SAP,1.0ld 100 Fig .4.22 Failure mode of slab with 0.4%SAP,0.2ld 101 Fig .4.23Failure mode of slab with 0.4%SAP,0.4ld .102 Fig .4.24 Failure mode of slab with 0.4%SAP,0.6ld 103 Fig .4.25 Failure mode of slab with 0.4%SAP,0.8ld 104 Fig .4.26 Failure mode of slab with 0.4%SAP,1.0ld 105 Fi g .4.27 DIC images for slab with 0%SAP at 0.2ld 106 Fig .4.28 DIC images for slab with 0%SAP at 0.4ld 107 Fig .4.29 DIC images for slab with 0%SAP at 0.6ld 108 Fig .4.30 DIC images for slab with 0%SAP at 0.8ld 109 Fig .4.31 DIC images for slab with 0%SAP at 1.0ld 110 Fig .4.32 DIC images for slab with 0.2%SAP at 0.2ld.111 Fig .4.33 DIC images for slab with 0.2%SAP at 0.4ld.....112 Fig .4.34 DIC images for s lab with 0.2%SAP at 0.6ld.113 Fig .4.35 DIC images for slab with 0.2%SAP at 0.8ld.114 Fig .4.36 DIC images for slab with 0.2%SAP at 1.0ld.115 Fig .4.37 DIC images for slab with 0.4%SAP at 0.2ld.116 xiii

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Fig .4.38 DIC images for slab with 0.4%SAP at 0.4ld.117 Fig .4.39 DIC images for slab with 0.4%SAP at 0.6ld.118 Fig .4.40 DIC images for slab with 0.4%SAP at 0.8ld.119 Fig .4.41 DIC images for slab with 0.4%SAP at 1.0ld.120 xiv

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NOTATION C = spacing or cover dimension, mm db = diameter of reinforcing bar, mm f’c = specified compressive strength of concrete, MPa f’fr = required bar stress, MPa ld = development length, mm H = idistance from the bottom of the bar to the bottom of the slab. = top bar modification fa ct o xv

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CHAPTER I INTRODUCTION CHAPTER I INTRODUCTION 1.1 Introduction High performance concrete (HPC) has become a newly developing word in the field of highway bridges. HPC is a type of high strength, durable , light weight construction member ( Aitcin,P.C . 2003).However HPC will have early age b ehavior. Autogenous shrinkage will happen in HPC, due to the self desiccation of concrete. One of the best way to solve this problem is internal curing, which is the use of an internal curing agent which can release water during the curing of the HPC and a ccelerate the hydration process of the concrete. Super absorbent polymer (SAP) is a type of internal curing agent. SAP can absorb 5000 times its own weight. SAP can release a lot of water during the curing time. This water will release during curing of the concrete and will resist autogenous shrinkage. SAP can help improve the internal curing but reduce the strength of concrete. Addin g SAP requires it to be combined with additional water. Fiber reinforced polymer (FRP) has a wide range of uses in different areas, especially in the field of construction. FRP bars can be a structural member in place of steel bars in concrete structure s ( ACI 440.1R 06). FRP increases the durability of the construction, because FRP can resist chemicals, moisture and insects. It s light weight is one of the most important mechanical proper ties of FRP. Glass f iber reinforced polymer (GFRP) is one of the FRP materials which is most commonly used in the field of construction. GFRP h as all the advantages of FRP . GFRP’ s 1

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tensile strength is two times greater than steel and there is no yield strain. GFRP bars have become one of the structural members for high performance concrete. 1.2 Research Significance The previous research focused on GFRP mechanical properties a nd behavior. Creaeye,B; Geirnaert,M; and De Schutter,G et al(2010) found the autogenous shrinkage for high performance concrete reduced with the addition of an amount of SAP to concrete. Cusson,D ;Lounis,Z;and Daigle,L (2010) found internal curing in high performance concrete can reduce lift cycle cost over normal curing . Kim. Y. J; Wang.J (2016) found the interfacial of stress of GFRP bar concrete decreased with increasing SAP addition ratio . This research combined GFRP, HPC slabs and SAP. The focus wa s on the behavior of GFRP bars embedded in internally cured concrete with various amounts of SAP and the various splice lengths of GFRP bars embedded in internally cured concrete . Recommendation on the structural design in construction field and future res earch were given. 1.3 Objectives This thesis studies the behavior of internally cured highperformance concrete reinforced with GFRP bars through two main tests. The first test examines the strength of internally cured high performance concrete reinforced with GFRP bars . A ncillary tests help analyze results from the main test. The objectives are: 1. Comparison of the loadcarrying capacity for GFRP bars embedded in concrete slabs with various SAP amounts (SAP/cement weight ratio: 0%, 0.1%, 0.2%, 0.3%, 0.4%). 2

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CHAPTER I INTRODUCTION 2. Analyze the failure mode of all the concrete slabs with various amount s of SAP ( SAP/cement weight ratio s: 0%, 0.1%, 0.2%, 0.3%, 0.4%) . 3. Evaluation of the load displacement behavior, loadstrain behavior and loadGFRP bars strain behavior The objectives for the second test (the splice lengths of GFRP bars embedded in internally cured concrete) are: 1. Comparison of the loadcarrying capacity for the same sp lice length GFRP bars embedded in concrete slabs with various amount of SAP (SAP/cement weight ratios: 0%, 0.2%, 0.4%). 2. Comparison of the loadcarrying capacity for various s plice length s of GFRP bars (0.2ld, 0.4ld, 0.6ld, 0.8ld, 1.0ld) embedded in concrete slabs with the same amount o f SAP . 3. Evaluation of the load displacement behavior and load s train behavior . 4. Analyze the failure mode of various s plice length s of GFRP bars (0.2ld, 0.4ld, 0.6ld, 0.8ld, 1.0ld) embedded in concrete slabs with various amount s of SAP (SAP/cement weight ratio 0%, 0.2%, 0.4%). 5. Use the result to give a recommendation on the structural design and future research. 1.4 Scope For the tests of GFRP bars embedded in concrete sla bs with various SAP amounts , fifteen concrete slabs need ed to be prepared. A four point test with actuator was used. The following data points were collected: load, middle span displacement, middle span strain and GFRP bars’ middle span strain. The data was collected with a load cell, a liner potentiometer, 3

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PI gauge s and strain gauges. PI gauges are displacement transducers. PI gauges used to record the middle span strain of the concrete slabs in horizontal direction during the tests. Fifteen cylinders with various SAP/cement weight ratio were prepared for concr ete strength test. To test the s plice of GFRP bars e mbedded in i nternally c ured c oncrete test , fifteen slabs also needed to be prepared. A four point test with actuator was used. The following data was collected load, middle span displacement, middle span strain a nd grain scale digital image correlation with load cell, liner potentiometer, PI gauges and digital image correlation ( DIC ) . 1.5 Outline This thesis has five chapters. Chapter 1 presents the outline of the tests and the research goal. Literatur e r eview is in chapter 2. Mainly it introduces the materials used in the tests. GFRP and SAP have become more and more popular in construction. Chapter 2 also introduces some projects using these materials. Chapter 3 focuses on the phase one test relating to the strength of internally cured HPC reinforced with GFRP bars. Also included is discussion of the ancillary tests of concrete cylinder strength at 28 days, SAP w ater absorbing capacity t est , SAP release water t est and three point prisms test. The materials and tools used in test are introduced with pictures. The s plice of GFRP bars e mbedded in internally cured c oncrete will be discussed in chapter 4. Design recommendations also will be introduced in chapter 4. Chapter 5 co ntains the summary an d c onclusions . Recommendations for future research are also provided. 4

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CHAPTER II LITERATURE REVIEW CHAPTER II LITERATURE REVIEW 2.1 Introduction This chapter introduces the background of materials used in tests. The application and history of FRP are presented. The advantage of GFRP bars is also mentioned in this chapter. The past investigations of SAP focus ed on its influence on concrete strength. If some amount of SAP is added to concrete, its strength will improve, du e to the increased curing time. The more SAP added into concrete decreases the concrete ’s strength (Shan, J.H and Guo, S.W 2015). 2.2 Fiber Reinforced Polymer (FRP) FRP is Fiber Reinforced Polymer and is also called Fiber Reinforced Pl astic. FRP has a lot of categories , e.g. Aramid Fiber Reinforced Polymer (AFRP) [Fig.2.4] , Fiber Reinforced Polymer (BFRP) [Fig.2.7] , Carbon Fiber Reinforced Polymer (CFRP) [Fig.2.5] [Fig.2.6] , and Glass Fiber Reinforced Polymer (GFRP). Bak elite was the first type of fiber reinforced plastic, prod uced by Leo Baekeland in 1905. In the1930s, fiber reinforced plastic was deeply researched. FRP has very wide application and has even been used to build a plane, the Fairchild F 46. C arbon fiber and aramid fiber productions were both first made in the 1950s. Aramid, carbon and glass fibers were used widely in middle 20th century . In the later 1970s, people began to use FRP reinforcing bars as viable solution to replace the steel reinfo rcing bars used in construction. 5

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CHAPTER II LITERATURE REVIEW FRP bars wh en compared with steel bars, have man y advantages. An FRP bars density is 1/6 to1/4 that of steel. The lower weight advantage will be introduce d in Section 2.3. FRP has a wide range of use in construction. It is the most common material used to increase construction durability. FRP can increase the strength of structural members. I t also can repair damaged construction members. CFRP sheets can repair cracking bridge columns and defend against corrosion by acid rain. Colorado Department of Transportation (CDOT ) project C20781 used CFRP sheets to repair the bridge underdeck spanning I 25 at Sherida n in Denver, Colorado [Fig.2.10] . 2.3 Glass Fiber Reinforced Polymer (GFRP) GFRP has a very high strength to weight ratio. GFRP’s weight is lower than steel for bar s with the same cross section. A #3 GFRP bar is 0.107 l b/ft while a #3 s teel bar i s 0.378 lb/ft. A s teel bar ’s weight is nearly 4 times that of a same size GFRP bar. The tensile strength of GFRP is from 483MPa to 1600MPa, while steel is from 483MPa to 690 MPa. GFRP does not have yield strain, but steel has a yield strain from 0.14% to 0.25%. Therefore , GFRP has a lot of advantages in construction to include: faster installation, lower shipping cost, and less structural framing. In a chemical rich and moisture laden environment, steel may corrode and wood may decay . Compared with traditional construction materials, steel and wood , GFRP performs much better. It can resist chemicals, moisture and insects. A house built with timber may warp, rot and decay due to flooding and acid rain. Something built with steel, if exp osed to acid rain, may corrode. KDOT (Kansas Department of Transportation) used GFRP bars to 6

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CHAPTER II LITERATURE REVIEW replace corroded steels bar in the concrete bridge deck spanning I 635 over State Ave in Kansas City [Fig.2.13] . GFRP has different outer surfaces [Fig.2.14] . The main three categories are sand/fabric coated, sand coated deformed and helical wrapped/ribbed. Sand/fabric coated GFRP can help increase by 40% the bond behavior between GFRP bars and concrete. Sand/fabric coated GFRP also can enhance the ability of resis t ing corrosion, acid and alkali during construction (Xue, W.C and Tan, Y 2012). Helical wrapped/ribbed GFRP bar s have an even higher bond behavior than the sand/fabriccoated surface, but the diameter of the aggregate is a restriction. If the aggregate’s d iameter is larger than the helical angle, the void’s volume will decrease the bond behavior. 2.4 Super Absorbent Polymer (SAP) SAP can absorb large amounts of liquid beyond its own mass and volume. SAP also can reserve liquid for a long time. Polymerization of acrylic acid blended with sodium hydroxide can form sodium polyacrylate [Fig.2.2] [Fig.2.3] . Sodium polyacrylate is the most common type of SAP used in the world. Before the 1920s, water absorbin g materials could only absorb 11 times their mass of water and most of that water will be lost due to pressure. Those materials are cotton, tissue paper and so on. A round the 1960s, the United S tates Department of Agriculture (USDA) discovered a polymer called “Super Slurper” , which can absorb 400 times its w eight of water. SAP’s first wide range use was as feminine napkins in Japan in 1978. SAP ha s always been used in disposable hygiene products, e.g. baby diapers. They can also be used to prevent water 7

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CHAPTER II LITERATURE REVIEW pe rmeating something , such as an underground power line. SAP can absorb up to 5000 times its own weight . In 1997, O.Mejlhede Jensen and Per Freiesleben Hansen began to initiate a series of tests of a new curing technique. This is the first time SAP was used with concrete. They found SAP can increase the efficiency of internal water curing. SAP will reduce the strength of the concrete slightly , but SAP can increase the concrete’s durab ility. In construction, SAP can also be used as an alternative air entrainment agent to defend against frost. Although the concrete strength will reduce initially when SAP is added, after 28 days the concrete’s strength will increase due to the water release from SAP which improve s the hydration reaction of cement . However, when the increas ing the amount of additional water for SAP, reduces the concrete’s strength. The reason for the concrete strength decrease is that the SAP may leave lots of holes behind when the water is released (Shan, J.H and Guo, S.W 2015) . 2.5 Internal Curing of Concrete Internal curing is a way to provide extra water during the concrete curing period. The extra water comes from the internal curing agent , which is a type of material that can absorb a lot of water and then release that water du ring curing. The most common internal curing agents are light weight aggregate (LWA), crushed returned concrete aggregate(CCA) and SAP. LWA and CCA replace the aggregate in the conventional concrete mix design. LWA and CCA can only absorb an amount of wate r less than their mass (Kim, Y.J and Wang, J et al 2016). SAP can absorb water 5000 times its mass and does not replace the aggregate. Internal curing not only reduces highperformance concrete’s autogenous shrinkage, it can also reduce curing work during the construction process, because internal curing agents can release water during the concrete’s curing period. In the mid1950s, Paul Klieger was the first person to find the 8

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CHAPTER II LITERATURE REVIEW internal curing. In the 1990s, people began to use internal curing in the field of construction and now more research is being conducted into about internal curing and internal curing agents. 2.6 Splice Length R ebar’s length is usually 60 ft or less but for some huge projects, e.g. long span bridges , it might be longer. During construction, long bars are needed to put in the concrete, but the bars also need to be easy to ship. The l ap splice became the best way to solve this problem. A lap splice of two bars is overlapping of those two same length bars to some degree and wiring them together. The test of the splice of GFRP bars embedded in internal cured concrete is to figure out how long an overlap length is best for used in construction. The best being the most economical, with enough strength and eas y to ship. The length of a lap splice varies with many conditions such as concrete strength, type of concrete, the yield strength of the reinforcing bars, bar size, bar spacing, concrete cover, and the numb ers of ties or stirrups required (ACI 440.1R 06).The simple lap splice, welded lap splice and coupler are the most common methods used in construction to connect the splice d bars. A simple lap splice is easy and quick to install and is economical, but it has less strength than the welded lap splice or co upler. The welded lap is more economical than the coupler [Fig .2.15] . 2.7 DIC (Digital Image Correlation) DIC is a new technique to measure displacement and strains. In recent years, DIC has been widely us ed in the areas of applied science and civil engineering. The first time cross correlation was applied to digital images was in the early 1970s (Keating, T.J.; Wolf, P.R and 9

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CHAPTER II LITERATURE REVIEW Scarpace, F.L 1975) (Anuta, P.E 1970). DIC can track several points on the image, and use the movement of those points to analy ze strain and displacement. DIC is used in phase two, the s plice of GFRP bars e mbedded in i nternally c ured concrete. To use DIC, a white background was painted on the side of the slab without PI gauges and at the middle span. The paint ed area is 400mm by 127 mm wide. After the white background dried, some dark color points were added which are easy for DIC to track. 10

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CHAPTER II LITERATURE REVIEW Figure .2.1 Acrylic acid chemical formula Figure. 2.2 Sodium hydroxide chemical formula Fig.2.3 Sodium polyacrylate chemical formula 11

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CHAPTER II LITERATURE REVIEW Fig.2.4 AFRP Bars Fig.2.5 CFRP Tub s Fig.2.6 C FRP Sheets 12

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CHAPTER II LITERATURE REVIEW Fig.2.7 B FRP Bars Fig. 2.8 P roperties of Steel Bar s 13

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CHAPTER II LITERATURE REVIEW Fig. 2.9 P roperties of GFRP Bar s [ http://www.aslanfrp.com/Media/Aslan100.pdf ] 14

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CHAPTER II LITERATURE REVIEW Fig. 2.10 Use CFRP sheets repair the bridge under deck spans at I 25 over Sheridan 15

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CHAPTER II LITERATURE REVIEW Fig.2.11 Corrosion steel bars in bridge deck spans at I 635 over State Ave [ http://www.aslanfrp.com ] 16

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CHAPTER II LITERATURE REVIEW Fig.2.12. Install GFRP bars on bridge deck spans at I 635 over State A ve [ http://www .aslanfrp.com] Fig .2.13 Connection of GFRP bars on bridge deck spans at I 635 over State Ave [ http://www .aslanfrp.com] 17

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CHAPTER II LITERATURE REVIEW Fig. 2.14 D ifferent outer surfaces of GRFP bars 18

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CHAPTER II LITERATURE REVIEW (a) Simple Lap Splice (b) Welded Lap Splice (c) Coupler (Divide into a lot of different methods) Fig 2.15 Different ways to connect bars [ http://www.crsi.org/index.cfm/steel/splices ] 19

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS CHAPTER III STRENGTH OF INTERNALLYCURED HPC REINFORCED WITH GFRP BARS 3.1 Introduc tion The first phase test is the strengt h of internally cured HPC (High Performance Concrete) reinforced with GFRP bars and SAP addition ratios of 0%, 0.1% 0.2%, 0.3% and 0.4%. There were three slabs per category and five categories for fifteen slabs total. For the concrete details see S ection 3.2.2. The slabs cured at room temperature for 28 days. All the slabs used a four point flexural test with actuator [Fig .3.2] . Load and displacement were recorded by an additional load cell and a liner potentiometer. PI gauges recorded tension strain and pressure strain. Each category only has one slab with an installed strain gauge , which was located at the middle of the bars to record the strain. This chapter also introduces two different ancillary test s : the cylinder compress ion test and the SAP water absorbing capacity test . 3.2 Material for Test Specimens 3.2.1 Glass Fiber Reinforced Polymer ( GFRP ) bars This test used No.6 GFRP bars with a 19mm diameter and a length of 1524 mm. A No.6 GFRP bar’s cross section is 285mm2 and it has an ultimate tensile strength of 690 MPa with a tensile modulus of elasticity of 46GPa. All the mechanical properties of a No.6 GFRP bar are shown in Ta ble 3.4. The bars ’ surfaces are all s and/fabric coated , which can increase the bond behavior between GFRP bars and concrete by up to 40% . The wood mold’s 20

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS dimensions are 1625.6 mm length by 304.8 mm width and 127 mm deep. Each slab has two GFRP bars inside. Each bar has a 50.8mm covering layer on each side. The bars are 25.4 mm from the end of the beam to end of the bar [Fig.3.1] . Plastic spacers were used to make sure the GFRP bars were 25.4 mm above the bottom of the slabs. Steel wire was used to fix the bars ’ position in the mold. 3.2.2 Concrete The 15 slabs were cast using 5 different concrete mix es . Each category h as 3 specimens [ Table. 3.1] . The only difference is the SAP dosage [ Table 3.2] . Each slab need ed 13.52 kg water, 28.1 kg cement, 37.74 k g sand, 68.88 kg aggregate and vari ous amount s of SAP [ Table. 3.2] . All the materials need ed to be mixed in the correct order during the mixing of the concrete. The aggregate, sand , and cement are added first, and then mixed well before adding water and mixing well again. The last step was to add saturated SAP into the mixer and combi ni ng well again. This test used Portland Type 3 cement cured for 28 days at room temperature. Portland Type 3 cement will let the concrete’s strength increase in the first 7 days and the concrete ’s strength will increase a little bit during the 28 day s cure. After 28 days, concrete’s strength will remain stable. The concrete slabs were tested after 28 days to make sure the concrete strength was not influenced by the time it w as allowed to cure. The concrete was cast in a kiln dried cedar mold. Cedar is lightweight allowing the mold to be easily moved. Cedar’s most important characteristics are its strength and resistance to decay. These two features can increase mold durabi lity. Three types of Simpson Strong Tie s were used to connect the cedar: 113/16 in. x 5 in. tie plate, Z MAX 2 in. x 4 in. 12gauge 21

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS galvanized medium L angle , and ZMAX 18 gauge galvanized steel angle . Three “U” shape steel hooks were placed in each beam. 24 hours after the concrete was cast, iron chain was placed into the three steel hooks. An overhead crane was used to lift the slabs out of the mold. After the mold was removed, plastic wrap was used to wrap the whole slab to resist the effect s of external water, letting the SAP inside the concrete absorb the internal water only. The concrete slab size is 1625. 6mm long, 304.8 mm wide and 127 mm deep. Its total weight is 147.5634kg. 3.2.3 Super Absorbent Polymer (SAP) The SAP dosage ratio was based on the cement’s weight. This test has 5 different SAP dosage ratios, 0%, 0.1%, 0.2%, 0.3% and 0.4% SAP/cement weight . With the increased dosage of SAP, the amount of water for SAP also increased [Table. 3.2]. The water added for SAP is different from the water used the concrete mix. The wate r for the normal concrete mix helps the aggregate, sand and cement mix well. The water for the SAP is saturate s the SAP prior to its being added to the concrete mixer. The following steps need to be followed when adding SAP to the concrete mix. First, weigh the SAP and then put SAP into a bucket . Second, weigh the amount of water for SAP. SAP absorbs all the water and is saturated in 7 minutes . Finally, add the saturated SAP to the mixer and combi ne well again. The water absorbed by the SAP releases during the curing and helped the concrete’s internal curing. 22

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS 3.2.4 Strain Gauge The strain gage used in this test is from KYOWA [Table. 3.3] . This test has 15 slabs, 5 categories, and each category has 3 specimens, only one slab has strain gauges. Each of these slab s has two GFRP bars, each bar with one stain gauge on the midspan. [Fig. 3.1] . Each strain gauge was wired into place. Ten strain gauges were needed for this test, each protected by silica gel [Fig .3.3(a) ]. 3.2.5 Testing Tools An additional load cell was used to record the load and was located in the middle of the steel frame and actuator [Fig .3.3(b)]. PI gauges were located in th e middle of the slab’s side. Before installing the PI gauges, glue was used to affix 4 nails to the side of the slab in the middle of the slab. The upper two nails were 25.4 mm from the top of the slab. The lower two nails were 25.4 mm from the bottom of t he slab. Both sets of nails have a horizontal distance of 101.6 mm. Before testing, all the nails needed to cure for 24 hours to make sure the nails w ould not detach during the test. The linear potentiometer needed to be placed vertical to the bottom of slab. It was fixed under the middle span of the slabs [Fig .3.3(c) ]. Strain gauges were glued by epoxy to the middle span of the GFRP bars. Silica gel was used to protect the strain gauge and the connection between strain gauge and output wire. Before casting the concrete, the silica was allowed to dry totally. The output wire needed to connect with DATAQ. The wire length needed was at least 800 mm, longer th en the half of slab length. All the data from load cell, PI gauges, linear potentiometer and strain gauges was collected by DATAQ. 23

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS 3.3 Experimental Setup and Loading The followin g sections detail the test preparation , setup and method of loading for the e xperimental program. The way to apply the load and support details are also discussed. The data collection method is introduced in this section. The l oad displacement behavior, loads train behavior , load GFRP bars strain behavior and failure are also inclu ded in this chapter. 3.3.1 Setup This test is a four point flexure test. It has two supports, and two loading points. Two steel strips were put on the loading points. A “U” shape steel frame was placed above the two loading points. The distance between the two loading points is 432 mm. The load cell was put on the steel frame. A flat steel plate was placed between the actuator and the load cell to ensure application of a stable force. The distance from each support to the end of the beam is 203.3 mm. Slabs will be loaded at a rate of 10 mm/min until failure [Fig.3.2] . 3.3.2 Load Displacement Behavior and Failure Modes Fig.3.8 shows the loadcarrying capacity of slabs decreases with increased the SAP ratio (SAP/cement weight). All the failure load for slabs display on the Table 3.6. The failure mode of the slabs is shown in Fig .3.19 to Fig .3.2 3. The five categories concrete slabs’ failure mode is shown with global and local pictures. Based on the failure mode pictures, the failure crack happened between the loading point and the support point. The failure crack shows the failure type is shear compression failure , which means the concrete failed ear l ier than the 24

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS GFRP bars yield. In the middle of the slabs , there was also had flexural crack ing but it did not cause the concrete failure. Fig .3.9 (a) shows that slabs without the addition of SAP have consistent behavior. All the curves very close. 3.3.3 Load Strain Behavior Concrete s lab t ension was recorded by the down PI gauge and pressure was recorded by the up PI gauge. Fig . 3.10 to 3.14 show the loadstrain response of slabs with 0%, 0.1%, 0.2%, 0.3% and 0.4%SAP. The up PI gauge was set up 25.4mm below the top of the slab on side of the middle span. The down PI gauge was set up 25.4mm below the bottom of the slab on side of the middle span. During the test, some PI gauges were dropped on the ground, see F ig .3.11 (a). The up PI gauge dropped when the load was applied. 3.3.4 Load GFRP Bars Strain Behavior The l oad GFRP bars’ strain is shown in Fig .3.15. E ach category has one slab with two strain gauges on the middle span of the GFRP bars. Fig . 3.15(d) only display one line in the figure, because the one of the strain gauges was unusable. The other figures show maximum strain data in same range. The data fo r the strain gauges from the same slab has a similar curve. 25

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS 3.4 Ancillary Test 3.4.1 Cylinders Compressive Test The cylinders are 101.6 mm diameter and 203.2 mm height. There 15 cylinders with an SAP replacement: 0%, 0.1%, 0.2%, 0.3% and 0.4% (3 cylinders per category). The concrete mix used was the same as th at used for the concrete slabs. After the plastic mold was removed plastic wrap was used to wrap the whole cylinder. All the specimens were tested after curing at room temperature for 28 days. The compression test was done with a 90kN (20kips) universal testing machine, as shown in Fig .3.4. Specimens were loaded at a rate of 0. 3mm/min until concrete failure. Table. 3.5 indicates that cylinder strength will decrease with an increase of the SAP/cement ratio. 3.4.2 SAP Water Absorbing Capacity Test A beaker was used as a container. 7.7g SAP was weighed and 350ml water was added . SAP has a density of 659kg/m3. The i nitial SAP volume was 0.000011684m3 (11.68ml) . Every 15 seconds a picture was taken. The SAP absorbed the water very quickly in first 3 minutes and then the absorption rate decreased. After 7 minutes, SAP reached t he final water saturation ratio. The final volume of SAP is 450ml [ Fi g .3. 24] . SAP ’s volume enlarged 38.5 time after abso rbed all the water in beaker. 26

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS 3.4.3 SAP Release Water Test The SAP initially weighed 8.8g and 396 ml water was added. The SAP was weighed every day. After 3 days the SAP released 2.3 g of water, Fig .3.24. After tw o weeks, the SAP released 9.1 g of water. For a slab with 0.1% SAP/cement weight added , 28.1g SAP was needed. This amount of SAP can release 33.1ml of water for internal curing . For a slab add 0.2% SAP/cement weight, 56.2g of SAP was needed , and it can release 66.2ml of water for internal curing . For a slab with 0.3% SAP/cement weight added , 84.3g of SAP was needed , and it can release 99.3ml water for internal curing . For a slab with 0.4% SAP/cement weight added , 112.4g of SAP was needed and it release 132.4ml water for internal curing. 27

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS Table. 3.1 Concrete m ix p roportions Material Dosage Weight (Slab Volume=64in*5in*12in=3840in=0.0629m) Water 2 15 kg/ m 2 1 5 kg/ m x 0.0629 m=13.52 kg [1] Cement 446 kg/ m 446 kg m x 0.0629 m= 28.1kg Sand 600 kg/ m 600 kg/ m x 0.0629 m=37.74 kg Aggregate 1095 kg/ m 1095 kg/ m x 0.0629 m=68.8 8kg SAP [2] Varies [ 3 ] Varies [1 ] Type III Portland cement (High early strength , curing 28days ) [2] Varibale amount of SAP [3 ] Table 3.2 Table. 3.2 SAP amount SAP Water for SAP SAP/Cement = 0.1% = 28.1kg*0.1% = 0.0281kg 1280 ml SAP/Cement = 0.2% = 28.1kg*0.2% = 0.0562kg 2560.4 ml SAP/Cement = 0.3% = 28.1kg*0.3% = 0.0843kg 3840.6 ml SAP/Cement = 0.4% = 28.1kg*0.4% = 0.1124kg 5128.8 ml 28

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS Table. 3.3 Properties of s train ga u ge Materials r esistive element CuNi alloy foil Materials b ase Polyimide Operating temperature ranges in combination with major adhesives after curing (C) CC 33A: 196 to 120C Operating temperature ranges in combination with major leadwire cables (C) Polyester coated copper cable: 196 to 150C Selftemperature compensation range (C) 10 to 100C Applicable linear expansion coefficient (0 6 /

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS Table.3.5 Summary of cylinder test Specimen Compressive strength (MPa) 1 2 3 AVG SAP 0% 27 .68 20.5 0 26. 62 24.9 SAP 0.1% 18.78 16. 34 15.61 16.9 SAP 0.2% 12.23 12.43 13.99 12.88 SAP 0.3% 11.53 11.45 11.7 3 11.57 SAP 0.4% 8.45 10.42 10.46 9.78 Table.3.6 Summary of slab tests Specimen Ultimate load (kN) 1 2 3 AVG SAP 0% 56.93 52.24 53.58 54.25 SAP 0.1% 47.63 47.08 51.47 48.7 3 SAP 0.2% 44.45 43.9 0 50.89 4 6 . 41 SAP 0.3% 39. 89 40.41 42.74 4 1 . 01 SAP 0.4% 35.83 31.09 35.79 3 4 . 24 30

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS (a) (b) (c) Fig.3.1 Specimen details (a) cross section (b) reinforcing scheme (c)picture 127 m 50.8 m 9.525 m 25.4 m 304.6 mm 31

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS (a) (b) Fig.3.2 Test set up (a) picture ; (b) dimensions 32

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS (a) (b ) (c) 33

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS (d) Fig.3.3 Instrumentation: (a) Strain gauge (b) Load Cell (c) Liner potentiometer (d) PI gauge 34

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS Fig. 3.4 Cylinder tests pictures 35

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS 0 10 20 30Stress (Mpa)Different Ratio of SAP Fig.3.5 Cylinder test 1 2 3 AVG 0%SAP 0.1%SAP 0.2% SAP 0.3%SAP 0.4%SAP 0 10 20 30 40 50 60Load (kN)Different Ratio of SAP Slab Fig.3.6 Loadcarrying capacity of slabs 1 2 3 AVG0%SAP 0.1%SAP 0.2%SAP 0.3%SAP 0.4%SAP36

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS 0 10 20 30 40 50 60 0 5 10 15 20 25 30Load (kN)Displacement(mm) Fig.3.7 Summary of loaddisplacement behavior 0%SAP 0.1%SAP 0.2%SAP 0.3%SAP 0.4%SAP 0 10 20 30 40 50 60 0.000 0.002 0.004 0.006 0.008 0.010 0.012Load (kN)Strain Fig.3.8 Summary of loadstrain response of slabs with different SAP dosage ratio 0%SAP 0.1%SAP 0.2%SAP 0.3%SAP 0.4%SAP 37

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS 0 10 20 30 40 50 60 -2 3 8 13 18 23 28Load (kN)Displacement(mm) (a) Slab No.1 Slab No.2 Slab No.3 0 10 20 30 40 50 60 -2 3 8 13 18 23 28Load (kN)Displacement(mm) (b) Slab No.1 Slab No.2 Slab No.3 38

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS 0 10 20 30 40 50 60 -2 3 8 13 18 23 28Load (kN)Displacement(mm) (c) Slab No.1 Slab No.2 Slab No.3 0 10 20 30 40 50 60 -2 3 8 13 18 23 28Load (kN)Displacement(mm) (d) Slab No.1 Slab No.2 Slab No.3 39

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS Fig.3.9 Load displacement behavior: (a) 0% SAP Slab (b) 0.1% SAP Slab (c) 0.2% SAP Slab (d) 0.3% SAP Slab (e ) 0.4% SAP Slab 0 10 20 30 40 50 60 -2 3 8 13 18 23 28Load (kN)Displacement(mm) (e) Slab No.1 Slab No.2 Slab No.3 40

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS 0 10 20 30 40 50 60 -0.002 0.000 0.002 0.004 0.006 0.008 0.010Load (kN)PI gauge (a) Up PI Down PI 0 10 20 30 40 50 60 -0.002 0.000 0.002 0.004 0.006 0.008 0.010Load (kN)PI gauge (b) Up PI Down PI 41

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS Fig.3.10 Load strain response of slabs with 0% SAP: (a) specimen1; (b) specimen2; (c) specimen3 0 10 20 30 40 50 60 -0.002 0.000 0.002 0.004 0.006 0.008 0.010Load (kN)PI gauge (c) Up PI Down PI 0 10 20 30 40 50 60 -0.002 0.000 0.002 0.004 0.006 0.008 0.010Load (kN)PI gauge (a) Up PI Down PI 42

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS Fig.3.11 Load strain response of slabs with 0.1% SAP: (a) specimen1; (b) specimen2;(c) specimen3 0 10 20 30 40 50 60 -0.002 0.000 0.002 0.004 0.006 0.008 0.010Load (kN)PI gauge (b) Up PI Down PI 0 10 20 30 40 50 60 -0.002 0.000 0.002 0.004 0.006 0.008 0.010Load (kN)PI gauge (c) Up PI Down PI 43

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS 0 10 20 30 40 50 60 -0.002 0.000 0.002 0.004 0.006 0.008 0.010Load (kN)PI gauge (a) Up PI Down PI 0 10 20 30 40 50 60 -0.002 0.000 0.002 0.004 0.006 0.008 0.010Load (kN)PI gauge (b) Up PI Down PI 44

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS Fig.3.12 Load strain response of slabs with 0.2% SAP: (a) specimen1; (b) specimen2; (c) specimen3 0 10 20 30 40 50 60 -0.002 0.000 0.002 0.004 0.006 0.008 0.010Load (kN)PI gauge (c) Up PI Down PI 0 10 20 30 40 50 60 -0.002 0.000 0.002 0.004 0.006 0.008 0.010Load (kN)PI gauge (a) Up PI Down PI 45

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS Fig.3.13 Load strain response of slabs with 0.3% SAP: (a) specimen1; (b) specimen2;(c) specimen3 0 10 20 30 40 50 60 -0.002 0.000 0.002 0.004 0.006 0.008 0.010Load (kN)PI gauge (b) Up PI Down PI 0 10 20 30 40 50 60 -0.002 0.000 0.002 0.004 0.006 0.008 0.010Load (kN)PI gauge (c) Up PI Down PI 46

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS 0 10 20 30 40 50 60 -0.002 0.000 0.002 0.004 0.006 0.008 0.010Load (kN)PI gauge (a) Up PI Down PI 0 10 20 30 40 50 60 -0.002 0.000 0.002 0.004 0.006 0.008 0.010Load (kN)PI gauge (b) Up PI Down PI 47

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS Fig.3.14 Load strain response of slabs with 0.4% SAP: (a) specimen1; (b) specimen2; (c) specimen3 0 10 20 30 40 50 60 -0.002 0.000 0.002 0.004 0.006 0.008 0.010Load (kN)PI gauge (c) Up PI Down PI 48

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS 0 10 20 30 40 50 60 -0.001 0.001 0.002 0.003 0.004 0.005 0.006Load (kN)Strain Gage No.1 and No.2 (%) (a) Strain gauge No.1 Strain gauge No.2 0 10 20 30 40 50 60 -0.001 0.001 0.002 0.003 0.004 0.005 0.006Load (kN)Strain Gage No.1 and No.2 (%) (b) Strain gauge No.1 Strain gauge No.249

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS 0 10 20 30 40 50 60 -0.001 0.001 0.002 0.003 0.004 0.005 0.006Load (kN)Strain Gage No.1 and No.2 (%) (c) Strain gauge No.1 Strain gauge No.2 0 10 20 30 40 50 60 -0.001 0.001 0.002 0.003 0.004 0.005 0.006Load (kN)Strain Gage No.1 and No.2 (%) (d) Strain gauge No.150

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS Fig.3.15 Load GFRP bar strain(a)0%SAP;(b)0.1%SAP; (c )0.2%SAP; (d)0.3%SAP;(e)0.4%SAP 0 10 20 30 40 50 60 -0.001 0.002 0.004 0.006Load (kN)Strain Gage No.1 and No.2 (%) (f) Strain gauge No.1 0 50 100 150 200 250 300 350 400 450 500 0 30 60 90 120 150 180 210 240 270 300 330 360 390Volume (ml)Time (s) Fig.3.16 SAP absorbing capacity (volume time) 51

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS 350 360 370 380 390 400 410 0 5 10 15 20 25 30Weight(g)Time (day) Fig.3.17 SAP release water test(weight time) 13510 13560 13610 13660 13710 13760 13810 13860 13910 13960 0 5 10 15 20 25 30Weight(g)Days Fig.3.18 Summary for SAP water release 0.1%SAP Water release 0.2%SAP Water release 0.3%SAP Water release 0.4%SAP Water release 52

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS Fig.3.19 Failure mode of slabs with 0% SAP 53

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS Fig.3.20 Failure mode of slabs with 0.1% SA P 54

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS Fig.3.21 Failure mode of slabs with 0.2% SAP 55

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS Fig.3.22 Failure mode of slabs with 0.3% SAP 56

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS Fig.3.23 Failure mode of slabs with 0.4% SAP 57

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS Fig.3.24 SAP Water Absorbing Capacity Test 58

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CHAPTER III STRENGTH OF INTERNALLY CURED HPC REINFORCED WITH GFRP BARS Fig 3. 25 SAP Release Water Test 59

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE CHAPTER IV S PLICE OF GFRP B ARS EMBEDDED IN INTERNALLY CURED CONCRETE 4.1 Introduction The second phase test is the splice of GFRP bars e mbedded in internally cured concrete One slab per category, fifteen categories, fifteen slabs total. Three vari ous amount s of SAP (0%, 0.2% , 0.4% SAP by cement weight) and five vari ous splice length s ( 0.2ld=192mm; 0.4ld=384mm; 0.6ld=577mm; 0.8ld=769mm; 1.0ld=962mm ) were used in this test. For the concrete’s details see Section 4.2.2. The slabs cured at room temperature for 28 days. All the slabs used a four point flexural test with a ctuator , [ Fig .4.1(c)] . Load and displacement were recorded by an additional load cell and a liner potentiometer. PI gauges recorded tension strain and pressure strain. D igital image correlation was also used to take pictures for the middle span of the slabs. 4.2 Material for Test Specimens 4.2.1 Glass Fiber Reinforced Polymer (GFRP) bars This test used No.3 GFRP bars with a 9.525 mm diameter and variou s length s . No.3 GFRP bar ’s cross section is 71.26 mm2 and it has ultimate tensile strength of 827 MPa with a tensile modulus of el asticity of 46 GPa. All the mechanical properties of a No.3 GFRP bar are shown in T able.4.2. The b ars ’ surface s are all s and/fabric coated which can increase by 40% the bond behavior between GFRP bars and concrete . The wood mold has dimensions of 1300 mm length by 304.8 mm width and 127 mm deep. Each slab has four GFRP bars inside. Each bar has 50.8mm concrete cover on each side. Plastic spacers were used to make sure the GFRP 60

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE bars were 25.4 mm above the bottom of the slabs. Steel wire was used to fix the bars position in the mold. T his test used a simple lap s plice a nd used No. 3 GFRP bars and steel wire to tie these two bars together [Fig .4.2.1(2)]. The s lab dimensions are 1300 mm length by 304.8 mm width and 127 mm deep. Used the formula from ACI 440.1R 06 g uide to the design the development length (ld) for FRP bars [14 ]. C is spacing or cover dimension (mm); db means diameter of reinforcing bar (mm); f’c r epresents specified compressive strength of concrete(MPa); f’fr means required bar stress(MPa) . ld is development length (mm); top bar modification factor. Diameter for the #3 GFRP bar is 9.525mm . ffr= 827MP a , this data is from the manufacture’s website. fc’=24Mpa from pervious cylinder tests us ing SAP /cement weight = 0%. C= db/2+H. H is the distance from the bottom of the bar to the bottom of the slab and is 25.4mm; db/2=9.525mm/2=4.7625; C=4.7625mm+25.4mm= 30.1625mm. This test has five different splice length s , 0.2ld=192mm; 0.4ld=384mm; 0.6ld=577mm; 0.8ld=769mm; 1.0ld=962mm. The slab length for this test is 1300mm.Depend on different ratio of splice length. GFRP bars also have different length [Fig .4.2] . 61

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE 1) When splice length is 0.2ld=192mm; Bar length is L1; X1= L1 0.2ld 0.2ld+2X1=1300mm X1=(1 300mm 192mm)/2=554mm L1=0.2ld+X1=192mm +554mm=746mm 2) When splice length is 0.4ld=384mm, Bar length is L2; X2= L2 0.4ld 0.4ld+2X2=1300mm X2 = (1300mm 384mm)/2=458mm L2 = 0.4ld+X2=384mm +458mm =842mm 3) When splice length is 0.6ld=577mm Bar length is L3; X3= L3 0.6ld 0.6ld+2X3=1300mm X3 = (1300mm 577mm)/2=361.5mm L3 = 0.6ld+X3=577mm +361.5mm =938.5mm 4) When splice length is 0.8ld=769mm, Bar length is L4; X4= L4 0.8ld 0.8ld+2X4=1300mm X4 = (1300mm 769mm)/2=265.5mm L4 = 0.8ld +X4=769mm +265.5mm =1034.5mm 5) When splice length is 1.0ld=962mm, Bar length is L5; X5= L5 1.0ld 62

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE 1.0ld+2X5=1300mm X5 = (1300mm 962mm)/2=169mm L5 = 1.0ld+X5=962mm +169mm =1131mm T his test need ed twelve #3 GFRP bars with a length of 746 mm; twelve #3 GFRP bars with a length of 842 mm; twelve #3 GFRP bars with a length of 938.5 mm; twelve #3 GFRP bars with a length of 1034.5 mm; twelve #3 GFRP bars with a length of 1131 mm. S teel wire was used to create a simple lap to tie the GFRP splices. 4.2.2 Concrete The 15 slabs were cast using 3 different concrete mix es . The concrete slab size is 1300 mm long, 304. 8mm inch wide, 127 mm inch deep. Each slab need ed 10.82 kg water, 22.44kg cement, 30.19kg sand, 55.08kg aggregate and vari ous amount s of SAP. All the materials need ed to be mixed in the correct order during the concrete mixing. A ggregate, sand and cement were mixed well first before adding water. After a dding water, the mix ture was well again. The last step was to add saturated SAP into the mixer and mix well again. This test used Portland Type 3 cement, cured for 28 days at room temperature. Portland Type 3 cement will let concrete strength increase in the first 7 days and the concrete strength will still increase a little bit before 28days. After 28 days, the concrete strength remain stable. The concrete slabs were tested after 28 days to make sure the concrete strength was not influence d by the number of days the concrete cured. The concrete was cast in a wooden mold. The wood is kiln dried c edar . Cedar is lightweight, therefore the mold is easy to move. Str ength and resistan ce to 63

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE decay are the most important characteristics of cedar. These two featu res can increase the mold ’s durability. These three types of Simpson Strong Tie s are used to connect the cedar wood: 113/16 in. x 5 in. tie plate, Z MAX 2 in. x 4 in. 12gauge galvanized medium L a ngle, and ZMAX 18 gauge galvanized steel angle . Three “U” shape steel hooks were placed in each beam. 24 hours after the concrete was cast, iron chain was placed into the three steel hooks. An overhead crane was used to lift the slabs out of the mold. After the mold was removed, plastic wrap was used to wrap the whole slab to resist effect s of external water, letting the SAP inside the concrete absorb the internal water only. Before test ing the slabs had white oil paint painted the middle span of the slabs. After the painted part dr ied , a dot brush roller was used to draw some clear black dots. These black dots made it easy for the DIC to catch the mov ement and analyze the strain on slabs. 4.2.3 Super Absorbent Polymer (SAP) SAP dosage ratio is based on the cement weight. This test has three differ ent SAP dosage ratio s 0%, 0.2%, and 0.4% S AP /cement weight. The more SAP used , the more water need s to be add ed . When SAP by cement weight is 0.2%, 0.04488kg SAP was needed per slab and an add itional 2044.08ml water was added for the SAP. When SAP by cemen t weight is 0.4%, 0.08976kg SAP was needed per slab and an add itional 4089.35ml water was added for the SAP. The water added for the SAP is different from the water in the concrete mix. The water for normal concrete mix helps the aggregate, sand and cement mix well. The water for the SAP is to saturate the SAP prior to its being added to the concrete mix. The following steps need to be followed when adding SAP to the concrete mix. First, weigh the SAP and then put SAP into a buck et . Second, weigh the amount of water for the SAP. The SAP absorbed all the water and 64

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE saturated in 7 minutes . Finally, add the saturated SAP to the mixer and combine well again. The water absorbed by the SAP releases during curing and helps the concrete’s internal curing. 4.2.4 Testing Tools An additional load cell was used to record the load and located in the middle of the steel frame and actuator . PI gauges were in the middle of the slab’s side. Before installing the PI gauges, glue was used to affix 4 nails to the side of the slab in the middle of the slab. The upper two nails were 25.4 mm from the top of the slab. The lower two nails were 25.4 mm from the bottom of the slab. Both sets of nails have a horizontal distance of 101.6 mm. Before testing, all the nails needed to cure for 24 hours to make sure the nails did not detach during the test. The linear potentiometer needed to be placed vertical to the bottom of slab. It was fixed under the middle span of the slabs. All the data from load cell, PI gauges and linear potentiometer were all collected by DATAQ. DIC was used to catch the pictures for the middle span of the slabs. DIC can generate grain scale digital image correlation [Fig.4.3(d)]. 4.3 Experimental Setup a nd Loading The following sections detail the test prepar ation , setup and method of loading for the experimental program. Also introduce d is the method of data collection. The l oad displacement behavior, loads train behavior and failure modes a re also included in this chapter. 65

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE 4.3.1. Setup This test is a four point flexure test. It has two supports and two loading points. Two steel strips were put on the loading points. A “U” shape steel frame was placed above the two loading points. The dis tance between the two loading points is 432 mm. The load cell was put on the steel frame. A flat steel plate was placed between the actuator and the load cell to ensure a stable force. The distance from each support to the end of the beam is 76.2 mm. Slabs will be loaded at a rate of 10 mm/min until the slabs fail. Digital i mage c orrelation (DIC) set up 3.5 meters away from the test slab. The DIC camera was kep t horizontal to the slab and focus ed on the middle span of the slab (white painting background wit h clear dark dots) 4.3.2 Load Displacement Behavior and Failure Modes Fig.4.4 show s concrete slabs’ ultimate load increased with splice length increase. Fig.4.5 show s concrete slabs’ ultimate load decreased with SAP amount increase. Load displacement behavior is shown in Fig .4.6 to 4.8. Failure mode s of slabs are shown in Fig .4.12 to 4.26 and s hows all fifteen concrete slabs’ failure mode with global and local pictures. The load carrying capacity did not show significant differen ce between 0.8ld and 0.6ld splice length . Based on failure mode pictures, shear failure crack happened between loading point and support point when splice length was 0.6ld, 0.8ld and 1.0ld. The failure crack shows the failure type is shear compression failure, which means concrete faile d before the GFRP bars yield. When s plice length was 0.2ld and 0.4ld, flexural failure crack usually happened in the end of splice length . 66

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE 4.3.3 Load Strain Behavior Concrete lab tension recorded by the down PI gauge and pressure was record by th e up PI gauge. Fig .4.9 to 4.11 show the load strain response of slabs with 0% SAP by vari ous GFRP splice length s, slabs with 0.2% SAP by various GFRP splice lengths, and slabs with 0.4 % SAP by various GFRP splice lengths. The splice lengths were 0.2ld; 0.4ld; 0.6ld; 0.8ld; 1.0ld. The up PI gauge was set up 25.4mm below the top of the slab on side of the middle span. The dow n PI gauge was set up 25.4mm below the bottom of the slab on side of the middle span. During the test, some PI gauges were dropped on the ground, Fig.4.9(e ). The down PI were drop ped when the load was applied. 67

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Table. 4.1Concrete Mix Proportions Material Dosage Water 205 kg/ m [12.8lb/ft] [1] Cement 446 kg/ m [27.8lb/ft] Sand 600 kg/ m [37.5lb/ft] Aggregate 1095 kg/ m [68.4lb/ft] SAP [2] Various [1] Type3 Portland cement (Highearly strength) [2] Different ratio for SAP Table. 4.2 Mechanical properties of #3 GFRP Bar Properties Value Nominal Diameter 9.525mm Cross sectional Area 71.26mm 2 Tensile Modulus of Elasticity, E f 46 GPa Guaranteed Tensile Strength, f* fu 827MPa Ultimate Tensile Load 58.72kN Ultimate Strength 0.0 179% Manufacturer’s data (Owens Corning Infrastructure Solutions, LLC) 68

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Table. 4.3Different Category Slabs for Test Two Splice Ratio SAP amount* 0.2l d =192mm 0% 0.2% 0.4% 0.4l d =384mm 0% 0.2% 0.4% 0.6l d =577mm 0% 0.2% 0.4% 0.8l d =769mm 0% 0.2% 0.4% 1.0l d =962mm 0% 0.2% 0.4% *: SAP amount= percentage of cement amount 69

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Ta ble. 4.4 Splice Length of GFRP bars Table. 4.5 Load carrying capacity of test specimens Bar Length, mm Splice Length, mm Slab Length, mm 1 L 1 = 746 mm 0.2l d = 192mm 1300mm 2 L 2 = 842 mm 0.4l d = 384mm 1300mm 3 L 3 = 938.5 mm 0.6l d = 577mm 1300mm 4 L 4 = 1034.5 mm 0.8l d = 769mm 1300mm 5 L 5 = 1131 mm 1.0l d = 962mm 1300mm 0%SAP 0.2%SAP 0.4%SAP 0.2ld 30.5kN 29.47kN 27.63kN 0.4ld 32.97kN 31.75kN 29.91kN 0.6ld 37.87kN 35.35kN 33.86kN 0.8ld 39.61kN 38.63kN 36.82kN 1.0ld 48.37kN 44.36kN 37.98kN 70

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE (a) L (Various) 50.8mm 1300mm 304.8mm 71

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE (b) (c) 50.8 mm 127 mm 304.8 mm 30.15 mm 4.75 mm 25.4 mm 72

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE (d) Fig.4.1 Specimen details: (a) reinforcing scheme; (b) cross section; (c) test setup; (d) pictur e 73

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE (a) (b) (c) Fig.4.2 Splice details: (a) variable splice length;(b) spacers; (c) placed bars(0.6ld) 74

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE (a ) (b) (c) 75

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE (d1) (d2) Fig.4 .3 Instrumentation: (a ) Load c ell;(b ) Liner potentiometer; (c ) PI gauge ;(d) DIC 76

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig. 4.4 Ultimate load of specimens (a) effect of splice length (b) comparison 0 10 20 30 40 50 0.0 0.2 0.4 0.6 0.8 1.0Load (kN)Splice length (ld) (a) 0%SAP 0.2%SAP 0.4%SAP 0 10 20 30 40 50 0.2 0.4 0.6 0.8 1Load (kN)Splice length (ld) (b) 0%SAP 0.2%SAP 0.4%SAP77

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig. 4.5 Ultimate load of specimens (a) effect of splice SAP (b) comparison 0 10 20 30 40 50 0.0 0.2 0.4Load(kN)SAP amount (%) (a) 0.2ld 0.4ld 0.6ld 0.8ld 1.0ld 0 10 20 30 40 50 0 0.2 0.4Load (kN)SAP amount (%) (b) 0.2ld 0.4ld 0.6ld 0.8ld 1.0ld78

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.6 Loaddisplacement of specimens with 0% SAP (a) 0.2ld; (b) 0.4ld; (c) 0.6ld; ( d) 0.8l d; ( e) 1.0l d; 0 10 20 30 40 50 0 10 20 30Load (kN)Displacement(mm) (a) 0 10 20 30 40 50 0 10 20 30Load (kN)Displacement(mm) (c) 0 10 20 30 40 50 0 10 20 30Load (kN)Displacement(mm) (d) 0 10 20 30 40 50 0 10 20 30Load (kN)Displacement(mm) (e) 0 10 20 30 40 50 0 10 20 30Load (kN)Displacement(mm) (b)79

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig. 4.7 Load displacement of specimens with 0 .2% SAP (a) 0.2ld; (b) 0.4ld; (c) 0.6ld; (d) 0.8ld; (e) 1.0ld 0 10 20 30 40 50 0 10 20 30Load (kN)Displacement(mm) (a) 0 10 20 30 40 50 0 10 20 30Load (kN)Displacement(mm) (b) 0 10 20 30 40 50 0 10 20 30Load (kN)Displacement(mm) (c) 0 10 20 30 40 50 0 10 20 30Load (kN)Displacement(mm) (d) 0 10 20 30 40 50 0 10 20 30Load (kN)Displacement(mm) (e) 80

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig. 4.8 Load displacement of specimens with 0 .4% SAP (a) 0.2ld; (b) 0.4ld; (c) 0.6ld; (d) 0.8ld; (e) 1.0ld 0 10 20 30 40 50 0 10 20 30Load (kN)Displacement (mm) (a) 0 10 20 30 40 50 0 10 20 30Load (kN)Displacement(mm) (b) 0 10 20 30 40 50 0 10 20 30Load (kN)Displacement(mm) (c) 0 10 20 30 40 50 0 10 20 30Load (kN)Displacement(mm) (d) 0 10 20 30 40 50 0 10 20 30Load (kN)Displacement(mm) (e) 81

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE 0 10 20 30 40 50 -0.002 0.000 0.002 0.004 0.006Load (kN)PI gauge (a) Up PI Down PI 0 10 20 30 40 50 -0.002 0.000 0.002 0.004 0.006Load (kN)PI gauge (b) Up PI Down PI 82

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE 0 10 20 30 40 50 -0.002 0.000 0.002 0.004 0.006Load (kN)PI gauge (c) Up PI Down PI 0 10 20 30 40 50 -0.002 0.000 0.002 0.004 0.006Load (kN)PI gauge (d) Up PI Down PI 83

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig.4.9 Loadstrain response of slabs with 0% SAP (a) 0.2ld; (b) 0.4ld; (c) 0.6ld; (d) 0.8ld; (e) 1.0ld 0 10 20 30 40 50 -0.002 0.000 0.002 0.004 0.006Load (kN)PI gauge (e) Up PI Down PI 84

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE 0 10 20 30 40 50 -0.002 0.000 0.002 0.004 0.006Load (kN)PI gauge (a) Up PI Down PI 0 10 20 30 40 50 -0.002 0.000 0.002 0.004 0.006Load (kN)PI gauge (b) Up PI Down PI 85

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE 0 10 20 30 40 50 -0.002 0.000 0.002 0.004 0.006Load (kN)PI gauge (c) Up PI Down PI 0 10 20 30 40 50 -0.002 0.000 0.002 0.004 0.006Load (kN)PI gauge (d) Up PI Down PI 86

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig.4.10 Loadstrain response of slabs with 0.2% SAP(a) 0.2ld; (b) 0.4ld; (c) 0.6ld; (d) 0.8ld; (e) 1.0ld 0 10 20 30 40 50 -0.002 0.000 0.002 0.004 0.006Load (kN)PI gauge (e) Up PI Down PI 87

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE 0 10 20 30 40 50 -0.002 0.000 0.002 0.004 0.006Load (kN)PI gauge (a) Up PI Down PI 0 10 20 30 40 50 -0.002 0.000 0.002 0.004 0.006Load (kN)PI gauge (b) Up PI Down PI 88

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE 0 10 20 30 40 50 -0.002 0.000 0.002 0.004 0.006Load (kN)PI gauge (c) Up PI Down PI 0 10 20 30 40 50 -0.002 0.000 0.002 0.004 0.006Load (kN)PI gauge (d) Up PI Down PI 89

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig.4.11 Loadstrain response of slabs with 0.4% SAP(a) 0.2ld; (b) 0.4ld; (c) 0.6ld; (d) 0.8ld; (e) 1.0ld 0 10 20 30 40 50 -0.002 0.000 0.002 0.004 0.006Load (kN)PI gauge (e) Up PI Down PI 90

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.12 Failure mode of slab with 0%SAP at 0.2ld 91

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.13 Failure mode of slab with 0%SAP at 0.4ld 92

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.14 Failure mode of slab with 0%SAP at 0.6ld 93

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.15 Failure mode of slab with 0%SAP at 0.8ld 94

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.16 Failure mode of slab with 0%SAP at 1.0ld 95

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.17 Failure mode of slab with 0.2%SAP at 0.2ld 96

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.18 Failure mode of slab with 0.2%SAP at 0.4ld 97

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.19 Failure mode of slab with 0.2%SAP at 0.6ld 98

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.20 Failure mode of slab with 0.2%SAP at 0.8ld 99

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.21 Failure mode of slab with 0.2%SAP at 1.0ld 100

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.22 Failure mode of slab with 0.4%SAP at 0.2ld 101

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.23 Failure mode of slab with 0.4%SAP at 0.4ld 102

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig4.24 Failure mode of slab with 0.4%SAP at 0.6ld 103

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.25 Failure mode of slab with 0.4%SAP at 0.8ld 104

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.26 Failure mode of slab with 0.4%SAP at 1.0ld 105

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.27 DIC images for slab with 0%SAP at 0.2ld 106

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.28 DIC images for slab with 0%SAP at 0.4ld 107

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.29 DIC images for slab with 0%SAP at 0.6ld 108

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.30 DIC images for slab with 0%SAP at 0.8ld 109

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.31 DIC images for slab with 0%SAP at 1.0ld 110

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.32 DIC images for slab with 0.2%SAP at 0.2ld 111

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.33 DIC images for slab with 0.2%SAP at 0.4ld 112

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.34 DIC images for slab with 0.2%SAP at 0.6ld 113

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.35 DIC images for slab with 0.2%SAP at 0.8ld 114

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.36 DIC images for slab with 0.2%SAP at 1.0ld 115

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.37 DIC images for slab with 0.4%SAP at 0.2ld 116

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.38 DIC images for slab with 0.4%SAP at 0.4ld 117

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.39 DIC images for slab with 0.4%SAP at 0.6ld 118

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.40 DIC images for slab with 0.4%SAP at 0.8ld 119

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CHAPTER IV SPLICE OF GFRP BARS EMBEDDED IN INTERNALLY CURED CONCRETE Fig .4.41 DIC images for slab with 0.4%SAP at 1.0ld 120

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CHAPTER V SUMMARY AND CONCLUSIONS CHAPTER V SUMMARY AND CONCLUSIONS 5.1 Summary and Conclusions The t est for the s trength of i nternally cured HPC r einforced with GFRP bars has a total of 15 slabs, 5 categ ories , and each category has 3 slabs. This test has 5 different SAP dosage ratios, 0%, 0.1%, 0.2%, 0.3% and 0.4% SAP by cement weight. A fourpoint test was used with actuator a fter 28 days of internal curing. 1. The test results show that with the increase of SAP /cement weight, the concrete slabs strength decreased. 2. The decrement rate for the load carrying capacity of slabs with different SAP/cement weight ratio was steady. The ultimate load for concrete slab reduced approximately 5 kN with an additional 0.1%SAP. 3. Diagonal tension failure happened to all the slabs. The concrete failed before GFRP bar s yield ed . T he t est for the splice of GFRP bars embedded in i nternally cured concrete total has 15 slabs. Three various amount s of SAP were tested (0%, 0.2%, 0.4% SAP b y cement weight) and five varied splice length s (0.2ld=192mm; 0.4ld=384mm; 0.6ld=577mm; 0.8ld=769mm; 1.0ld=962mm) were used in this test. The test used a four point test with actuator a fter 28 days of internal curing. 1. The t est result s show that , when the GFRP bars have the same splice length, the slabs’ failure load decreases with an increase of SAP/cement weight . 121

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CHAPTER V SUMMARY AND CONCLUSIONS 2. When SAP dosage is same, the slabs ’ failure load will increase with splice length increase. 3. Shear com pression failure happened to the slabs with 0.6ld, 0.8ld, 1.0ld splice length . The concrete failed before GFRP bar s yield ed . Flexural failure happened to the slabs with 0.4ld, 0.2ld splice length . 5.2 Recommendations for design Based on the results from chapter three and chapter four, better behavior can be seen when the SAP amount of 0.1% and 0.2% by cement weight was added. Compared with slabs without SAP, the failure load of concrete slabs reduced in an acceptable range. SAP also can provide extra water during the concrete curing period and reduce autogenous shrinkage for the HPC. When the GFRP bars splice length is 0. 2ld and 0.4ld, the failure mode of the concrete slabs was the same. The flexural cracks all happened near the middle span area. 5.3 Recommendations for Future Research To fully understand the strength of internally cured HPC r einforced with GFRP bars and the splicing of GFRP b ars embedded in internally cured concrete, more research is needed. The future research includes: 1. Increase the internal curing period to 6 mo nths or 12 months and, then evaluate the behavior of the GFRP bars embedded in concrete slabs with SAP. 122

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CHAPTER V SUMMARY AND CONCLUSIONS 2. Increase t he accuracy of the addition the SAP to 0.125%, 0.15% and 0.175%SAP/cement weight. Accurate SAP dosage is very necessary to consider the economic benefit of SAP. 3. Add more data points to the splice tests, by increasing the concrete slabs with various splic e lengths of the GFRP bars, by adding 0ld, 0.5ld, 0.1ld, 0.15ld, 0.25ld, 0.3ld and 0.35ld splice length. 4. Developing and testing the concrete slabs (embedded GFRP bars and add SAP) curing in different temperatures (summer and winter) and different humidity environments. 5. Size effect (cross section and length for the concrete slab) for GFRP bars embed ded in internal curing concrete. 123

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APPENDIX APPENDIX 0 10 20 30 40 50 600 10 20 30Load (kN)Displacement (mm) (a 1 ) 0 10 20 30 40 50 60 0 10 20 30Load (kN) Displacement (mm) (a 2 ) 0 10 20 30 40 50 600 10 20 30 Load (kN) Displacement (mm) (a 3 ) 0 10 20 30 40 50 60 0 10 20 30Load (kN)Displacement (mm) (b 1 ) 0 10 20 30 40 50 600 10 20 30Load (kN)Displacement(mm) (b 2 ) 0 10 20 30 40 50 600 10 20 30Load (kN) Displacement(mm) (b 3 ) 124

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APPENDIX 0 10 20 30 40 50 60 0 10 20 30Load (kN)Displacement(mm) (c 1 ) 0 10 20 30 40 50 60 0 10 20 30Load (kN)Displacement(mm) (c 2 ) 0 10 20 30 40 50 60 0 10 20 30 Load (kN) Displacement(mm) (c 3 ) 0 10 20 30 40 50 60 0 10 20 30Load (kN)Displacement(mm) (d 1 ) 0 10 20 30 40 50 60 0 10 20 30Load (kN) Displacement(mm) (d 2 ) 0 10 20 30 40 50 600 10 20 30Load (kN)Displacement(mm) (d 3 ) 125

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APPENDIX Appendix . (a1)(a2)(a3) 0%SAP Slabs ( b1)(b2)(b3)0.1%SAP Slabs ( c1)(c2)(c3)0.2%SAP Slabs ( d1)(d2)(d3)0.3%SAP Slabs ( e1)(e2)(e3)0.4%SAP Slabs 0 10 20 30 40 50 60 0 10 20 30Load (kN)Displacement(mm) (e 1 ) 0 10 20 30 40 50 60 0 10 20 30Load (kN) Displacement(mm) (e 2 ) 0 10 20 30 40 50 0 10 20 30Load (kN)Displacement(mm) (e 3 ) 126

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