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Record for a UF thesis. Title & abstract won't display until thesis is accessible after 2014-08-31.
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Language:
english
Creator:
Alsaffar, Adel
Publisher:
University of Florida
Place of Publication:
Gainesville, Fla.
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Thesis/Dissertation Information

Degree:
Doctorate ( Ph.D.)
Degree Grantor:
University of Florida
Degree Disciplines:
Design, Construction, and Planning Doctorate, Design, Construction and Planning
Committee Chair:
Nawari, Nawari Omer
Committee Co-Chair:
Muszynski, Larry C
Committee Members:
Kuenstle, Michael W
Issa, R. Raymond
Najafi, Fazil T

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Design, Construction and Planning -- Dissertations, Academic -- UF
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Design, Construction, and Planning Doctorate thesis, Ph.D.
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theses   ( marcgt )
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Statement of Responsibility:
by Adel Alsaffar.
Thesis:
Thesis (Ph.D.)--University of Florida, 2012.
Local:
Adviser: Nawari, Nawari Omer.
Local:
Co-adviser: Muszynski, Larry C.
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INACCESSIBLE UNTIL 2014-08-31

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lcc - LD1780 2012
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1 S TRUCTURAL BEHAVIOR OF LIGHTWEIGHT CONCRETE WALL PANELS IN TILT UP CONSTRUCTION By ADEL ALSAFFAR A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR T HE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2012

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2 2012 Adel Alsaffar

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3 To Allah for the support I have been blessed with and to my family

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4 ACKNOWLEDGMENTS Firstly, I am grateful to Allah for the support, guidan ce and love that I have been blessed with. I will always be your servant and will try my best to adhere to your teachings. I am also grateful to my role model, the messenger of Allah, Prophet Mohammad and his cousin Imam Ali and his daughter Lady Fatimah a nd to their decedents the eleven Imams. I would like to express my sincere regards and gratitude to my advisor and committee chairman Dr. Nawari Nawari. Thank you for your support and encouragement. You were always available to listen and provide advice. I grateful to my advisor and committee co chair Dr. Larry Muszynski for his support, technical guidance throughout this research project. I am also thankful to Dr. R. Raymond Issa, Dr. Fazel Najafi and Professor Michael Kuenstle for their support, gu idance, effort and feedback. Thank you for being a valuable part of this research. Your words of encouragement have helped me complete this project to its full potential. I would like to extend my appreciation to Kristina Lannon for assistance, effort and time throughout the process of this research. Your expertise, hard work and patience Hernacki from the Hernacki Company for your assistance and support. Your expertise and hard work was essential to the success of this research. I am thankful to the Department of Architecture at Kuwait University for giving me the opportunity to purse my higher education by providing me with the necessary means and support to achieve my Ph. D. degree. My dear wife Alyaa and wonderful sons Adnan and Ali, thank you for your support and understanding. Without your love and patience I would not been able to succeed in

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5 my journey. My father Mahdi and mother Fati mah, thank you for your support and trust. Your teachings have gone a long way for me. I forever grateful to you and love you with all of my heart. My brothers and sisters, thank you for your words of encouragements. To the rest of my family, thank you for your trust in me. I would like to a lso thank the companies for their donations and support. This research project would have been difficult to complete without your assistance and contributions. Thank you Florida Rock Industries, FHWA/Mobile Concrete Laboratory Vishay Micro Measurements, En gius, Meadow Burke, Gerdau AmeriSteel, Dayton Superior, BNG Construction and Germann Instruments.

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6 TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................ ................................ ................................ .. 4 LIST OF TABLES ................................ ................................ ................................ .......... 10 LIST OF FIGURES ................................ ................................ ................................ ........ 12 ABSTRACT ................................ ................................ ................................ ................... 17 CHAPTER 1 INTRODUCTION ................................ ................................ ................................ .... 19 Definition of Tilt up Walls ................................ ................................ ........................ 19 Background ................................ ................................ ................................ ............. 19 Research Objectives ................................ ................................ ............................... 20 Research Approach ................................ ................................ ................................ 20 Research Significance ................................ ................................ ............................ 21 Dissertation Outline ................................ ................................ ................................ 22 2 LITERATURE REVIEW ................................ ................................ .......................... 23 History of Tilt Up ................................ ................................ ................................ ..... 23 Structural Lightweight Concre te ................................ ................................ .............. 25 Background ................................ ................................ ................................ ...... 25 Economy of Lightweight Concrete ................................ ................................ .... 26 Lightweight Aggregates ................................ ................................ .................... 26 Fire Resistance ................................ ................................ ................................ 27 Internal Curing ................................ ................................ ................................ .. 27 Modulus of Elas ticity ................................ ................................ ......................... 28 Modulus of Rupture ................................ ................................ .......................... 29 Tilt up and Lightweight Structural Concrete ................................ ............................ 29 Maturity ................................ ................................ ................................ ................... 30 Nurse Saul Maturity Method ................................ ................................ ............ 31 Equivalent Age ................................ ................................ ................................ 31 COMA Meter ................................ ................................ ................................ .... 32 Pullout ................................ ................................ ................................ ..................... 33 Strains and Stresses in Tilt up Panels ................................ ................................ .... 34 3 RESEARCH METHODOLOGY ................................ ................................ ............... 44 General Introduction ................................ ................................ ............................... 44 Concrete Mixture Design ................................ ................................ ........................ 44 Cement ................................ ................................ ................................ ............. 45 Air Entrained Agent ................................ ................................ .......................... 45

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7 Water Reducer ................................ ................................ ................................ 46 Co arse Aggregates ................................ ................................ .......................... 46 Fine Aggregate ................................ ................................ ................................ 46 Preparation of Concrete Specimens ................................ ................................ ....... 46 Concrete Cylinders ................................ ................................ ........................... 47 Concrete Beams ................................ ................................ ............................... 48 Tests on Fresh Concrete ................................ ................................ ........................ 48 Slump of Hydraulic Cement Concrete ................................ .............................. 48 Air Content of Freshly Mixed Concrete by Volumetric Method ......................... 4 9 Unit Weight ................................ ................................ ................................ ....... 50 Temperature Test ................................ ................................ ............................. 50 Tests on Hardened Concrete ................................ ................................ .................. 51 Compression Test ................................ ................................ ............................ 51 Third Point Flexure Test ................................ ................................ ................... 52 Maturity Method ................................ ................................ ................................ ...... 52 Maturity Method Process ................................ ................................ .................. 53 Evaluating the Strength of Concrete Using Temperature Time Factor ............. 53 Evaluating the Strength of Concrete Using the Equivalent Ag e Method ........... 54 Maturity Measurement Device ................................ ................................ .......... 54 Pullout Strength Method ................................ ................................ ......................... 55 Strain Measurements ................................ ................................ .............................. 56 Strain Gauge Installation ................................ ................................ .................. 56 Surface preparations ................................ ................................ .................. 56 Gauge bonding ................................ ................................ .......................... 57 Data Acquisition System ................................ ................................ ................... 57 4 MATURITY METHODS ................................ ................................ ........................... 76 Strength Maturity Relationship ................................ ................................ ................ 76 Temperature Time Factor (TTF) ................................ ................................ ....... 76 Compressive strength TTF relationship ................................ ..................... 76 Flexural strength TTF relationship ................................ ............................. 77 Equivalent Age (EA) ................................ ................................ ......................... 77 Compressive stren gth Equivalent Age relationship ................................ ... 78 Flexural strength Equivalent Age relationship ................................ ........... 78 Evaluation of Strength Maturity Relationship ................................ .......................... 79 Evaluating Temperature Time Factor Method ................................ .................. 79 Evaluating compressive strength TTF relationship ................................ .... 79 Evaluating flexural strength TTF relationship ................................ ............. 79 Evaluating Equivalent Age Method ................................ ................................ ... 80 Evaluating compressive strength EA relationship ................................ ...... 80 Evaluating flexural strength EA relationship ................................ .............. 80 Evaluating COMA Meter ................................ ................................ ................... 81 5 PULLOUT METHOD ................................ ................................ ............................... 99 Strength Pullout Relationship ................................ ................................ ................. 99

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8 Compressive Strength Pullout R elationship ................................ .................... 99 Flexural Strength Pullout Relationship ................................ .......................... 100 Evaluation of Strength Pullout Relationship ................................ ......................... 100 Evaluating Compressive Strength Pullout Relationship ................................ 100 Evaluating Flexural Strength Pullout Relationship ................................ ......... 101 6 MATURITY AND PULLOUT STRENGTH ................................ ............................. 112 Pullout Strength Maturity Relationship ................................ ................................ .. 112 Pullout Strength TTF ................................ ................................ ...................... 112 Pullout strength TTF compressive strength ................................ ............. 112 Pullout strength TTF flexural strength ................................ ...................... 113 Pullout Strength Equivalent Age (EA) ................................ ............................ 113 Pullout strength EA compressive strength ................................ ............... 113 Pullout strength EA flex ural strength ................................ ....................... 113 Evaluation of Pullout Strength Maturity ................................ ................................ 114 Pullout Strength TTF Verification ................................ ................................ ... 114 Pullout strength TTF compressive strength verification ......................... 114 Pullout strength TTF flexural strength verification ................................ ... 114 Pullout Strength EA Verification ................................ ................................ ..... 115 Pullout strength EA compressive strength verification ............................ 115 Pullout strength EA flexural strength verification ................................ ..... 115 7 TILT UP PANEL DESIGN AND CONSTRUCTION ................................ .............. 126 Overview ................................ ................................ ................................ ............... 126 Panel Design ................................ ................................ ................................ ........ 126 Statics Computations ................................ ................................ ............................ 126 Angle of Inclination ................................ ................................ ......................... 127 Moment Computations in the Y Y Direction ................................ .................... 127 Stresses Computations in the Y Y Direction ................................ ................... 128 Moment Co mputations in the X X Direction ................................ .................... 129 Stresses Calculations in the X X Direction ................................ ..................... 130 Statics Computations Using 1.5 Suction Factor ................................ .................... 131 Moment Computations in the Y Y Direction with Suction ............................... 131 Stresses Computations in the Y Y Direction with Suction .............................. 131 Moment Computations in the X X Direction with Suction ............................... 131 Stresses Calculations in the X X Direction with Suction ................................ 132 ................................ ................................ ............................. 132 Casting Mud Slab ................................ ................................ ........................... 132 Formwork and Steel Reinforcement ................................ ............................... 133 Lifting Inserts ................................ ................................ ................................ .. 133 Bond Breaker ................................ ................................ ................................ 134 Tilt up Panel Casting ................................ ................................ ...................... 134 Strain Gauges Location ................................ ................................ .................. 135 Lifting of Tilt up Panel ................................ ................................ ........................... 135

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9 8 STRESS AND STRAIN ANALYSIS OF TILT UP PANEL DURING LIFTING ....... 157 Overview ................................ ................................ ................................ ............... 157 Critical Angle of Inclination ................................ ................................ .................... 157 Field Strains Collection ................................ ................................ ......................... 157 Modulus of Elasticity ................................ ................................ ............................. 158 Converting Strains to Stresses ................................ ................................ ............. 159 Stresses Comparison ................................ ................................ ............................ 159 Stresses Lightweight versus Normal Concrete ................................ ..................... 160 9 CONCLUSI ONS AND RECOMMENDATIONS ................................ ..................... 169 Conclusions ................................ ................................ ................................ .......... 169 Recommendations ................................ ................................ ................................ 170 APPENDIX A TEMPERATURE AND TIME DATA RECORDED BY MATURITY LOGGERS ..... 171 B COMMERCIAL SOFTWARE RESULTS ................................ ............................... 178 Commercial Software 1 ................................ ................................ ......................... 178 Commercial Software 2 ................................ ................................ ......................... 181 C DESIGN COMPARISON OF LIGHTWEIGHT AND NORMAL WEIGHT CONCRETE TILT UP WALL PANELS ................................ ................................ 184 Load Case 1: 1.2 D + 1.6 Lr + 0.8 W ................................ ................................ .... 184 Load Case 2: 1.2D + 0.5 Lr + 1.6W ................................ ................................ ..... 185 Load Cas e 3: 0.9D + 1.6W ................................ ................................ ................... 186 LIST OF REFERENCES ................................ ................................ ............................. 187 BIOGRAPHICAL SKETCH ................................ ................................ .......................... 18 9

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10 LIST OF TABLES Table page 3 1 Mix Design for structural lightweight concrete (H65BC) ................................ ..... 58 3 2 Chemical and physical properties of type I & type II cemen t .............................. 59 3 3 Properties of Lightweight Coarse Aggregate ................................ ...................... 61 3 4 Properties of the Florida Rock Industries fine aggregate ................................ .... 62 3 5 Concrete specimens, control batch ................................ ................................ .... 62 3 6 Concrete specimens, experimental batch ................................ ........................... 62 3 7 Air content measurement ................................ ................................ ................... 67 3 8 IntelliRock temperature loggers specifications ................................ ................... 69 3 9 IntelliRock II Reader specificat ions ................................ ................................ ..... 69 3 10 D4 data acquisition conditioner specifications ................................ .................... 75 4 1 Control batch TTF and compressive strength ................................ ..................... 82 4 2 Control batch TTF and flexural strength ................................ ............................. 84 4 3 Equivalent age and compressive strength ................................ .......................... 86 4 4 Equivalent age and flexural strength ................................ ................................ .. 88 4 5 Compressive strength TTF verification, experimental batch. .............................. 90 4 6 Flexur al strength TTF verification, experimental batch ................................ ....... 92 4 7 Compressive strength EA verification, experimental batch ................................ 94 4 8 Flexural s trength EA verification, experimental batch. ................................ ..... 96 4 9 COMA Meter and Equivalent Age ................................ ................................ ....... 98 5 1 Pull force and compressive strength ................................ ................................ 103 5 2 Pull force and flexural strength ................................ ................................ ......... 105 5 3 Compressive strength and pullout, experimental batch ................................ .... 108 5 4 Flexural strength and pullout, experimental batch ................................ ............ 110

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11 6 1 Pullout strength TTF control batch ................................ ................................ 116 6 2 Pullout stregth EA control batch ................................ ................................ ..... 119 7 1 Physical and Chemical Properties of J6WB Sure Lift by Dayton Superior. ....... 151 8 1 Maximum strain at zero degree of inclination ................................ ................... 164 8 2 Stresses calculations ................................ ................................ ........................ 165 8 3 Stress comparison of lightweight concrete tilt up panel ................................ .... 166 8 4 Stress comparison of lightweight versus normal concrete ................................ 167 C 1 Tilt up panel design comparison for load ca se 1 ................................ .............. 184 C 2 Tilt up panel design comparison for load case 2 ................................ .............. 185 C 3 Tilt up panel design comparison for load case 3 ................................ .............. 186

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12 LIST OF FIGURES Figure page 2 1 Tipping table use in tilt up construction ................................ .............................. 36 2 2 La Jolla Wome ................................ ................................ ....................... 36 2 3 ................................ ................................ ............................... 37 2 4 Fire rating for various densities of concrete ................................ ........................ 37 2 5 Normal vs. lightweight concrete curing characteristics ................................ ....... 38 2 6 Modulus of elasticity of different densities of concrete ................................ ........ 38 2 7 Normal vs. lightweight concrete modulus of elasticity ................................ ......... 39 2 8 Modulus of rupture for d ifferent densities of concrete ................................ ........ 39 2 9 Wall design model ................................ ................................ .............................. 40 2 10 Panel self weigh ................................ ................................ ................................ 40 2 11 Temperature Time Factor ................................ ................................ ................... 41 2 12 Thermal history curve ................................ ................................ ......................... 41 2 13 Age conversion factor according to activation energy ................................ ........ 42 2 14 COMA m aturity meter ................................ ................................ ......................... 42 2 15 Cross section of pullout test ................................ ................................ ............... 43 2 16 Principle of pullout test ................................ ................................ ....................... 43 3 1 Concrete curing tank ................................ ................................ .......................... 63 3 2 Rodding cylinder specimen ................................ ................................ ................ 63 3 3 Concrete cylinders with pullout inserts ................................ ............................... 64 3 4 COMA meter pressed in concrete cylinders ................................ ....................... 64 3 5 Temperature loggers in cylinders and beams ................................ ..................... 65 3 6 Slump test cone ................................ ................................ ................................ .. 65 3 7 Slump test scheme ................................ ................................ ............................. 66

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13 3 8 Air meter by volumetric method ................................ ................................ .......... 66 3 9 Adding isopropyl alcohol to prevent foaming ................................ ...................... 67 3 10 Measuring the temperature of concrete ................................ .............................. 68 3 11 FORNEY compressive test machine ................................ ................................ .. 68 3 12 ................................ ................................ ... 69 3 13 Location of pull insert (disc) in the concrete ................................ ....................... 70 3 14 Pullout fracture in a shape of a cone ................................ ................................ .. 70 3 15 Cylinder pullout insert with floating cup ................................ .............................. 71 3 16 ................................ ........................ 71 3 17 Pullout process ................................ ................................ ................................ ... 72 3 18 Surface preparation ................................ ................................ ............................ 73 3 19 Gauge bonding procedure ................................ ................................ .................. 74 3 20 D4 data acquisition conditioner ................................ ................................ ........... 75 4 1 Compressive Strength TTF Relationship ................................ ............................ 83 4 2 Flexural Strength TTF Relationship ................................ ................................ .... 85 4 3 Comp ressive Strength Equivalent Age Relationship ................................ ........ 87 4 4 Flexural Strength Equivalent Age Relationship ................................ ................. 89 4 5 Verification of Compre ssive strength TTF relationship, experimental batch ...... 91 4 6 Verification of flexural strength TTF relationship, experimental batch ............... 93 4 7 Verification of compressive strength EA relationship, experimental batch ......... 95 4 8 Verification of flexural strength EA relationship, experimental batch ................. 97 5 1 Radial cracking on cylinder due to pull force. ................................ ................... 102 5 2 Encased cylinder during pullout testing ................................ ............................ 102 5 3 Compressive strength pullout relationship ................................ ....................... 104 5 4 Flexural strength pullout relationship ................................ ............................... 106

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14 5 5 Cracking outside the t esting area tilt up panel side ................................ ......... 107 5 6 Pullout insert, tilt up panel surface ................................ ................................ .... 107 5 7 Verification of compressive strength pullou t relationship ................................ 109 5 8 Verification of flexural strength pullout relationship ................................ ......... 111 6 1 Pullout strength TTF compressive strength relationship, control batch ........... 117 6 2 Pullout strength TTF flexural strength relationship, control batch .................... 118 6 3 Pullout stregth EA compressive strength relationship, control batch ................ 120 6 4 Pullout stregth EA flexural strength relationship, control batch ........................ 121 6 5 Verification of pullout strength TTF compressive strength relationship, experimental batch ................................ ................................ ........................... 122 6 6 Verification of pullout strength TTF flexural strength relationship, experimental batch ................................ ................................ ........................... 123 6 7 Verification of pullout strength EA compressive strength relationship, experimental batch ................................ ................................ ........................... 124 6 8 Verification of pullout stren gth EA flexural strength relationship, experimental batch ................................ ................................ ................................ ................. 125 7 1 Tilt up panel dimensions ................................ ................................ ................... 136 7 2 Angle of inclination ................................ ................................ ........................... 137 7 3 Tilt up panel sections to calculate moments in Y Y direction ............................ 138 7 4 Shear and moment diagram of tilt up panel at zero degree in Y Y direction .... 139 7 5 Maximum moments Y Y direction, at zero degree due to lifting ........................ 140 7 6 Tilt up panel sections to calculate moment s in X X direction ............................ 141 7 7 Shear and moment diagram of tilt up panel at zero degree in Y Y direction .... 142 7 8 Maximum moments X X d irection, at zero degree due to lifting ........................ 143 7 9 Shear and moment diagram, Y Y direction with suction ................................ ... 144 7 10 Shear and moment dia grams, X X direction with suction ................................ 145 7 11 Casting bed preparations ................................ ................................ ................. 146

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15 7 12 Tilt up panel formwork ................................ ................................ ...................... 146 7 13 Steel reinforcement design ................................ ................................ ............... 147 7 14 Steel reinforcement levels ................................ ................................ ................ 147 7 15 Tilt up panel st eel reinforcement ................................ ................................ ...... 148 7 16 Lifting inserts and reinforcement ................................ ................................ ....... 149 7 17 Bond breaker being sprayed ................................ ................................ ............. 150 7 18 Casting tilt up panel ................................ ................................ .......................... 152 7 19 Maturity logger and pullout insert at 3.17 feet ................................ ................... 152 7 20 COM A meter being inserted into the fresh concrete ................................ ......... 153 7 21 Strain gauges locations ................................ ................................ .................... 154 7 22 Stain gauge data acquisition devices link s to a computer ................................ 155 7 23 Tilt up lifting process ................................ ................................ ......................... 156 8 1 Surface mount strain gauge locations ................................ .............................. 163 8 2 Strain measurements during tilt up panel lifting ................................ ................ 164 8 3 Modulus of elasticity test ................................ ................................ .................. 165 8 4 Str ap cables lifting at 45 degree angle ................................ ............................. 166 8 5 Tilt up panel stress comparison ................................ ................................ ........ 167 8 6 Stress comparison of lightweight versus norma l concrete ................................ 168 A 1 Temperature vs. Time of logger embedded in beam 1, control batch ............... 171 A 2 Temperature vs. Time of logger embedde d in beam 2, control batch ............... 172 A 3 Temperature vs. Time of logger embedded in cylinder 1, control batch ........... 173 A 4 Temperature vs. Ti me embedded in cylinder 2, control batch .......................... 174 A 5 Temperature vs. Time of logger embedded in cylinder 1, experimental batch 175 A 6 Temperature vs. Time of logger 1 embedded in tilt up wall panel, experimental batch ................................ ................................ ........................... 176

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16 A 7 Temperature vs. Time of logger 2 embedded in tilt up wall panel, experimental batch ................................ ................................ ........................... 177

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17 Abstract of Dissertation Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy S TRUCTURAL BEHAVIOR OF LIGHTWEIGHT CONCRETE WAL L PANELS IN TILT UP CONSTRUCTION By Adel Alsaffar August 2012 Chair: Nawari O. Nawari Cochair: Larry C. Muszynski Major: Design, Construction and Planning In tilt up wall construction, normal weight concrete is usually poured on top of a floor slab, an d then lifted into place by cranes when the wall gains an adequate strength Prior to lifting a panel, it is required by the ACI 551 .2R 10 guide and the inserts manufacturers that compressive and flexural strengths of the concrete testing are performed on samples retained in the field to validate that the wall has attained the required strength. In this study, the commonly used normal weight concrete in tilt up constructions was replaced with structural lightweight concrete for its advantageous properties. Furthermore, non destructive testing methods m aturity and p ullout tests were applied to evaluate the strength of concrete at early age. Although all maturity methods were found to be an effective tool to predict the compressive and flexural strengths of in place concrete at time of lifting the equivalent age maturity method was found to be superior to the temperature time factor maturity method. The p ullout strength method was also used to evaluate th e in place compressive and flexure strength s of the t ilt up wall and was found effective

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18 Hence, relationships between the various maturity methods and the pullout strength were derived to provide a better method of estimating the compressive and flexural strength of the lightweight concrete. In addition, a small scale tilt up panel (10 feet by 9 feet ) was constructed with surface mount strain gages in order to examine the strains and stresses of the p anel during lifting. The measured strains and stresses were compared to those obtained from statics calcula tions and two commercial software programs They were also compared to strains and stresses of a normal weight concrete.

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19 CHAPTER 1 INTRODUCTION Definition of Tilt up Walls Tilt up is a method for constructing concrete walls that have been cast horizonta lly floor or a temporary concrete casting surface near the building The walls are lifted by cranes to their final position in the structure when the concrete reaches or exceeds the specified co mpressive and flexural strength as i nterior or exterior load baring walls. Basically, it is a method of site cast ing precast concrete walls. The ACI committee 551 defines the Tilt concrete elements in a horizontal position at the jobsite and then t ilting them to thei r final position in a structure ( ACI.551 2010 ) Background Due to the numerous benefits of tilt up construction, it is one of the fast growing construction methods in the world. In 2007, approximately 790 million square feet of tilt up buildings were constructed based on a survey conducted by the Til t Up Concrete Association. ( TCA 2011 ) The ACI 551 committee report C oncrete Tilt Up indicates that the compressive and tensile strength of the concrete are major factors in designing tilt up walls. It states that a minimum concrete compressive strength of 3000 psi is required at 28 days. Also the lifting inserts manufacturers cal l for a compressive strength of 2500 psi at the day of lift; thus a higher 28 day compressive strength is normally desired. In addition, a minimum flexural strength of concrete of 400 500 psi is normally specified to prevent flexural cracking during liftin g. ( ACI.551 2010 )

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20 Another major design factor in tilt up walls is the self weight or dead load of the panel The self weight represents a significant contribution to internal forces and the P The self weight of the wall upper half is considered an axial load s acting downwards on the wall. Research Objectives The Scope of the project is to investigate the strength and behavior of the lightweight concrete ti lt up panels The objectives of this research are mainly: 1. Study the overall structural effectiveness of the lightweight concrete in tilt up construction 2. Estimate t he compressive and flexural s trength s of lightweight c oncrete tilt up panel using Temperatur e Time Factor (TTF) maturity method also known as Nurse Saul maturity method. 3. Estimate the compressive and flexural s trength s of lightweight c oncrete tilt up panel using Equivalent Age (EA) maturity method based on Arrhenius equation. 4. Estimate the compress ive and flexural s trength s of lightweight c oncrete tilt up panel using pullout strength test 5. Determine new correlation formulas between the compressive and flexural strength s of lightweight concrete tilt up panel by performing maturity testing and pullout testing 6. Determine the act ual strains and stresses developed in tilt up wall panel during lifting and compare them to stresses obtained from statics calculations and commercial software 7. Compare the resu lts of the lightweight concrete tilt up panel to a normal density concrete panel 8. Provide recommendations for the lightweight concrete tilt up walls. Research Approach Compressive and flexural strengths of concrete are determined using different mechanica l t est methods that require the breaking of sample concrete cylinders and beams. In this research, semi destructive and non destructive tests were utilized to

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21 evaluate the strength of concrete used in tilt up wall s construction for a specific lightweight concrete mix design In addition, a tilt up panel was designed and constructed with a lightweight concrete. The wall was instrumented with surface mount strain gages to measure the strains where the maximum negative and positive bending moments are expected due to lifting. The stresses due to lifting were compared with the statically calculated stresses and stresses obtained from two commercial software programs The strains and stresses were also compared with those of the normal density concrete to determine the structural efficiency of using lightweigh t concrete in tilt up construction. The following tests were conducted: Compressive strength ( ASTM C39 2011a ) Flexural strength ( ASTM C78 2010 ) Temperature Time Factor Maturity Method ( ASTM C1074 2011 ) Equivalent Age Maturity Method ( ASTM C1074 2011 ) Pullout strength ( ASTM C900 2006 ) Density of c oncrete ( ASTM C567 2005a ) Slum p test ( ASTM C143 2005 ) Air content ( ASTM C173 2001 ) Res earch Significance The application of structural lightweight concrete in tilt up walls seems more logical than the use of normal weight concrete due to its advantageous lightweight properties. Yet there has not been any study on the structural effectivenes s of structural lightweight concrete for tilt up applications. Furthermore, the use of various nondestructive and semi destructive methods of estimating concrete compressive and flexural strengths reflects onsite strengths of concrete rather than a lab cur ed test specimens. This research investigated the use of

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22 multiple methods of evaluating the strength of concrete to reach a higher level of confidence. Dissertation O utline Chapter 1 covers a general introduction to tilt up construction, research objective s, approach and significance. Review of literature is summarized in Chapter 2 with an overview of the history of tilt up walls construction. It also includes structural lightweight concrete mix design specifications and their advantages. In addition, diffe rent maturity methods are discussed followed by the pullout strength test and strain ga u ging concrete structur al elements Chapter 3 demonstrates the testing methodology for fresh an d hardened concrete as well as lightweight concrete mix design. It also ou tlines the different methods used to estimate the strength of the lightweight concrete. D ifferent maturity methods and pullout tests were analyzed in C hapters 4 and 5 respectively. Maturity methods and pullout strength relationships are discussed in C hapte r 6 Chapter 7 demonstrates the tilt up wall design and construction in addition to the behavior of the tilt up panel during lifting. It also includes calculations of bending moments developed due to lifting Chapter 8 examines the strain patterns of the l ightweight concrete tilt up wall. It analysis the stresses and compare them to the expected results. Also, a comparative study on the strength and stiffness of lightweight versus normal density concrete is conducted Chapter 9 draws conclusions and gives r ecom mendations for future studies.

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23 CHAPTER 2 LITERATURE REVIEW History of Tilt Up Tilt up construction is a very old trade. It was 2 000 years ago that Roman builders discovered that tilting up a wall after casting it horizontally on the ground is a much practical than pouring concrete walls in formwork and t hen stripping them (TCA, 2006) In the US Camp Logan, IL was the first known structure built with the modern tilt up construction techniques. It was constructed in 1893 by Robert H. Aiken who is know n as the father of tilt up He poured reinforced concrete walls horizontally on a flat surface and used t ipping tables to place them into their final position in the structure. Other projects followed namely, t he Memorial United Methodist Church of Zion, IL built 1906 and the Camp Perry Commissary Building, OH built i n 1908 by Aiken stand witness of the durability of the tilt up construction metho d ( Superior 2009 ) Maura Johnson, an architectural historian, claims that the Camp Perry Mess Hall was the first permanent structure constructed using the tilt up construction method in 1909. It was constructed using tipping tables with supporting jacks 3 feet of f the ground. The tables were positioned in a way that the walls were tipped into their permanent locations when the tables are raised ( Figure 2 1 ) Aiken utilized a 5 horsepower engine to swing the tipping tables that were removed after the walls are braced. He also built a concrete k and ( Johnson 2002 ) Irving Gill, up patent when he went bankrupt during t he construction of Camp Perry. Gill was

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24 influenced by Adler & Sullivan when he worked with them during his early career. He took the tilt up constr uction system to a higher level by applying great artistic expression. Gill used the same table tipping technique to build Club in 1914. He designed the porch are using arches to contrast sunlight with shadows and shadings ( Figure 2 2 ) ( TCA 2011 ) Another early example of innovation of tilt up is the Schindle r House also known as Kings Road House completed in 1922 Rudolf M Schindler became familiar with the were considered the modern landmarks of the modernist movement. "In his own house, Schindler expressed his philosophy about structure and materials most clearly, but the entire site demonstrates his exploration of the relationship of space, light, and form." ( Greatbuildings.com ) The design of the Kings Road House employed a 4ft wide tilt up panel which was building system. After many discussions, the building departm ent agreed under the condition of suspending the construction at any point. Schindler agreed on the condition which resulted on an iconic design, one of the first modernist homes in southern California ( Figure 2 3 ) ( Greatbuildings.com 2012 ) The tilt up industry deteriorated during the World War I due to the shortage of manpower and steel. Past World War II, major developments to the tilt up system indust ry came with the availability of heavy cranes that were able to haul larger sections of walls O ther factor s were the huge demand for warehouses and manufacturing plants which were typical and ideal for tilt up construction during the mid of the 20 th centu ry.

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25 The tilt up industry grew from $2 million in 1946 to $180 million in 1952 ( TCA 2011 ) Nowadays, t ilt up construction is a fast inexpensiv e method of constructing any low rise building. In the 2007 survey conducted by the Tilt Up Concrete Association (TCA), approximately 790 million square feet of tilt up structure were built in that year and 15% of al l low rise commercial and industrial were constructed with tilt up system. ( TCA 2011 ) Structural Ligh tweight Concrete The ACI Committee 213 defines the structural lightweight concrete as the concrete with a minimum compressive str ength of 2500 psi at 28 days with a density of 70 120 pounds per cubic feet. It may entirely consist of lightweight aggregate o r a combination of li ght and normal weight aggregate. Background Lightweight concrete can be dated back to over 2000 years ago. The lightweight concrete structures were use d during the early Roman Empire. For example, the Pantheon, and the Coliseum, n atur al volcanic materials were crushed and used in the making of lightweight concrete. The Pantheon, completed in 27 B.C., used concrete with different densities in different section of the dome. The Coliseum foundations, built in 75 to 80 A.D., were cast with the fall of the Roman Empire, the use of lightweight concrete was limited until the 20th century when a new type of manufactured, expanded shale, lightweight aggregate became available for commercia l use ( ACI.213 2003 ) The rotary kiln process of expanding slate, s hale and clay was patented in 1918 by Stephen J. Hayde, who was a brick manufacturer and ceramic engineer However, the e xpanded slag became commercially available in 1928, wherea s the sintered shale

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26 lightweight aggregate became available in 1948. During t he 1950s, many multistory buildings were entirely designed using lightweight concrete taking advantage of the reduced dead weight. ( ACI.213 2003 ) Economy of L ightweight C oncrete Generally, the cost of the lightweight concrete per cubic yard is higher than same strength normal weight concrete. However, the extra cost can b e offset by the reduction in dead loads which would result in smaller foundations and other structural elements such as beams, girders, slabs, staircases, shear walls and columns In addition to its fire resistance and acoustic advantages, t he use of light weight concrete is also beneficial for thermally sensitive applications like water tanks nuclear reactors, petroleum storage s or building insulation s Lightweight Aggregates C ellular pore syst em and air voids of the lightweight aggregate keep the relative density of the particles low The Heating of certain raw materials at high temperatures makes gases escape causing expansion in the raw m aterials. Structural l ightweight aggregate s should conform to the Standard Specification for Lightweight Aggregates fo r Structural Concrete ( ASTM C330 2009 ) They should also contain a uniformly distributed system of por es ranging from 5 to 300 m in size. Surface pores are permeable and can be saturated in the first few hours of the introduction of moisture. On the other hand, internal pores sat urate slowly, it could take several months of submerging to reach full saturation Generally a small fraction of interior pores are not inter connected and remain dry even after years of submerging Also, shape and texture of lightweight aggregates may con siderably differ due to different sources, or different production methods. This may affect the proportioning of

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27 mixtures which affect workability, pumpa bility fine to coarse aggregate ratio, and water requirement. ( ACI.213 2003 ) Fire Resistance Thermal conductivity is directly proportional to thermal diffusivity, specifi c heat and density. Conductivity and diffusivity variation is relatively small in specific heat with temperature. However the density of the concrete is the overall important variable due to air voids. Thus, lightweight concrete is superior in heat resista nce as compare with normal concrete and has significa ntly lower thermal conductivity and thermal expansion. Figure 2 4, illustrates the fire endurance of different density concrete. Internal C uring The ACI committee 308 Guide to Curing Concrete, defines by which hydraulic cement concrete matures and develops hardened properties over time as a result of the continued hydration of the cement in the presence of sufficient ( ACI.308 2001 ) Curing process should be made available as soon as the finishing of concrete is completed. In the standard curing for normal weight concrete, moisture is applied to the concrete surface only In addition to the surface curing lightweight concrete is characterized by internal curing; where i nternal c uring is defined by ACI 213 as the process by which the hydration of cement con tinues due to the availability of internal water ( ACI.213 2003 ) M ost expanded lightweight aggregates have the ability to absorb 15% or more water by weight. The absorbed water is readily available to hydrate cement deprived of water especially in low w/c ratio lightweight concrete. As the lightweight concrete sets durin g the initial hydration and as localized areas become deficient of water, the

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28 absorbed wat er in the large pores of the lightweight aggregates act a s repla ce ment of the mixing water and/or it hydrate s the dry cement particles. The absorbed water is drawn by gravity or capillary force from its por es therefore extending the curing period internally (Figure 2 5 ) This process promotes the early age strength of the concrete which is crucial for tilt up construction It also eliminates / minimizes shrinkage crac king and reduces the permeability of the concrete. This process of hydrating the cement internally carries on at later ages as well. ( ACI.213 2003 ) Modulus of Elasticity The modulus of each concrete component such as mortar and aggregates, affect the overall modulus of elasticity of the concrete. Normal concrete has a hig her modulus of elasticity than the lightweight concrete due to the higher modulus of the natural coarse aggregates ( Lamond 2006 ) to that of the same strength normal concrete ( Figure 2 6 and Figure 2 7 ) which means that the lightweight concrete is more flexible. ACI 318 201 1 Building Code Requirements for Structural Concrete, permit the use of the formula below to obtain the modulus of elasticity for any concrete with density between 90 and 160 lbs. / ft 3 and compressive strength between 3000 and 5000 psi or to be taken as 5 7,000 However, the actual value of the modulus of elasticity may vary by up to 20%. ( ACI.213 2003 ) (2 1)

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29 Nevertheless, in other section of the ACI 318 2011 multiplied by for the sand lightweight concrete. This factor accounts for the lower tensile stre ngth of the lightweight concrete. ( ACI.318 2011 ) Modulus of Rupture The tensile strength is a function of the tensile strength of the coarse aggregate and mortar, and the bond between them. The tensile strength is traditionally defined as a function of the compressive strength, but this is an approximation and does not reflect the surface condition the moisture of content, distribution and most importantly the aggregate strength ( Lamond 2006 ) The ACI committee 213 states that tensile strength of the lightweight concrete may not increase in a manner comparable with the compressive strength increase especially in high strength lightweight concrete. Figure 2 8, shows that lighter density concrete have a wider range of modulus of rupture than of the normal density concrete. The equation below describes the modulus of rupture (f r ) as a function of the compressive strength of concrete ( c concrete reduction factor. ( ACI.318 2011 ) (2 2) Tilt up and Lightweight Structural Concrete No literature has been found to shed a light on the effect s of the lightweight concrete on the tilt up wall system. One important factor that influences the tilt up wall system is self weight. This is due to the significant contribution that self weight has in the P ( Figure 2 9 ) ACI 551 2010, considers the self weight of the additional concentrated axial load acting downwa rds at mid height (Figure 2 10)

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30 The Tilt up Construction Product Handbook, by Dayton Superior, suggests a reduction factor of 0.85 for the lightweight concrete when calculating the allowable tensile stress. Another reduction factor of 0.70 is suggested w hen calculating for the lifting inserts. ( Superior 2009 ) Maturity The strength of concrete is a result of exothermic chemical reactions between the cement and the water in the mixture. The ( hydration ) reaction is a function of temperature, the higher the temperature of the concrete, the higher the reaction rate In addition, the hydration reaction itself generates heat l eading to a faster gaining of strength in the concrete. ( ACI.228 2003 ) The maturity is a method of tracking t he temperature and time of the concrete to estimate the strength of the in place concrete. The thermal history of the concrete is used through mathematical equations to calculate the maturity index. As mentioned earlier, the rate of hydration depends on th e amount of cementitious materials and water. Thus, each concrete design mixture has a unique maturity index. ( Carino 2008 ) In 1940, the maturity method was developed by McIntosh Nurse and Saul. The function was developed to account for the temperature history. Nevertheless, in 1977 another function (equivalent age) was developed based on Arrhenius equation that considers the temperature effect of the reaction rate. It measures the maturity index of a certain time and compares it to and equivalent age at a reference temperature, normally 20C. Nowadays, Maturity method of estimating the strength of concrete is widely used in concrete pavement const ruction to decide on the appropriate time to open road pavement to traffic. It is also used for form stripping, removal of Shoring and re shoring,

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31 post tensioning, loading structures, saw cutting and harvesting pre cast members. Hence, maturity method can equally well be applied to estimate the strength of the concrete before lifting a tilt up panel. Nurse Saul Maturity Method Nurse Saul maturity method, currently known as Temperature Time Factor, was based on empirical observations. It was devel oped under the assumption that for certain mixture of concrete two samples with the same maturity would have the same strength regardless of curing conditions ( Figure 2 11 ) Calculation of the Temperature Time Factor requires the calculatio n of the d atum temperature It is the lowest temperature at which the hydration reaction occurs. In hot weather areas, the datum temperature can be assumed to equal 0 C unless a high accuracy estimate of the concrete strength is required. I n such a case, ASTM C 1074 2011 procedure for calcul ating the datum temperature is preferable. Figure 2 12 illustrates that the temperature time factor (maturity index) is calculated by recording the area between the temperature curve and the datum temperature. ( AS TM C1074 2011 ) Equivalent Age The temperature required to produce a maturity equal to the maturity achieved by a curing ( ASTM C1074 2011 ) The equivalent age exponenti al function follows the rules of the Arrhenius equation that describes the rate of the reaction based o n the thermal properties It converts the actual age of the concrete to an equivalent age at a specified temperature The calculation of the Equivalent A ge requires the value of activation energy or the energy

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32 needed for the molecule to generate a reaction. It depends on t he cement type, admixture and water/cement ratio. Generally, for type I cement without admixtures, the value of the activation energy is between 40,000 45,000 J/mol. ( ASTM C 1074 2011 ) It has been investigated that the equivalent age maturity method is more accurate in describing the effect of temperature on concrete strength over a wider range of temperatures than the temperature time factor method. It overcomes the linear approximation of the Nurse Saul equation. Figure 2 1 3 further illustrates the effect of different activation energy values at different temperatures. It also shows that for a low activation energy concrete, the temperature time fa ctor is an accurate method of estimating the strength of concrete. However, for higher activation energy and wider sprea d of temperature range, the equivalent age method is superior. Despite these facts, both functions fail to account for the effects of ea rly age temperature. ( Carino 2008 ) COMA Meter The COMA meter is a disposable glass capillary tube containing a liquid for which the rate of evapora tion varies according to the Arrhenius equation. The tube has a scale from 0 to 14 days which reflects the maturity of the concrete according to the equivalent age factor with a reference temperature of 20 C and activation energy of 40 KJ/mol. The value of the activation energy of the COMA meter (40 KJ/mol) was determined based on various studies. The studies concluded that the activation energy is proportional to temperature and that for concrete temperat ure between 5 43 C, the average activation energy is 37 39 KJ/mol. ( Hansen 1982 ) The capillary tube is to be activated by breaking the tube at 0 days and then pressed into the fresh concrete in a container. The maturity i s measured by removing

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33 the capillary tube from its container and reading the level o f the liquid against the scale (Figure 2 14) The tube can be placed back into the container for further monitoring if the required maturity is not achieved. Pullout The pullout test originated in the Soviet Union around 1938, but the test mainly measures the tensile strength of the concrete based on the factures mechanism and not the compressive strength In1962, Danish Lok meaning punch out was developed to estimate the in situ strength of concrete It measures the power required to pull out a metal di sk embedded in the fresh con crete The measured force can then be used to estimate the compressive and tensile strength of the concrete. It is considered a semi destructive test due to the damage incurred by pullout testing, however good patching of th e te sted concrete is achievable The test that is most commonly used in industry today is the pullout test as The metal disk is pulled using a jack reacting with a bearing ring pushing against the concrete ( Figure 2 15 and Fi gure 2 16 ) The pullout strength is measured by the maximum force require to fracture the concrete by pulling on the metal insert or by loading the disk to the required threshold The force exerted provides an approximation of the concrete's compressive, t ensile and shear strengths. ( Stone, Carino et al. 1986 ) Commercial metal inserts are available with depths ranging from 1 to 1.2 in. Thus, only the surface of the concrete is tested. Therefore 7 to 10 % variation within the same patch is expected ( ACI.228 2003 ) Consistent empirical correlations can be established between strength properties and pullout test methods. Lig htweight concrete utilize different empirical correlations than the normal weight concrete due to the lightweight

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34 aggregates used and the fracture patterns It has been shown that for lightweight concrete aggregates the pullout test yields significantly lo wer coefficient of variation (6%) than the harder aggregate concrete. In general, p ullout test results have been estimated to be within 8% accuracy for laboratory and field testing conditions when the test procedure has been performed properly and a prope r correlation has been developed. ( Stone, Carino et al. 1986 ) Literatures tend to disagree on the failure mechanism of the pullout test. Some claim the failure in the concrete is directly related to the compressive strength of the concrete. Other s literature conclu ded that failure is due to the fracture toughness of the matrix or mortar strength. However, all studies indicate the existence of a correlation between the pullout force and the compressive strength of the tested concrete. ( ASTM C900 2006 ) Strain s and Stresses in Tilt up Panels Strain gauges ar e used t o detect and monitor the change in length of an element subjected to loads. Some gauges are static, reading strain s in a slow manner such as th e ones embedded in the concrete. Contrarily, dynamic gauges can monitor strains in a fraction of a second. The el ectrical resistance gauges are among the most common strain measuring devices. They are made of a flat grid of wires and generally mounted using an epoxy bond to the surface of the material being tested. They operate by detecting the changes of the resista nce in the electrical field due to the compression or stretching of the gauges. They are id eal for dynamic loading and monitoring of any material, in our case concrete.

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35 The surface of the tested material must be clean and free of dirt to allow a proper adh esion of the gauges. In the case of concrete, long gauges are used to overcome the effect of the local variations of the concrete mix ture The gauge length should be at least four times the size of the coarse aggregates. ( IAEA 2002 ) In a study conducted by AbiNader, a tilt up panel was instrumented with surface mount electrical strain gauges at the locations of the maxi mum calculated bending stresses. The strains were monitored during the tilting of the panel from 0 to 90 degrees. The results were compared with different finite element software. It was concluded that the maximum stresses were exerted at 0 degree angle wh ere a suction force exists between the tilt up panel and the casting bed In this research, a similar technique was used to monitor the strain in the lightweight concrete tilt up panel during lifting

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36 Figure 2 1. Tipping table use in tilt up construc tion ( TCA 2011 ) Figure 2 2.

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37 Figure 2 3. Sc ( Greatbuildings.com 2012 ) Figure 2 4 Fire rating for various densities of concrete ( ACI.213 2003 )

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38 Figure 2 5. Normal vs. lightweight concrete curing characteristics ( Norlit e 2012) Figure 2 6 Modulus of elasticity of different densities of concrete ( ACI.213 2003 )

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39 Figure 2 7 Normal vs. lightweight concrete modulus of elasticity ( Nawy and Nassif 2008 ) Figure 2 8 Modulus of rupture for different densities of concrete ( ACI.213 2003 )

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40 Figure 2 9 Wall design model (Source: ACI 551.2R10) Figure 2 10 Panel self weigh (Source: ACI 551.2R10)

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41 Figure 2 11 Temperature Time Factor ( Nixon, Schindler et al. 2008 ) Figure 2 12 Thermal his tory curve ( Carino 2008 )

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42 Figure 2 1 3 Age conversion factor according to activation energy ( Carino 2008 ) Figure 2 14. COMA maturity meter (photo courtesy of Adel Alsaffar)

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43 Figure 2 1 5 Cross section of pullo ut test (ASTM C 900 06 ) Figure 2 16 P rinciple of pullout test ( Harrison 2003 )

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44 CHAPTER 3 R ESEARCH METHODOLOGY General Introduction This section deals with the lightweight concrete mix design specifications a nd admixtures It also discusses the various physical testing performed on fresh and hardened concrete. In addition, it covers the nondestructive testing procedures performed to estimate the strength of the concrete. Three different maturity concepts were test ed using temperature time factor, equivalent age and the COMA meter The pullout strength test, a semi destructive test, was also conducted to evaluate the strength of the lightweight concrete Finally, strain gauges instrumen tation procedure s are highlighted. The research called for two b atches of the same lightweight concrete mixture. The first b atch is a control b atch which was utilized to cast concrete specimens that were tested to establish the maturity strength and pull out strength relationships The second b atch is an experimental b atch, which was used to cast the tilt up wall and concrete test specimens. Concrete Mix ture Design Concrete is normally characterized by its 28 day compressive strength such as 4,000 or 5,0 00 psi concrete. Although the compressive strength is important for any tilt up construction project, the early age strength of the concrete is vital. The tilt up wall must gain sufficient strengt h at early age to facilitate lifting after a few days from c ast ing. ACI committee 551 requires a 28 day minimum compressive strength of 3,000 psi Nevertheless, the lifting insert manufacturers call for a compressive strength of 2,500 psi at the day of lift. Therefore, higher 28 day strength is commonly specified t o lift the

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45 panels as fast as possible. Another factor a ffecting the lifting of the panels is the flexural strength of the concrete ; 28 day modulus of rupture of 550 psi is recommended to avoid flexural cracking Lifting inserts manufacturers ask for modulu s of rupture of 400 to 500 psi if the bending stresses are below 250 psi. Consequently, a concrete mixture is sometime proportioned for early compressive and flexural strength gain For example, cementitious materials such as fly ash and slag slow the rate of early strength gain and can disturb panel finishing. Also, air entraining agents reduce the strength of the concrete leading to cracking particularly during the lifting operation. ( ACI.551 2010 ) Structural lightweight concrete number H65BC from Florida Rock Industries in Gainesville was found suitable for this rese arch. Table 3 1 describes the mix design of the lightweight concrete used in this project The studied structural lightweight concrete, H65BC, is composed of natural sand and lightweight coarse aggregates. Detailed contents of the concrete are stated below. Cement T.S. Baker Cement Plant supplied the cement used by Florida Rock Industries to produce the lightweight concrete. Table 3 2 lists the chemical and physical properties of the cement. Air Entrained Agent The air entraining agent, AEA 92S, manufactured by Euclid Concrete Admixtures was used in the tested concrete It meets or exceeded the requirements of ASTM C 260 AASHTO M 154 ANSI/NSF STD 61 and Corps of Engineers CRD C 13

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46 Water Reducer The wate r reducing admixture, EUCON WR, manufactured by Euclid Concrete Admixtures was added to the concrete It meets the requirements of ASTM C494 (Type A and D), AASHTO M194 and ANSI/NSF STD 61. Coarse Aggregates produced by the rotary kiln method conforming to ASTM C 330 was used in the concrete mix ture The lightweight coarse aggrega te was manufactured by STALITE. The properties of the aggregate used in the lightweight concrete are stated in Table 3 3 Fine Aggreg ate The physical properties and sieve analysis of fine aggregates used in the lightweight concrete provided by Florida Rock Industries are listed in Table 3 4 Preparation of Concrete Specimen s Ready mix structural lightweight concrete was used to prepare thirty x 12 ) cylinders and fifteen x 2 ) beams for the control b atch. The experimental b atch x 12 ) cylinders and eight x 2 ) beams. Table 3 5 and Table 3 6 l i st the sample s acquire d from each b a t ch. The control batch specimens were prepared according to ASTM C 31, Standard Practice for Making and Curing Concrete Test Specimens in the Field with a sample concrete acquired according to ASTM C 172 20 10 Standard Practice for Sampling Freshly Mixed Concrete The specimens were prepared in molds and cover ed with plastic to avoid drying. A day later, the se specimens were submerged under water until testing as per ASTM C 511 2010 Standard Specification fo r Mixing Room s, Moist

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47 Cabinets, Moist Rooms, and Water Storage Tanks Used in the Testing of Hydraulic Cements and Concretes ( Figure 3 1 ) For the purpose of this research, the specimens of the experimental batch were made accordin g to ASTM C 31, but cured in their molds under the same condition as the tilt up wall. The concrete sample w as acquired according to ASTM C 172 2010 Concrete Cylinders All specimen s were prepared according to ASTM C 192 in 6 cylinder molds The molds were pre waxed for easier unmolding process and to prevent concrete for sticking to the surface The concrete was added in a mold using a metal scoop in a circular motion around the perimeter of the mold in 3 equal layers. Each layer was consol idated by rodding the concrete 25 times and hand tapping the side of the mold 10 15 times ( Figure 3 2 ) The access concrete was stroked off the top and finished using a trowel before it was covered with plastic. Two temperature l oggers were embedded midway in two of the concrete cylinders. The loggers were inserted in a hole made by tamping rod before tapping the molds to close the void. The loggers were immediately activated to record temperature and time For the control batch, s ome of the cylinder molds had a pullout test insert fixed to the bottom; they were tested to ensure a water seal. Other concrete specimens received the pullout test insert in a floating cup after finishing ( Fig ure 3 3 ) The inser ts in this case were pressed and vibrated into the concrete to guarantee proper concrete encasement. ( ASTM C192 2007 ) For the experimental patch, 15 cylinders were prepared using the same method. In two of the cylinder specimens a COMA meter were pressed into the concre te to

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48 measure the maturity of the concrete and compare it with the maturity of the tilt up wall ( Figure 3 4 ) Concrete Beams All specimens were prepared according to ASTM C 192 in hard plastic beam molds. The molds w ere sprayed with oil to facilitate for easier unmolding process and prevent concrete for sticking to the wall s of the mold s The concrete was added in the molds using a metal scoop in 2 equal layers. Each layer was consolidated by rodding the concrete 63 t imes and tapping the molds with a rubber mallet 10 15 times. The access concrete was stroked off the top and finished using a trowel before it was covered with plastic. ( ASTM C192 2007 ) Two temperature loggers were embedded midway in two of the concrete beams. The logger s were inserted in a hole made by tamping rod before tapping the molds to close the void. The loggers were immediately activated to record temperature and time ( Figure 3 5 ) Tests on Fresh Concrete Multiple tests w ere performed according to ASTM standards to ensure the quality of the delivered concrete. Concrete sample was collected in accordance with ASTM C 172 2010 Standard Practice for Sampling Freshly Mixed Concrete Slump of Hydraulic Cement Concrete The s lum p test A clean plastic mold was dampened and placed on a flat non absorbent base plate see Figure 3 6 Then a sample of the freshly mixed concrete is collected from the Ready Mix concrete. The mold was firmly held in position by stepping on the foot pieces of the mold. The first layer of concrete was then placed in the mold (approximately 1/3 by volume) and

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49 compacted by striking it measuring 5/8 in diameter. A second layer of concrete was added to the 2/3 of the mold by volume, and compacted by a rod strokes just enough to penetrate the first layer. A third layer of concrete was added to the full height of the cone mold and compacted in the same mann er as in layer two. The excess concrete was stroked off flush with the top of the mold by the tamping rod. The area around the mold was cleaned before the mold was slowly lifted upward. The vertical difference between the mold and the center of the concret e top surfa ce was immediately measured ( Figure 3 7 ); all in accordance to ASTM C 143 2005 The slump results for the control and experimental batch were measured at Air Content of Freshly Mixed Concrete by Volumetric Method Air entraining agent s are added to the concrete mixture to incorporate air bubbles which improve the concrete against scaling due to freezing and thawing cycles. A common and less complicated method to measure the air content in the concr ete is the pressure method pr ocedure explained in ASTM C 231. However, this method is applicable to dense aggregate concrete only On the other hand, ASTM C 173 2001, the volumetric method, is the only acceptable air content measure in lightweight aggrega te concrete because it measures the air in the mortar and not the voids in the aggregates. The air meter ( Figure 3 8 ) consist s of two sections a bowl and a top cover. The needed tools are listed below: Funnel to add water without disturbing the concrete. Tamping rod 5/8 in. diameter and at least 12 in. long. Strike off bar. Calibrated cup. Measuring Vessel for Isopropyl Alcohol Isopropyl Alcohol

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50 Mallet rubber, weighing 1.25 0.5 lb The bowl was damped and fil led with freshly mixed concrete in two layers. Each layer was stroked 25 times for compaction and taped with the mallet 10 15 times to close the voids cause by rodding. Water and alcohol w ere added using the funnel after fixing the top section of the air meter. Approximately 2 p in t s of alcohol was used to reduce the amount of foam ( Figure 3 9 ) The meter was inverted and sho o k for 5 seconds at a time for a minute, and then it was rolled at a 45 degree angle for another minute. The initial reading was recorded to the nearest 0.25% after the cap was removed and the pressure stabilized. The f inal air content reading was recorded after a nother minute of rolling and pressure stabilization The measurement of air from control and experi mental batched are recorded in Table 3 7 Unit Weight The plastic unit weight of the lightweight concrete was determined by weighing the concrete using a bowl with a known volume and weight. The plastic unit weight of the lightweight concrete was later calculated by dividing the weight of the concrete by the volume of the bowl. The plastic unit weights were calculated to be 115 lb /cf and 117 lb/cf for the control and experimental batch respectively. Temperature Test The temperature of the lightweight concrete was recorded in accordance to ASTM C 1064 by pressing an approved thermometer in the fresh concrete until the temperature stabilized ( Figure 3 10 ) The r eading was recorded to the neare st 0.5 F. The temperature of the control batch of concrete was recorded at 78 F when the ambient temperature was 70.5 F. The Experimental batch of concrete registered a temperature of 8 2 F when the ambient temperature was 7 9 F.

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51 Tests on Hardened Concre te Multiple tests were performed according to ASTM standards to ensure the quality of the delivered concrete. The c oncrete sample was collected in accordance with ASTM C 172 2010 Compression Test C ompression test s were performed for the control batch cyli ndrical specimens at 1, 4 7, 14 and 28 days as per ASTM C 39 The specimens were capped according to ASTM C 617, Standard Practice for Capping Cylindrical Concrete Specimens ( Figure 3 11 ) A FORNEY FX250/300 compression testing machine was used to apply a load rate of 35 psi/sec (1000 lb/sec) until failure In a similar procedure, the experimental batch cylinders were tested at 1, 3, 7 and 10 days The compressive strength of the cylinders was obtained by dividing the maximum applied load by ave rage cross sectional area as follows: (3 1) Where, S = Compressive strength (psi), P = Maximum load (lbs.), this case. Two c ylindrical specimens were tested for compressive strength at each testing day. The average compressive strength s w ere compar ed with the range of strengths making sure they are within 1 0 % of the average as required by ASTM C 1074.

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52 Third Point Flexure Test Third Point Flexure tests were conducte d for the control batch at 1, 3, 7, 14 and 28 days according to ASTM C 78 ( Figure 3 1 2 ) The axial loads were applied at an approximate rate of 2700 lb/min. E xperimental batc h beams were also tested at 1, 3, 7 and 10 days The following equation was used to calculate the modulus of rupture: (3 2) Where: R = M odulus of rupture (psi) P = M aximum applied load (lb) L = S pan length, ( in. ) b = A verage width of specimen ( in. ) at the fracture, and d = A verage depth of specimen, ( in. ) at the fracture. Two beam speci mens were tested for flexural strength at each testing day. The average flexural strengths were compared to make sure they are within 15 % of the average as required by ASTM C 1074. Maturity Method Estimation of early age strength of concrete is important i n many concrete applications such as stripping forms, re shoring and opening concrete pavement to traffic. It is particularly critical in the tilt up construction since the construction process can depend on the concrete reaching sufficient strength prior to lifting the walls Therefore, different maturity methods were utilized to estimate the strength of the concrete prior to lifting; since they are reliable, easy to perform and non destructive.

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53 Maturity Method Process Fifteen fif teen the lightweight concrete (control batch). Temperature loggers were inserted at mid depth of two cylinders and two beams. The loggers were activated as soon as they were inserted to record the temperature of the concrete. Mechanical testing of compressive and flexural strengths were performed on two specimens at day 1, 3, 7, 14 and 28. Depending on the maturity method tested, maturity index is calculated using different methods A strength maturity relationship wa s then plotted showing the average strength of concrete at different maturity stages. A best fit curve was drawn using a log function in Microsoft Excel. These relationships w ere used to estimate the real time strength of the tilt up wall. In addition, the relationship s were also verified in the experimental batch by testing cylinders and beams for strength. Evaluating the Strength of Concrete Using Temperature Time Factor Temperature Time Factor (TTF) was one of the method s use d in this research to estimat e the strength of the lightweight concrete. The control batch temperature history (temperature loggers) and strength (specimens testing) were recorded to compute the temperature time factor as follows: (3 3) Where: M (t) = temperature time factor ( maturity index ) at age (t), degree hour, T a = average concre te temperature T o = datum tem perature (usually taken to be 0 C), and s ).

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54 TTF was use d to establish the strength maturity curve that references the strength of the concrete mix as a function of its maturity. E valuating the Strength of Concrete Using the Equivalent Age Method The equivalent age method was also applied to predict the strengt h of the lightweight concrete in the tilt up panel. Temperature loggers were used to record the temperature history and specimens were tested for strength to produce the equivalent age based relationship by applying the following equation: (3 4) Where: t e = equivalent age at a specified temperature T s days or hours; E = Activation energy obtained experimentally, kJ/mol ; R = Molar gas constant = 8.31 J/ mol.K; T a = average temperature of concrete during in terval t, K; T s = specified temperature, K; and t = time interval, days or hours. The activation energy was assumed to be equal to 40,000 J/mol based on literature recommendations for type I cement ( ASTM C1074 2011 ) C alculations were performed; they concluded that different activation en ergy value s had minimal effect on estimating the strength of the tested lightweight concrete under the research curing conditions (Figure 2 13) Maturity Measurement Device IntelliRock TPL temperature loggers manufactured by ENGIUS were used to record the thermal history of the lightweight concrete The loggers conform to the ASTM

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55 C 107 requirements for digital loggers. Table 3 8 shows the specifications of the temperature loggers. IntelliRock II reader was used to read the logge rs and transfer the data to computers via software; Table 3 9 temperature data were used to calculate the Maturity Index. In the control batch, t wo loggers were embedded in the concrete cylin ders and another two were inserted in the beam specimens. Same loggers were embedded in the tilt up panel and cylinder specimens from the experimental batch. Pullout Strength Method The pullout test (LOK test) used in this experiment is manufactured by Ge rmann Instruments. It comprises of 25 mm steel discs at a 25 mm depth ( Figure 3 13) A hydraulic, hand operated, pull machine records the maximum force required to cause fracture of the concrete The fracture caused by the pull fo rce has generally shape of a cone ( Figure 3 14 ). Fifteen cylinders were prepared using the control batch to establish strength pullout relationship. Ten cylinders had the inserts fixed to the bottom for the molds, 2 with the inser ts placed on top with a floating cup and the rest had inserts at both ends ( Figure 3 15 ) Two inserts were tested at day 1, 3, 7, 14 and 28 The discs (inserts) were pulled using a hydraulic pull machine with a digital gauge. The machine recorded the maximum force required to pull the inserts. The average maximum forces were plotted with the corresponding strengths to establish a reference strength pull relationship. This relationship was used to estimate the strength of the concre te in the tilt up panel.

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56 The tilt up pa nel was also instrumented with discs fixed on the formwork along the panel sides as shown in Figure 3 16 A disc was also inserted in the surface of the concrete panel at an ang le to ensure full encasement The comple te process of the pullout strength test is shown in Figure 3 17 for a floating cup disc inserted in the surface of the tilt up panel concrete. The panel inserts were taken as a measure of the concrete strength after they were comp ared to the pullout strength relationship curve created with the control batch Strain Measurements N2A 06 40CBY 350/P surface mount strain gauges manufactured by Micro Measurements a branch of Vishay Precision Group were used in this project. The gauges is more than 5 times the size of the large aggregate Strain G auge Installation The strain gauge installation procedure was done in two major steps using M Bond AE 10 kit su pplied by Micro Measurements Surface p reparations The surface of the concrete was first cleaned with a stiff bristle brush to remove any dust particles ( Figure 3 1 8 A) Then, isopropyl alcohol was applied to the gauge location a fter it was marked to clean any contaminants ( Figure 3 18 B) Although the concrete surface of the panel received a smooth finish, there were some voids and air pockets that might affect the gauge bonding and reading. Therefore, t he M Bond was used as a sealer to the surface of the concrete ( Figure 3 18 D) The adhesive was then applied to the surface of the concrete filling out any voids after it was mixed with the curing agent 10 for five minutes and was let to stand for another five minutes ( Figure 3

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57 18 C) The M Bond was left to cure overnight before it was abraded using sandpapers starting with 80 grit and ending with 360 grit The purpose of the abrading was to expose t he con crete area with voids being filled with the M Bond as well as creating a smooth area to bond the gauge. Gauge b onding The surface of the concrete was cleaned with isopro pyl alcohol. The gauge was placed in its final position and orientation using a piece o f tape ( Figure 3 1 9 A) The gaug e was then lifted and a light coa t of adhesive was applied to the bonding surface of the gauge and the surface of the concrete ( Figure 3 19 B, C and D ). The gauge was align ed and remounted to the concrete with hand pressure applied to ensure proper distribution of the bond ( Figure 3 19 E and F ). Silicone rubber was placed on top of the gauge for protection before a 10 psi of dead weight was applied to each strain gauge and left to cure overnight ( Figure 3 19 G an d H ). Due to limited resources, 3 strain gauges were installed at a time. Data Acquisition System Two compatible data acquisition conditioners (DA), D4 by Micro Meas urements, were used to monitor the strain gauges as the tilt up wall was being lifted. Each was connected to 4 quarter bridge gauges, taking 8 readings per second. The DAs are portable and operate on USB power. The DAs were connected to a computer via soft ware ( Figure 3 20) Table 3 10, summarizes the D4 specifications.

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58 Table 3 1 Mix Design for structural lightweight concrete (H65BC) Material ASTM TYPE Quantity Cement C 150 II 650 Lbs Water -250 Lbs Fine Aggregate C 33 Sand 1130 Lbs Aggregate C 330 #7LTWT 1075 Lbs Air Entrained C 260 AEA 92S 3.0 oz. Water Reducer C494 EUCON WR 55 oz. W/C Ratio 0.39 Slump (in) 5 1" Air Content (%) 4.5 1.5% Plastic Unit Wei ght (lbs/cf) 115.1 1.5 Materials per Cubic Yard

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59 Table 3 2 Chemical and physical properties of type I & type II cement LIMIT ASTM C150 FL. DOT 921 & AASHTO M 85 COMPOSITION Chemical Compounds Silicon Dioxide (SiO 2 ) 19.6 Aluminum Oxide (Al 2 O 3 ) Maximum 6% 6% 5.2 Iron Oxide (Fe 2 O 3 ) Maximum 6% 6% 3.6 Calcium Oxide (CaO) 63.6 Magnesium Oxide (MgO) Maximum 6% 6% 0.9 Sulfur Trioxide (SO 3 ) Maximum 3% 3% 3.1 Loss of Ignition (LOI) Maximum 3% 3% 2.7 Insoluble R esidue (IR) Maximum 0.75% 0.75% 0.29 Sodium Oxide (Na 2 O) 0.09 Potassium Oxide (K 2 O) 0.33 Alkalies (Na 2 O equivalent) Maximum 0.60% 0.60% 0.31 Tricalcium Silicate (C 3 S) 61.2 Dicalcium Silicate (C 2 S) 10.1 Tricalcium Aluminate (C 3 A) % Maximum 8% 8% 7.6 Tetracalcium Aluminoferrite (C 4 AF) 11.0 CaCO3 in limestone, % Minimum 70% 70% 98% Limestone, % Maximum 5% 5% 3.7% Physical Test Results (ASTM C204) Blaine Fineness, m2/kg Minimum 280 280 393 (ASTM C191) Vicat Set, minutes Initi al Set Minimum 45 45 112 Final Set Maximum 375 375 212 (ASTM C185) Air Content % Maximum 12% 12% 6.3% (ASTM C 151) Autoclave Expansion Maximum 0.80% 0.80% 0.0 (ASTM C186) 7 day heat of hydration cal/g Maximum N/A 80 78 C 3 S = 4.75* (C 3 A) Maximum 100 10 0 97

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60 Table 3 2. Continued LIMIT ASTM C150 FL. DOT 921 & AASHTO M 85 COMPOSITION Physical Test Results (Continued) Compressive Strength, psi 1 day 2340 3 days Minimum 1740 1740 4100 7 days Minimum 2760 2760 5220 28 days 7200

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61 Table 3 3 Properties of Lightweight Coarse Aggregate Content Absorption : Saturated Surface Dry (ASTM C 127) 6% 1 Hour Boil In Water 8% Under high pumping pressure of 150 psi 9.4% Soundness (% Loss) Maximum Magnesium Sulfate ( ASTM C 88)) 0 0.01% Sodium Sulfate (ASTM C 88) 0 0.23% 25 Cycles Freezing and Thawing (AASHTO T 103) 0.22 0.80% Toughness : Los Angeles Abrasion (AASHTO T 96) 25 28% Stability : Angle of Internal Friction (Loose) 40 42 Angle of Inter nal Friction (Compacted) 43 46 Typical Density (Unit Weight) : Dry Loose (ASTM C 29) 52 lbs/cf Dry Rodded (ASTM C 29) 58 lbs/cf Saturated Surface Dry Loose (ASTM C 29) 53 lbs/cf Maximum Dry Density (ASTM D 4253) Damp Loose (ASTM C 29) 50 54 lb s/cf Typical Relative Density (Specific Gravity) : Dry (ASTM C 127) 1.54 Saturated Surface Dry (ASTM C 127) 1.60 Range in Saturated Surface Dry (ASTM C 127) 1.57 1.64 Sieve Size : % Passing 100 100 100 90 100 #4 40 80 #8 0 20 #16 0 10

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62 Table 3 4 Properties of the Florida Rock Industries fine a ggregate Physical Properties : Fineness Modulus 2.25 Dry Unit Weight 95 lb/cft Absorption 0.5 % Sieve Size : % Passing #4 99.7 #8 98 #16 86 #30 59.6 #50 25.9 #100 5.6 Table 3 5 Concrete specimen s, c ontrol b atch Test Specimen Size Number of samples Time of testing (days) Standard Compressive Cylinder 15 1,3,7,14 and 28 ASTM C39 Pullout Cylinder 15 1,3,7,14 and 28 ASTM C 900 Flexure Beam 15 1,3,7,14 and 28 ASTM C78 Table 3 6 Concrete specimens, e xperimental b atch Test Specimen Size Number of samples Time of testing (days) Standard Compressive Cylinder 15 1 3, 7 and 10 ASTM C39 Flexure Beam 8 1, 3,7 and 10 ASTM C78

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63 Figure 3 1 Concrete curing tank (photo courtesy of Adel Alsaffar) Figure 3 2. Rodding cylinder specimen (photo courtesy of Adel Alsaffar)

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64 Fig ure 3 3. Concrete cylinders with pullout inserts (photo courtesy of Adel Alsaffar) Figure 3 4. COMA meter pressed in concrete cylinders (photo courtesy of Adel Alsaffar)

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65 Figure 3 5 Temperature loggers in cylinders and beams (photo courtesy of Ad el Alsaffar) Figure 3 6 Slump test cone ( photo courtesy of Adel Alsaffar)

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66 Figure 3 7 Slump test scheme ( drawing courtesy of Adel Alsaffar) Figure 3 8 Air meter by volumetric method (ASTM C 173)

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67 Figure 3 9 Adding isopropyl alcohol to prevent foaming (photo courtesy of Adel Alsaffar) Table 3 7 Air content measurement Control batch Experimental batch First air content reading 5.25% 4.25% Second air content reading 5.50% 4.25% Approved air content 5.50% 4.25 %

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68 Figure 3 10 Measuring the temperature of concrete (photo courtesy of Adel Alsaffar) Figure 3 11 FORNEY compressive test machine (photo courtesy of Adel Alsaffar)

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69 Figure 3 12 upture Alsaffar) Table 3 8 IntelliRock temperature loggers s pecifications Operating Temperature 5 C to 85 C Storage Time & Temperature 0 to 35 C for 2 years. Max Temperature measurement Range 18 to 99 C (unwarranted outside of "operating temperature" range) Temperature Accuracy 1 C, 5 to 85 C Temperature Resolution 1 C Time accuracy 1 minute per month Temperature measurement rate 1 minute (resolution for min/max) Maturity integration period 1 minute Table 3 9 IntelliRock II Reader specifications Operating Temperature 5 C to 85 C Time accuracy 1 minute per month Logger data storage 999 logger downloads PC Interface USB

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70 Figure 3 13 Location of pull insert (disc) in the concrete (photo courtesy of Adel Alsaffar) Figure 3 14 Pullout fracture in a shape of a cone (photo courtesy of Adel Alsaffar)

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71 Figure 3 15 Cylinder pullout insert with floating cup (photo courtesy of Adel Alsaffar) Figure 3 16 Pullout insert attach (photo courtesy of Adel Alsaffar)

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72 A B C D E F Figure 3 17 Pullout process A) Pullout insert cup. B) Cup removed. C) Stem removal. D) Pull machine attachment. E) Pull machine. F) Surface of concrete after fai lure. ( p hoto courtesy of Adel Alsaffar)

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73 A B C D Figure 3 18 Surface preparation A) Clean with bristle brush. B) Wipe with isopropyl alcohol. C) Mixing M Bond adhesive. D) Apply adhesive. ( p hoto courtesy of Adel Alsaffar)

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74 A B C D E F G H Figure 3 19 Gauge bonding procedure A) Gauges and receiving surface. B) Gauge removal. C) Adhesive application to gauge. D) Adhesive application to surface. E) Installation and alignment. F) Adhesive distribution. G) Gauge protec tion. H) Applying pressure. ( p hoto courtesy of Adel Alsaffar)

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75 Figure 3 20 D4 data acquisition conditioner (photo courtesy of Adel Alsaffar) Table 3 10. D4 data acquisition conditioner specifications Strain Range 31,000 Resolution 1 Temperature 0 50 C Humidity 90% Relative Humidity

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76 CHAPTER 4 MATURITY METHODS Strength Maturity Relationship Three maturity techniques were used to estimate the strength of the lightweight concrete tilt up wall. Strength maturi ty relationships were established using the maturity equations. The strength maturity relationship defines the co mpressive strength as a function of the maturity index. In this research, strength maturity relationships were also created to reflect the rela tionship between flexural strength and maturity index. T emperature T ime Factor (TTF) As described in ASTM C 1074, the thermal history of the control patch of concrete was obtained using digital temperature loggers refer to A ppendix A for temperature logge r data. Consequently, t he temperature time factor ( maturity index or TTF ) was calculated according to Equation 3 3 The datum temperature was assumed to be equal to 0 C based on ASTM C 1074 2011 Compressive strength TTF relationship Table 4 1 lists the averages of temperature time factor and average compressive strength of the cylinders prepare using the control batch Pursuant to the obtained TTF and compressive strength s the data was plotted in Figure 4 1 The x axis indicates the maturity index or TTF in degree Celsius hours. The y axis is the compressive strength of the lightweight concrete. The data points were connected using the Trendline feature in Microsoft Excel. The best fit curve with the higher coefficient of determination (R 2 ) was the logarithmic curve The function of the relationship is shown in same figure.

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77 This curve/ function is unique to this particular lightweight design mixture. The function was used to estimate the compressive strength of the experimental batch at various maturity value s Flexural s trength TTF r elationship The TTF method was also applied using the control batch to establish a relationship between the maturity index and the flexural strength of lightweight concr ete mixture under study Table 4 2, shows the average of the modulus of rupture values at different maturity indices. The data were calculated using the third point flexural strength (psi) and th e temperature history ( C hrs). Figure 4 2 was plotted using the data point from Table 4 2 The Trendline feature in Microsoft Excel was used to sketch a best fit curve that follow a log arithmic function. The graph was later used to evaluate the flexural strength of the concrete during the experimental batch. It was also used to estimate the flexural strength on the tilt up panel before hoisting. Equivalent Age (EA) The equivalent age method was also used to estimate the compressive strength of the lightweight concrete. Although, it requires the calculation of the activation energy ASTM C 1074 2011 indicates that 40 45 KJ/mol is a good approximation. In this research, the activation energy was assumed to be 40 KJ/mol and reference temperature was taken at 20 C. These ass umptions coincide d with the COMA meter specifications Equation 3 4 was used to calculate the EA the concrete as per ASTM C 1074.

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78 Compressive s trength Equivalent Age r elationship Table 4 3 lists the averages of EA and compressiv e strength of control batch for each testing day. It can be noted that for the first 14 days the calculated Equivalent Age is higher than the actual age of the concrete This is due to the fact that the temperature of the concrete was higher than the refer ence temperature of 20 C. For example, the actual age of the concrete for the first 24 hours is equivalent to 28 hours of concrete maturing at 20 C. Beyond 14 days the temperature of the concrete dropped below the reference temperature leading to a less eq uivalent age compared with actual age. The values of the EA of the control batch were plotted against the corresponding compressive strength of the concrete, yielding an equivalent age compressive strength relationship ( Figure 4 3 ). This relationship was used to estimate the compressive strength of the lightweight concrete tilt up wall without performin g a compressive strength test. Flexural s trength E quivalent Age r elationship The equivalent age method was also applied to establi sh a flexural strength relationship. Table 4 4 displays the average flexural strength at different Equivalent age s One can notice that the same equivalent age versus actual age pattern was repeated for the beam specimens. The equ ivalent age started higher than the actual age until day 14. Figure 4 4 shows the relationship between the equivalent age in the x axis and the flexural strength in the y axis. The curve was used to predict the flexural strength of the lightweight concrete tilt up panel.

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79 Evaluation of Strength Maturity Relationship Establishing the strength maturity relationship was the first step to estimating the strength of the concrete given any maturity index. However and as an extra precautionary step, the relationsh ips were re verified by testing specimens taken from the experimental batch. Evaluating Temperature Time Factor Method In the experimental batch, two temperature loggers were inserted into the cylindrical concrete specimens to measure maturity in addition to two loggers in the panel. Concrete cylinders and beams were tested to verify the strength TTF relationship created in the control batch. Evaluating compressive strength TTF relationship Table 4 5 lists the experimental batch co mpressive strength test for cylinders cured next to the tilt up panel. It also lists the temperature time factor of the panel. Figure 4 5 shows the experimental relationship between compressiv e strength and the temperature time factor. It also shows an acceptable range of 10% according to ASTM C 1074 2011. The figure concludes that the relationship developed in the control batch yielded a good e valuation of the experimental batch compressive strength. Evaluating flexural strength TTF relationship Table 4 6 shows the flexural strength of the experimental batch beams and the temperature time factor. These values were used to verify the effectiveness of the developed control batch relationship. Figure 4 6 sh ow the flexural strength TTF curve of the control batch. It also plots the verification flexural strength with the corresponding T TF for the experimental batch. It also shows an acceptable range of 10% according to ASTM C 1074 2011. The figure

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80 indicates tha t the control batch relationship provided a very good prediction of the flexural strength of the panel. Evaluating Equivalent Age Method Using the equivalent age maturity method, the lightweight concrete strength of the panel was estimated using the develo ped control batch relationship. The relationship was also verified by testing cylinder and beam specimens at different age. Evaluating compressive strength EA relationship Table 4 7 shows the compressive strengths and their equiv alent age for the experimental batch. This data was used to verify the compressive strength EA relationship developed with the control batch. Figure 4 7 shows the verification data of the experimental batch with the control batch relationship d eveloped earlier. It also shows an acceptable range of 10% according to ASTM C 1074 2011. It is evident that the control batch compressive strength EA relationship yields an accurate approximation of the compressive strength of the experiment al batch. Evaluating flexural strength EA relationship Ta ble 4 8 shows the flexural strengths and their equivalent age for the experimental batch. This data was used to verify the flexural strength EA relationship developed with the control batch. Figure 4 8 shows the verification data of the experimental batch with the control batch relationship developed earlier. It also shows an acceptable range of 10% according to ASTM C 1074 2011. It is eviden t that the control batch flexural strength EA relationship yields an excellent approximation of the flexural strength of the experimental batch.

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81 Evaluating COMA Meter The COMA meter is a mini maturity meter that reflects the age of the concrete based on the equivalent age method. Four CO MA meters were used to test the maturity of concrete in the experimental batch. Two meters were placed in cylinder specimens, the others were inserted in the tilt up panel. Table 4 9 shows the average of COMA meter readings and co mpare s them to the equivalent age calculations It was noticed that the COMA meter readings were similar to the calculated equivalent age which means that COMA meter ultimately provided a good early age strength of concrete (within the first three days) However as the concrete further matured the COMA meter underestimated the strength of the concrete

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82 Table 4 1. Control batch TTF and compressive strength Cylinder Specimen s Time (Days) Time (hrs) Average (TTF) Temperature Time Factor (C hour) Averag e Compressive Strength (psi) 1 24 844 844 4 94 2,526 2,526 7 164 2,930 2,930 14 333 3,645 3,645 28 669 4,234 4,234 Numbers are rounded to the nearest integer

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83 Figure 4 1. Compressive Strength TTF Relationship y = 1064.8ln(x) 5730.8 R = 0.9907 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 0 2000 4000 6000 8000 10000 12000 14000 Compressive Strength (psi) TTF ( hr.) Control Batch

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84 Table 4 2. Control batch TTF and flexural strength Beam Specimen s Time (Days) Time (hrs) Average (TTF) Temperature Time Factor (C hour) Average Flexural Strength (psi) 1 25 598 220 3 71 1,518 406 7 165 3,293 542 14 333 6,376 646 28 669 12,493 713 Numbers are rounded to the near est integer

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85 Figure 4 2. Flexural Strength TTF Relationship y = 164.29ln(x) 809.36 R = 0.9867 0 100 200 300 400 500 600 700 800 0 2,000 4,000 6,000 8,000 10,000 12,000 14,000 Modulus of Rupture TTF (C hrs) Control Batch

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86 Table 4 3. Equivalent age and compressive strength Cylinder Specimen s Approx. Time (Days) Actual Time (hrs) Equivalent Age (hrs) Average Compressive Strength (psi) 1 24 28 844 4 94 101 2,5 26 7 164 173 2,930 14 333 337 3,645 28 669 658 4,234 Numbers are rounded to the nearest integer

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87 Figure 4 3. Compressive Strength Equivalent Age Relationship y = 1062ln(x) + 818.22 R = 0.9912 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 0.0 5.0 10.0 15.0 20.0 25.0 30.0 Compressive Strength, psi Control Batch

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88 Table 4 4 Equivalent age and flexural strength Beam Specimens Time (Days) Time (hrs) Equivalent Age (hrs) Average Flexural Strength (psi) 1 25 29 844 3 71 78 2,526 7 165 173 2,930 14 333 332 3,645 28 669 645 4,234 Numbers are rounded to the nearest integer

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89 Figure 4 4. Flexural Strength Equivalent Age Relationship y = 161.94ln(x) + 204.92 R = 0.9898 0 100 200 300 400 500 600 700 800 0.0 5.0 10.0 15.0 20.0 25.0 30.0 Modulus of Rupture, psi Control Batch

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90 Table 4 5 Com pressive strength TTF verification, experimental batch. Cylinder Specimen s Time (Days) Time (hrs) Average (TTF) Temperature Time Factor (C hour) Average Compressive Strength (psi) 1 25 787 1,670 3 76 2,178 2,620 7 168 4,350 3,389 10 249 6,430 3,989

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91 Figure 4 5. Verification of Compressive strength TTF relationship, experimental batch 0 1000 2000 3000 4000 5000 6000 0 2000 4000 6000 8000 10000 12000 14000 Compressive Strength (psi) TTF ( hr.) Experimental Batch 10 %

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92 Table 4 6 Flexural strength TTF verification, experimental batch Beam Specimen s Time (Days) Time (hrs) Average (TTF) Temperature Time Factor (C hour) Average F lexural Strength (psi) 1 25 787 1,670 3 76 2,178 2,620 7 168 4,350 3,389 10 249 6,430 3,989

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93 Figure 4 6. Verification of flexural strength TTF relationship, experimental batch 0 100 200 300 400 500 600 700 800 900 0 2,000 4,000 6,000 8,000 10,000 12,000 14,000 Modulus of Rupture, psi TTF (C hrs) Experimental Batch 10%

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94 Table 4 7 Compressive strength EA verification, experimental batch Cylinder Specimen s Time (Days) Time (hrs) Equivalent Age (hrs) Average Compressive Strength (psi) 1 25 46 844 3 76 128 2,526 7 168 255 2,930 10 249 367 3,645

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95 Figure 4 7. Verification of compressive strength EA relationship, experimental batch 0 1000 2000 3000 4000 5000 6000 0.0 5.0 10.0 15.0 20.0 25.0 30.0 Compressive Strength, psi Experimental Batch 10%

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96 Ta ble 4 8 Flexural strength EA verification, experimental batch. Beam Specimen s Time (Days) Time (hrs) Equivalent Age (hrs) Average Flexural Strength (psi) 1 25 46 284 3 76 128 447 7 168 255 590 10 249 367 650

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97 Figure 4 8. V erification of fle xural strength EA relationship, experimental batch 0 100 200 300 400 500 600 700 800 900 0.0 5.0 10.0 15.0 20.0 25.0 30.0 Modulus of Rupture, psi Equivalent Age at 20 C, days Experimental Batch 10%

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98 Table 4 9 COMA Meter and Equivalent Age Time of reading (hrs) COMA reading (days) COMA reading (hrs) Calculated EA Reading (hrs) 0 0 0 0 60 4.5 108 101 145 7.5 180 204 254 13 312 350

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99 CHAPTER 5 PUL LOUT METHOD Strength Pullout Relationship The p ullout strength test, as described by ASTM C 900, is a semi destructive test for estimating the compressive strength of the concrete. This test was performed on the control batch of the lightweight concrete to create a relationship between the pull force and the strength of the concrete. This relationship was then applied to estimate the strength of the tilt up panel before lifting. The pull force relationship with compressive strength and flexural strength wer e compared, results are stated below. It was observed at day 7 of the control batch that the pullout test has developed radial cracks in the cylinder specimen outside of the testing area ( Figure 5 1 A ). The cracks further develope d as the insert was being extracted out of the concrete ( Figure 5 1 B ). This may have been the reason for the off coarse reading in that day. T h is problem was resolved by e ncasing the cylinder specimen in a thick plastic pipe ( Figure 5 2 ). Compressive Strength Pullout Relationship Table 5 1 shows the pullout force obtained by applying the LOK test with the corresponding compressive strength The data was plotted with the pull for ce in the x axis and the compressive strength in the y axis. The points were connected via Microsoft Excel Trendline feature ( Figure 5 3 ). The best fit curve was applied as a linear function. The relationship was used to estimate the st rength of the tilt up wall.

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100 Flexural Strength Pullout Relationship The data for the pull force was used to develop a relationship with flexural strength of the lightweight concrete control batch Table 5 2 lists the values of th e pull force and the flexural strength of the lightweight concrete side by side. Figure 5 4 draws the relationship between the flexural strength and the pull force. This relationship was used to estimate the flexural strength of the tilt up panel. Evaluation of Strength Pullout R elationship The strength of the tilt up panel was estimated using the pullout test. Pullout inserts were embedded on the sides of the tilt up panel in addition to a surface insert. It was noticed that the pullout test performed on the side pullout underestimated the actual strength of the concrete; this was verified by testing the concrete specimens for strength. The estimating errors of the panel side inserts were related to the slenderness of the panel, 3.5 inches ( Figure 5 5 ) Nevertheless, t he surface insert yielded a good approximation of the strength of the panel with no visible cracks ( Figure 5 6 ). Evaluating Compressive Strength Pullout Relations hip Table 5 3 lists the pullout force of the experimental batch. It also lists two values surface. Figure 5 7 shows the compressive strength pullout curve for the control batch and the experimental batch data verifications. It also shows a 10% range of acceptable results. The acceptable range was derived from the acceptable variations of the pullout te st which may be as high as 36% of the average according to ASTM C 900 06. The acceptable range for this research was limited to 10% due to the critical nature of the tilt up operation.

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101 As previously discussed, most of the errors in the verification data ca n be attributed to the slenderness of the panel Generally, the inserts located in the tilt up panel sides underestimated the compressive strength of the lightweight concrete. In other words, the measured pullout force was less than the anticipated result according to the developed relationship in the control batch. However, the surface of the panel pul lout insert resulted in a compressive strength estimate that was in lin e with the control batch relationship Evaluating Flexural Strength Pullout Relations hip Table 5 4 indicates the values of the flexural strength of the lightweight concrete in the experimental batch and the corresponding pullout force. Figure 5 8 depicts the flexural strength pullout cu rve for the control batch and the experimental batch data It also shows a 10% range of acceptable results. The acceptable range was derived from the acceptable variations of the pullout test which may be as high as 36% of the average according to ASTM C 9 00 06. The acceptable range for this research was limited to 10% due to the critical nature of the tilt up operation. As previously stated the pull force results of the deviated more from the actual flexural strength of the ex perimental batch than their counterpart surface insert.

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102 A B Figure 5 1. Radial cracking on cylinder due to pull force. A) C racks at failure. B) Cracks at insert e xtraction. ( p hoto courtesy of Adel Alsaffar) Figure 5 2. Encased cylinder during p ullout testing (photo courtesy of Adel Alsaffar)

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103 Table 5 1. Pull force and compressive strength Cylinder Specimen s Time (Days) Time (hrs) Pullout Force (KN) Compressive Strength (psi) 1 24 6.3 1024 3 70 12.1 2059 7 161 17.65 2918 14 331 19.1 3627 28 667 21.6 4335

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104 Figure 5 3. Compressive strength pullout relationship y = 208.43x 406.74 R = 0.97 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 0 5 10 15 20 25 Compressive Strength, psi Pullout Strength, KN Control Batch

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105 Table 5 2. Pull force and flexural strength Cylinder Specimen s Time (Days) Time (hrs) Pullout strength (KN) Flexural Strength (psi) 1 24 6.3 246 3 70 12.1 399 7 161 17. 65 527 14 331 19.1 632 28 667 21.6 737

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106 Figure 5 4. Flexural strength pullout relationship y = 30.936x + 33.4 R = 0.97 0 100 200 300 400 500 600 700 800 0 5 10 15 20 25 Modulus of Rupture, psi Pullout Strength, KN Control Batch

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107 Figure 5 5. Cracking outside the testing area tilt up panel side (photo courtesy of Adel Alsaffar) Figure 5 6. Pullout insert, tilt up panel surface (photo courtesy of Adel Alsaffar)

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108 Table 5 3. Compressive strength and pullout, experimental batch Time (Days) Time (hrs) Pull Force (KN) Compressive Strength (psi) Pull Force (KN) Compressive Strength (psi) 1 25 10.1 16 70 3 76 12 2620 7 168 15 3389 10 249 17.2 3989 20.6 3989

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1 09 Figure 5 7. Verification of compressive strength pullout relationship 0 1000 2000 3000 4000 5000 6000 0 5 10 15 20 25 Compressive Strength, psi Pullout Strength, KN Experimental Batch, Tilt-up sides Experimental Batch, Tilt-up top 10%

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110 Table 5 4. Flexural strength and pullout, experimental batch Time (Days) Time (h rs) Pull Force (KN) Flexural Strength (psi) Pull Force (KN) Flexural Strength (psi) 1 25 10.1 284 3 76 12 447 7 168 15 590 10 249 17.2 650 20.6 650

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111 Figure 5 8. Verification of flexural strength pullout relationship 0 100 200 300 400 500 600 700 800 900 0 5 10 15 20 25 Modulus of Rupture, psi Pullout Strength, KN Experimental Batch, Tilt-up Sides Experimental Batch, Tilt-up Top 10 %

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112 CHAPTER 6 MATURITY AND P ULLOUT STRENGTH Pullout Strength Maturity Relationship ASTM C 1074 2011 states that for critical operations such as post tensioning or form removal, strength tests other than maturity should be performed for verification. The standard suggests tests such a s penetration resistant (ASTM C 803), cast in place mold (ASTM C 873) or pullout test (ASTM C 900). In this research, the pullout test was performed along with the maturity method to estimate the strength of the lightweight concrete before lifting the tilt up panel. As demonstrated in Chapter 5 the pullout strength is linearly proportionate to the compressive and flexural strength of concrete. Furthermore, it has been shown that compressive and flexural strength maturity relationship s exist Therefore, th e relationship between pullout strength and maturity was investigated to provide more confidence in the concrete strength estimation. Pullout Strength TTF The pullout strength test results were linked to the temperature time factor maturity method results. The links were used to estimate the compressive and flexural strength of the lightweight concrete. Table 6 1 lists the pull out force at different TTF values for the control batch. This data was used to establish a pullout strengt h TTF relationship. Pullout strength TTF compressive strength Figure 6 1 shows the relationship of the pullout strength and the temperature time factor maturity method. The relationship was developed using Microsoft Excel with the best fit curve being a logarithmic function. The secondary y axis shows the compressive

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113 strength of the concrete for easy reference. It was used as verification of the compressive st rength of t he t ilt up panel Pullout strength TTF flexural strength Figure 6 2 illustrate s the relationship of the pullout strength and the temperature time factor maturity method. The relationship was developed using Microsoft Excel with the best fit curve being a logarithmic function. The secondary y axis shows t he flexural strength of the concrete for easy reference. It was used as verification of the flexural strength of the tilt up panel. Pullout Strength Equivalent Age (EA) The pullout strength test results were linked to the equivalent age maturity method res ults. The links were used to estimate the compressive and flexural strength of the lightweight concrete. Table 6 2 lists the pullout strength at different equivalent ages for the control batch. This data was used to establish a pu llout strength EA relationship Pullout strength EA compressive strength Figure 6 3 shows the relationship of the pullout strength and Equivalent age maturity method. The relationship was developed using Microsoft Excel with the best fit curve being a logarithmic function. The secondary y axis shows the compressive strength of the concrete for easy reference. It was used as verification of the compressive strength of the tilt up panel. Pullout strength EA flexural strength Figure 6 4 illustrates the relationship of the pullout strength and the equivalent age maturity method. The relationship was developed using Microsoft Excel with the best fit curve being a logarithmic function. The secondary y axis shows the flexural s trength

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114 of the concrete for easy reference. It was used as verification of the flexural strength of the tilt up panel. Evaluation of Pullout Strength Maturity The pullout strength maturity relationships were used to estimate the strength of the lightweigh t concrete in the experimental batch. The relationships were ver ified to test their validities. Pullout Strength TTF Verification The pullout strength TTF relationships created in the control batch were used to estimate the compressive and flexural strengt h of the experimental batch concrete. Pullout strength TTF compressive strength verification Figure 6 5 demonstrates the verification data of the pullout strength in the experimental batch as a function of TTF. The figure also shows a 10% range of accept able results. The pullout strength taken at the side of the tilt up panel underestimated the compressive strength of the concrete due to radial cracks developed during testing. However the pullout strength determined at the surface of the tilt up slightly overestimated the compressive strength of the concrete, but within the 10% acceptable range. Pullout strength TTF flexural strength verification Figure 6 6 illustrates the verification data of the pullout strength in the experimental batch as a function of TTF. The figure also shows a 10% range of acceptable results. The pullout strength taken at the side of the tilt up panel underestimated the flexural strength of the concrete due to radial cracks developed during testing (Figure 5

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115 5) However the pullout strength taken at the surface of the tilt up panel slightly overestimated the flexural strength of the concrete, but within the 10% acceptable range. Pullout Strength EA Verification The pullout strength EA relationships created in the control batch were u sed to predict the compressive and flexural strength of the experimental batch concrete. Pullout strength EA compressive strength verification Figure 6 7 demonstrates the verification data of the pullout strength in the experimental batch as a function of EA. The figure also shows a 10% range of acceptable results. The pullout strength taken from the side of the tilt up panel underestimated the compressive strength of the concrete due to radial cracks developed during testing (Figure 5 5) However the pull out strength taken at the surface of the tilt up panel slightly overestimated the compressive strength of the concrete, but within the 10% acceptable range. Pullout strength EA flexural strength verification Figure 6 8 illustrates the verification data of the pullout strength in the experimental batch as a function of EA. The figure also shows a 10% range of acceptable results. The pullout strength taken at the side of the tilt up panel underestimated the flexural strength of the concrete due to radial crac ks developed during testing. However the pullout strength taken at the surface of the tilt up panel slightly overestimated the flexural strength of the concrete, but within the 10% acceptable range.

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116 Table 6 1. Pullout strength TTF control batch Time (Days) Time (hrs) Pullout strength (KN) Average TTF (C hrs) 1 24 6.3 540 3 70 12.1 1470 7 161 17.65 3242 14 331 19.1 6468 28 667 21.6 12803

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117 Figure 6 1. Pullout strength TTF compressive strength relationship, control batch y = 4.8743ln(x) 23.547 R = 0.9681 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 0 5 10 15 20 25 0 2000 4000 6000 8000 10000 12000 14000 Compressive Strength, psi Pullout Strength, KN TTF, (C hrs) Control Batch

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118 Figure 6 2. Pullout strength TTF flexural strength relationship, control batch y = 4.8743ln(x) 23.547 R = 0.9681 0 100 200 300 400 500 600 700 800 0 5 10 15 20 25 0 2000 4000 6000 8000 10000 12000 14000 Flexural Strength, psi Pullout Strength, KN TTF, (C hrs) Control Batch

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119 Table 6 2 Pullout stregth EA control batch Time (Days) Time (hrs) Pullout strength (KN) Calculated Equivalent Age (days) 1 24 6.3 540 3 70 12.1 1470 7 161 17.65 3242 14 331 19.1 6468 28 667 21.6 12803

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120 Figure 6 3 Pullout stregth EA compressive strength relationship, control batch y = 4.884ln(x) + 6.373 R = 0.9696 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 0 5 10 15 20 25 0.0 5.0 10.0 15.0 20.0 25.0 30.0 Compressive Strength, psi Pullout Strength, KN Equivalent Age at 20 Control Batch

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121 Figure 6 4. Pullout stregth EA flexural strength relationship, control batch y = 4.884ln(x) + 6.373 R = 0.9696 0 100 200 300 400 500 600 700 800 0 5 10 15 20 25 0.0 5.0 10.0 15.0 20.0 25.0 30.0 Flexural Strength, psi Pullout Strength, KN Equivalent Age at 20 Control Batch

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122 Figure 6 5. Ve rification of pullout strength TTF compressive strength relationship, experimental batch 0 1000 2000 3000 4000 5000 6000 0 5 10 15 20 25 30 0 2000 4000 6000 8000 10000 12000 14000 Compressive Strength, psi Pullout Strength, KN TTF, (C hrs) Experimental Batch, Tilt-up Sides Experimental Batch, Tilt-up Top 10%

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123 Figure 6 6. Ve rification of pullout strength TTF flexural strength relationship, experimental batch 0 100 200 300 400 500 600 700 800 900 0 5 10 15 20 25 30 0 2000 4000 6000 8000 10000 12000 14000 Flexural Strength, psi Pullout Strength, KN TTF, (C hrs) Experimental Batch, Tilt-up sides Experimental Batch, Tilt-up Top 10%

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124 Figure 6 7. Verification of pullout strength EA compressive strength relationship, experimental batch 0 1000 2000 3000 4000 5000 6000 0 5 10 15 20 25 30 0.0 5.0 10.0 15.0 20.0 25.0 30.0 Compressive strength, psi Pullout Strength, KN Equivalent Age at 20 Experimental Batch, Tilt-up Sides Experimental Batch, Tilt-up Top 10 %

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125 Fig ure 6 8. Ve rification of pullout strength EA flexural strength relationship, experimental batch 0 100 200 300 400 500 600 700 800 900 0 5 10 15 20 25 30 0.0 5.0 10.0 15.0 20.0 25.0 30.0 Flextural Strength, psi Pullout Strength, KN Equivalent Age at 20 Experimental Batch, Tilt-up Sides Experimental Batch, Tilt-up Top 10%

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126 CHAPTER 7 TILT UP PANEL DESIGN AND CONSTRUCTION Overview The design of the tilt up panel undergoes two engineering design considerations. The first is to d es ign the tilt up panel for service and ultimate loads. The second is to design the tilt up panel for the lifting stresses Although there are few references on designing the tilt up panel for lifting stresses, there is no reference found for lightweight con crete tilt up panel design for lifting stresses. Therefore, this research focused on investigating lightweight tilt up panel stresses during lifting. Panel Design The original design of the tilt up panel was analyzed in Abi using norm al density concrete (150 lb/ft 3 ) This research adopted the same design, approach but using structural lightweight concrete (117 lb/ft 3 ) for the sake of comparing the stresses developed in both panels during lifting ( Figure 7 1 ) ( Abi Nader 2010 ) The desig n consists of the following: Tilt up panel t hickness= 3.5 Inches 28 day compressive strength = 4000psi Compressive strength at day of lifting > 2500psi. Reinforcement #4 bars Two (2) Lifting inserts A 16 square feet opening Static s C omputation s Stat ic s calculations were performed to determine the maximum positive and negative moment due to lifting. Based on these maximum values of moments, strain gauges were mounted to monitor the change in lengths.

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127 Angle of Inclination The tilt up panel was consider ed as a simply supported beam with the maximum moment in the mid span (7 1) Where : W = Self weight of the panel L = Length of the panel For Tilt up panel, up panel and the casting surfa ce as the panel being lifted ( Figure 7 2 ) follows: (7 2) The maximum moment occurs when cos equals to 1, that is when equals to 0. This indicates that the maximum moment occurs when the tilt up panel is flat on the ground. Moment C omputation s in the Y Y D irection The tilt up panel was divided into three sections ( Figure 7 3 ) to calculate the weight of each section of the panel. The weight the sections were used to calculate the Maximum moments of the panel at zero degree. The Unit Weight of concrete used in these calculations is 1 17 lbs/ft which was the wet unit weight of the l ightweight concrete in the experimental batch W1 = Weight of section 1 W2= Weight of section 2 W3= Weight of section 3

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128 W1 = 10ft x 3.5in x 1 ft/in x 1 17 pcf = 341.25 lb/ft 12 W2 = 6ft x 3.5in x 1 ft/in x 117 pcf = 204.75 lb/ft 12 W3 = 10ft x 3.5in x 1 ft/in x 117 pcf = 341.25 lb/ft 12 The shear and moment diagrams for the tilt up panel in the Y Y direction are illustrated in ( Figure 7 4 ) Reaction at zero feet (A) is the reaction of the casting floor. It was calculated to be 784.9 lbs. acting upward. The reaction at 7 feet (B) is the reaction due to lifting. It was calculated to be 1,740.4 lbs. acting upward. Reaction B represents the vertical tension on the on the lifting inserts. Thus, each lifting insert underwent 870.2 lbs. of tension ( Figure 7 5 ). The moment diagram ( Figure 7 4 and Figure 7 5 ) shows a maximum positive moment of 1 ,094.8 ft lb at 3.17 feet. A negative moment at 7 feet amounts to 68 2.5 ft lb. at the inserts locations St resses C omputations in the Y Y D irection The stresses in the Y Y direction were calculated for the maximum moment at om according to the following equation : (7 3) Where : S b = Bending Stress (psi) M= Bending Moment (in lb) S x = Section Modulu s ( in)

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129 The section modulus is determined using the following equation (7 4) Where : S = Section Modulus (in) b= width of the section studied (in) d= Thickness of the panel (in) S = (10ft 4 ft) x 12 (in/ft) x (3.5in) = 147 in 6 S b = M/ S = 1,094.8 lb ft x 12(in/ft) = 89. 7 psi @ 3.17 147 in On the other hand, the stresses at 7 ft were calculated as follows: S x = bd = (10ft ) x 12 (in/ft) x (3.5in) = 245 in 6 6 S b = M/ S x = 682.5 lb ft x 12(in/ft) = 33.4 psi @ 7 ft. 245 in Moment Computation s in the X X Direction The tilt up panel was divided into three sections as shown in Figure to calculate the weight of each section of the panel. The weight the sections were used to c ompute the m aximum bending moments of the pan el at zero degree. The weight of the panel was divided into two sections along the zero shear point (3.17 ft from the bottom) The Unit Weight of the lightweight concrete is 117 lb/ ft W1 = Weight of section 1 W2= Weight of section 2 W3= Weight of section 3

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130 W1 = (9ft 3.17) x 3.5in x 1 ft/in x 1 17 pcf = 199 lb/ft 12 W2 = 4ft x 3.5in x 1 ft/in x 1 17 pcf = 136.5 lb/ft 12 W3 = (9ft 3.17ft) x 3.5in x 1 ft/in x 1 17 pcf = 199 lb/ft 12 Figure 7 7, shows the shear and moment diagrams for the tilt up panel in the X X direction. The P1 and P2 are the vertical tension values of the lifting inserts of 870.2 lb. as calculated earlier. Figure 7 8, shows a maximum negative moment of 488.9 ft lb. at the right insert. It also shows a maximum positive value of 300.1 lb ft at 4.38 feet from the left edge of the panel. The left insert has a negative moment value of 315.3 ft lb. St resses Calculations in the X X D irection Stresses at the lift and right inserts were the highest due to the maximum negative bending moments On the other hand, s tresses o ccurred along the inserts axis, 4.38 ft form the left edge o f the panel due to the maximum positive bending moment The stresses were calculated as follows: The stress at the right insert: S b = M/ S x = 4 88.9 lb ft x 12(in/ft) = 59.9 psi 4 ft x 12(in/ft) x 3.5/ 6 The stress at the left inse rt: S b = M/ S x = 3 15.3 lb ft x 12(in/ft) = 56.3 psi (9 3.17) ft x 12(in/ft) x 3.5/ 6 The stress at 4. 38 ft from the left edge : S b = M/ S x = 3 00.1 lb ft x 12(in/ft) = 36.8 psi 4 ft x 12(in/ft) x 3.5/ 6

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131 Static s C omputation s Using 1.5 Suction Factor Same concepts of the static s calculations were applied using a 1.5 suction factor to the weight of the panel. Moment C omputation s in the Y Y Direction with Suction The panel was divided into three s ections ( Figure 7 3 ) and the weight of each section is shown below. W1 = ( 10ft x 3.5in x 1 ft/in x 1 17 pcf ) x 1.5 = 512 lb/ft 12 W2 = ( 6ft x 3.5in x 1 ft/in x 117 pcf ) x 1.5 = 312 lb/ft 12 W3 = ( 10ft x 3.5in x 1 ft/in x 117 pcf ) x 1.5 = 512 lb/ft 12 The maximum positive moment of 1,666 lb ft occurred at 3.17 feet from the bottom of the panel. The maximum negative moment of 1,024 occurred at 7 feet where the inserts are located ( Figure 7 9 ) Stresses C omputation s in the Y Y Direction with Suction According to the maximum moments in the Y Y direction, the following stresses can be calculated: S b. = M/ S = 1,666 lb ft x 12(in/ft) = 136 psi @ 3.17 ft. 147 in S b = M/ S x = 1,024 lb ft x 12(in/ft) = 50.1 psi @ 7 ft. 245 in Moment C omputations in the X X Direction with Suction The panel was divide d into three regions. The weight of each region is calculated with a 1.5 suction factor below. W1 = ( (9ft 3.17) x 3.5in x 1 ft/in x 1 17 pcf ) x 1.5 = 298.5 lb/ft 12 W2 = ( 4ft x 3.5in x 1 ft/in x 1 17 pcf ) x 1.5 = 2 05 lb/ft 12 W3 = ( (9ft 3.17ft) x 3.5in x 1 ft/in x 1 17 pcf ) x 1.5 = 298.5 lb/ft 12

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132 In addition to the weight of the panel, 1,310 lbs. of upward force was applied to the panel dur ing lifting at each insert. The moment at the right insert was found to be negative 733.3 lb ft. The maximum positive moment occurred at 4.38 ft from the left with a value of 450.9 lb ft. The left insert had a negative moment of 472.9 lb ft ( Figure 7 10 ). Stresses Calculations in the X X Direction with Suction The maximum positive/ negative moments were applied to calculate the stresses as shown below: The stress at the right insert: S b = M/ S x = 733.3 lb ft x 12(in/ft) = 89.8 psi 4ft x 12(in/ft) x 3.5/ 6 The stress at the left insert: S b = M/ S x = 4 72.9 lb ft x 12(in/ft) = 84.4 psi (9 3.17) ft x 12(in/ft) x 3.5/ 6 The stress at 4. 38 ft from the left edge : S b = M/ S x = 45 0.9 lb ft x 12(in/ft) = 55.2 psi 4ft x 12(in/ft) x 3.5/ 6 Casting Mud S lab Florida. of the existing floor slab to achieve an acceptable leveled slab. The casting bed provided a smooth steel troweled finish to accommodate the tilt up panel requirements (Figure 7 11)

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133 Formwork and Steel R einforcement After the casting slab has fully cured and gained sufficient strength, the tilt up panel formwork was prepared using 2 x 4 wood studs. It provided the required thickness The formwork was drilled to allow for the temperature loggers wires to extend out. It was also used to fix the pull out inserts (Figure 7 12) Grade 60 steel reinforcements were used The size and location of the rebar in the tilt up panel were in accordance to Abi ( Figure 7 13 Figure 7 14 and Figure 7 15 ) The steel reinforcements were provided by Ge rdau AmeriSteel of Jacksonville, Florida. The steel reinforcements were placed and tied using rebar tie wires. The reinforcing steel mesh was removed by the overhead crane to allow for the bond breaker to be sprayed before it was placed back into positio n. One inch bolsters were used to support steel reinforcement at level 2 every 2 feet The following is a list of the steel bars used : 3 #4 rebar 0 ft 8in long, 3 #4 rebar 1 ft 8in long, 6 #4 rebar 3 ft 8in long, 4 #4 rebar 4 ft 0in long, 8 #4 re bar 8 ft 8in long, 8 #4 rebar 9 ft 8in long, and 8 #4 rebar 1ft 6in long. Lifting Inserts The lifting inserts were used at 7 feet from the bottom of the panel. The RL 24 two tone p late anchor s were used; they were provided by Meadow Burke. Each lifti ng insert was surrounded four 18 #4 rebar according to the manufacturer application manual ( Figure 7 16 )

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134 Bond Breaker A day before pouring the tilt up panel, J6WB Sure Lift by Dayton Superior was sprayed. The bond breaker was sprayed using a portable low pressure pump up sprayer ( Figure 7 17 ) It was applied by spraying the casting bed in rows, each with a 50% spray overlap. Each layer was applied perpendicular to the previous layer after allowing it to dry for more than 2 hours. The casting bed prepared showed a sign of high porosity when the bond breaker turned to white color. Therefore, as per the manufacturer recommendations third and fourth layers were applied to ensure a proper bondage break. Table 7 1 lists the chemical and physical properties of the J6WB Sure Lift bond breaker used in this research. The bond breaker was supplied by BNG Construction Company Tilt up Panel Casting H65BC lightweight concrete design mi x was supplied by Florida Rock Industries. The concrete was delivered in a truck as a wet mix ready to be poured ( Figure 7 18 ). Three temperature loggers were impeded in the concrete. Two loggers were located at 3.17 feet from the bottom, where the maximum moment in the Y Y direction was expected ( Figure 7 19 ) The third logger was placed between the lifting inserts at 7 feet from the bottom, where the positive moment in the X X direction was determined. I n addition, a pullout insert was placed at each side of the tilt up panel. Two were placed at 3.17 feet from the bottom and the others in mid span ( Figure 7 19 ) Another insert was inserted into the concrete surface at a location where it has minor effect on the panel as it was being lifted. Furthermore, two COMA meters were inserted into the panel while

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135 while the other was inserted in the one foot wi de strip below the opening of the panel (Figure 7 20) Strain Ga u ges Location Surface mount strain gauges were strategically fixed where the maximum positive/negative moments are expected based on the design calculations. A total of eight gauges were insta lled to monitor the strains that the concrete undergoes as the tilt up panel was being lifted. Five of them were vertically fixed in the direction of the Y axis and three horizontally in the X axis direction. Figure 7 21, shows th e location of the strain gauges. Lifting of Tilt up Panel At the day of lift, the lightweight concrete was tested for compressive and flexural strength as discussed ea rlier. A digital level was glued to the surface of the tilt up panel to indicate the ang le of inclination while lifting. The process was video recorded for later referencing. The stain gauges were connected to the data acquisition devices and synchronized to a computer via a USB cable. Software showing the real time strains and logs them in a file was employed ( Figure 7 22 ). The process of lifting the tilt up panel is shown in Figure 7 23

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136 Figure 7 1. Tilt up panel dimensions ( drawing courtesy of Adel Alsaffar)

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137 Figure 7 2. Angle of inc lination ( drawing courtesy of Adel Alsaffar)

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138 Figure 7 3. Tilt up panel sections to calculate moments in Y Y direction (drawing courtesy of Adel Alsaffar)

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139 Figure 7 4. Shear and moment diagram of tilt up panel at zero degree in Y Y direction (drawing courtesy of Adel Alsaffar)

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140 Figure 7 5. Maximum moments Y Y direction, at zero degree due to lifting ( drawing courtesy of Adel Alsaffar)

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141 Figure 7 6. Tilt up panel sections to calculate moments in X X direction (drawing courtesy of Adel Alsaffar)

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142 Figure 7 7. Shear and moment diagram of tilt up panel at zero degree in Y Y direction (drawing courtesy of Adel Alsaffar)

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143 Figure 7 8. Maximum moments X X direction, at zero degree due to lifting (drawing courtesy of Adel Alsaffar)

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144 Figure 7 9. Shea r and moment diagram, Y Y direction with suction (drawing courtesy of Adel Alsaffar)

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145 Figure 7 10. Shear and moment diagrams, X X direction with suction (drawing courtesy of Adel Alsaffar)

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146 A B Figure 7 11. Casting bed preparations A) formwork and plastic B) leveling and finishing ( p hoto courtesy of Adel Alsaffar) Figure 7 12. Tilt up panel formwork (photo courtesy of Adel Alsaffar)

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147 Figure 7 13. Steel reinforcement design ( Abi Nader 2010 ) Figure 7 14. Steel reinforcement levels ( Abi Nader 2010 )

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148 Figure 7 15. Tilt up panel steel re inforcement (photo courtesy of Adel Alsaffar)

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149 Figure 7 16. Lifting inserts and reinforcement (photo courtesy of Adel Alsaffar)

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150 Figure 7 17. Bond breaker being sprayed (photo courtesy of Adel Alsaffar)

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151 Table 7 1. Physical and Chemica l Properties of J6WB Sure Lift by Dayton Superior. General information Properties Form Liquid Color Red Odor Slight Change in condition : Melting point Boiling Point 212 F Flash point 484 F Auto Igniting not self igniting Danger of explosion Does not present an explosion hazard Vapor pressure at 68 F 17 mm Hg Density at 68 F 0.992g/cm Miscibility with water Not miscible or difficult to mix Solvent content : O rganic solvents 0.50% Water 90.40% Volatile Organic Compounds 88g/l

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152 Figure 7 18. Casting tilt up panel (photo courtesy of Adel Alsaffar) Figure 7 19. Maturity logger and pullout insert at 3.17 feet (photo courtesy of Adel Alsaffar)

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153 Figure 7 20. COMA meter being inserted into the fresh concrete (photo courtesy of Adel Alsaffar)

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154 Figure 7 21. Strain gauges locations (drawing courtesy of Adel Alsaffar)

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155 Figure 7 22. Stain gauge data acquisition devices links to a computer (photo courtesy of Adel Alsaffar)

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156 A B C D Figure 7 23. Tilt up lifting process A) Just before lifting B) Bond breaking C) 45 of inclination D) Upright (photo courtesy of Adel Alsaffar)

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157 CHAPTER 8 STRESS AND STRAIN ANALYSIS OF TILT UP PANEL DURING LIF T I NG Overview Surface mount strain gauges were instrumented on the panel to measure the actual elongation and contraction of the concrete due to bending moments during lifting. The obtained strains at different locations were converted to stress to compare r esults with static s calculations and software ones. The strains extracted from the field were also compared to those of a normal weight concrete panel performed in Abi research. ( Abi Nader 2010 ) Figure 8 1 shows the locations and labels of the strai n gauges on the tilt up panel The locations of the gauges w ere selected based on critical bending moment locations in each direction. Critical Angle of Inclination Results from manual s tatic s computations and commercial software output as well as the wor k performed by Abi Nader indicate that the maximum bending moments occur at zero degree angle of inclination. This means that maximum stresses/ strains occur just as the tilt up panel breaks off the casting slab ( Abi Nader 2010 ) Field St r ains Collection Figure 8 2 shows the overall strain measurements obtained during lif ting the tilt up panel. It depicts the cycle of lifting the panel from 0 90 degrees. The time of lifting is marked on the figure as the time of the panel being straight upward and back down. It can be observed that the maximum positive or negative strain s happen at zero degree angle.

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158 Table 8 1 shows the maximum value of strains recorded at zero degree of inclination. Positive strains indicate that the concrete was in tension at that location. In the contrary, negative strains reflect compression of the concrete surface at the gauge location. Modulus of Elasticity The modulus of elasticity was determined by measuring the compressive strength of the lightweight concrete cylinder and the corresponding strain in accordance to ASTM Standard ( ASTM C469 2010 ) Two st r ain gauges were glued to the sides of the concrete cylinder with a similar procedure as in the tilt up panel. They were connected to a computer via a data acquisi tion device ( Figure 8 3 ). The following equation was used to determine the modulus of elastic: E= (S 2 S 1 2 1 ) (8 1) Where: E = chord modulus of elasticity, psi S 2 = stress corres ponding to 40% of ultimate load ( psi ) S 1 1 (psi) 2 = longitudinal strain produced by stress S 2 (psi) 1 = longitudinal strain o f 5 0 micro strain (in/in) The compressive strength at the day of tilt was determined according to ASTM C 39 to be 3,989 psi. The value of S 2 was determined as 40% of the compressive strength at 1596 psi with a corresponding stain of 630 millionths. The str ess of 160 psi was determined for a strain of 50 millionths. Thus, the modulus of elasticity was calculated as follows:

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159 E = (1596 160) psi / (6.3 x 10 4 5.0 x 10 5 ) (in/in) = 2.475 x 10 6 psi Converting Strains to Stresses The following equation was us ed to calculate the stresses at certain locations of the tilt up panel using the modulus of elasticity of the lightweight concrete and the strains obtained from the strain gauges. E = S b / ( 8 2) Where: S b = Bending Stress (psi) (in/in) E= Modulu s of Elasticity (psi) The equation was rearranged to the following format: S b = E x (8 3) Table 8 2 shows the measured strains of the tilt up panel at zero degree inclination and the corresponding stresses. Stresses Comparison Table 8 3 lists the stresses of the lightweight concrete tilt up panel calculated from the surface mount strain gauges, calculated stresses with and without suction and stress determined by commercial software 1 and commercial software 2. Stresses with ne gative value s reflect the compressive stresses of the top surface of the panel. This is due to the positive moment exerted on the concrete. Positive moments should have been reflected as tension stresses acting on the lower surface of the panel. However, d ue to the inaccessibility of the bottom side of the panel and the neutral axes of the panel being through mid thickness, the tension stresses were measured as compressive stresses at the top surface of the panel.

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160 It can be concluded that the calculated str esses without the suction effect underestimated the actual stresses. On the other hand, the calcul ated stresses with an increase factor of 50 percent due to suction yielded a good estimat ion of the actual stres ses at zero inclination degree. Table 8 3 als o shows some discrepancies between the measure d and calculated stresses at gauge number 4, 5 and 7. These discrepancies can be attributed to the lifting mechanism. The tilt up panel under study was lifted using strap cables instead of a spread beam due to limited resources ( Figure 8 4 ) This has affected the stress distribution by increasing the compressive stresses at gauge number 5, which is located between the two lifters. It also affected the stresses in the reg ion around the lifting lugs However, the tilt up panel was designed for the overall maximum stresses ( at gauge number 1, 2 and 8 ) Figure 8 5, illustrates the stresses of the lightweight concrete panel. Stresses Lightweight versus Normal Concrete The l igh tweight concrete tilt up panel was designed exactly as the norma l weight concrete panel investigated previously by Abi Nader The aim was to compare the stresses due to lifting for both panels. Table 8 4 compares the lightweight tilt up panel stress es and stresses from the normal weight concrete tilt up panel The stress results are listed side by side for studying the comparison purposes By c omparing both types of concrete, it can be concluded that the lightweight concrete panel experienced lower stresse s. This is due to its lower density, despite the fact that it has a lower modulus of elasticity. Figure 8 6, depicts stresses in tilt up wall for both types of concrete tilt up wall panels The stresses and strains of lightweight versus normal concrete til t up wall panels were also calculated using basic statics to show the ir relationship s Equation 8 3 was

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161 rearrange d by dividing the stresses of the lightweight concrete (LWC) by the stresses of the normal concrete (NC) as follows: Where: E(LWC) = 2.48 x 10 6 psi (measured) E(NC) = 3.84 x 10 6 psi (measured in Abi Nader research) Hence, = 0.77 = 1.18 This shows that for same strength of concrete, the lightweight concrete tilt up wall panel experienced 18% more strain during lifting, but the stresses were 23% less than stresses in the normal weight concrete tilt up wall panel Since lightweight concrete has lower stiffness than normal weight concrete, concerns were also raised as to th e structural effectiveness of the lightweight tilt up panel as an element of a structure or a building. Therefore, Appendix B shows an example of a 31 ft x 15 ft tilt up panel. The panel design example was illustrated in ACI 551.2R 10 for normal weight con crete. With simple substitutions of lightweight concrete properties, ultimate was calculated and compared to normal concrete.

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162 It was concluded that for all three load cases the lightweight concrete panel exerted less than the normal concrete wall. There fore, the lightweight concrete outperformed the normal concrete during and after tilting.

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163 Figure 8 1. Surface mount strain gauge locations (drawing courtesy of Adel Alsaffar)

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164 Figure 8 2. Strain measurements during tilt up panel lifting Table 8 1 Maximum strain at zero degree of inclination Strain Gauge No. Maximum Strain (in/in) 1 5.4 x 10 5 2 5.8 x 10 5 3 1.4 x 10 5 4 2.0 x 10 6 5 4.3 x 10 5 6 1.9 x 10 5 7 4.0 x 10 6 8 5.2 x 10 5

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165 Figure 8 3. Modulus of elasticity test (phot o courtesy of Adel Alsaffar) Table 8 2. Stresses calculations Strain Gauge No. Maximum Strain (in/in) Stresses (psi) 1 5.4 x 10 5 133.66 2 5.8 x 10 5 143.56 3 1.4 x 10 5 34.65 4 7.0 x 10 6 17.33 5 4.3 x 10 5 106.43 6 1.9 x 10 5 47.03 7 1.0 x 10 5 24.75 8 5.2 x 10 5 128.71

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166 Table 8 3. Stress comparison of lightweight concrete tilt up panel Strain Gauge No. Measured stresses (psi) Calculated stresses no suction (psi) Calculated stresses suction (psi) Commercial Software 1 (psi) Commerc ial Software 2 (psi) 1 133.7 89.7 136.0 112.0 88.2 2 143.6 89.7 136.0 112.0 88.2 3 34.7 38.6 57.9 24.0 26.9 4 17.3 56.3 84.4 45.0 32.8 5 106.4 36.8 55.2 44.0 25.2 6 47.0 59.9 89.8 50.0 56.3 7 24.8 33.4 50.1 45.0 32.8 8 128.7 89.7 136.0 112.0 88.2 Figure 8 4. Strap cables lifting at 45 degree angle (photo courtesy of Adel Alsaffar)

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167 Figure 8 5. Tilt up panel stress comparison Table 8 4. Stress comparison of lightweight versus normal concrete Strain Gauge No. Measured Stresses (lightweight c oncrete) (psi) Measured Stresses (normal concrete) (psi) 1 133.7 154 2 143.6 157 3 34.7 77 4 17.3 54 5 106.4 61 6 47.0 92 7 24.8 46 8 128.7 165 0 20 40 60 80 100 120 140 160 1 2 3 4 5 6 7 8 Tensile Stresses (psi) Stress Locations Measured Stresses Statics Calculation Statics Calculation with suction Commercial Software 1 Commercial Software 2

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168 Figure 8 6. Stress comparison of lightweight versus normal concrete 0 20 40 60 80 100 120 140 160 180 1 2 3 4 5 6 7 8 Tensile Stresses (psi) Stress Location Lightweight Concrete Tensile Stresses Normal Concrete Tensile Stresses, Abi-Nader

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169 CHAPTER 9 CONCL U SION S AND RE COMM E NDATIONS Conclusion s All maturity methods were found effective in estimating the compressive and flexural strength of the lightweight concrete tilt up panel. However, the equivalent age factor method was the most accurate one followed by the temperature time factor. The COMA meter method was also effective but it underestimated the strength of the concrete. Nevertheless, for the purpose of tilt up construction it was found within an acceptable range. Despite the effectiveness of the maturity methods, ASTM C 1074 requires different concrete strength estimation tests to be executed before performing a critical operation, in ou r case lifting a tilt up panel. The pullout strength test method was used and found effective in estimating the compressive and flexural strength of the lightweight concrete tilt up panel. However, the pullout inserts must be place on the surface of the pa nel for an accurate estimation. Side pullout inserts used in our experiment have failed to yield a good estimation of the strength due to the slenderness of the panel. The maturity m ethods and pullout strength test relationships were investigated and found to be very effective in predicting the strength of the lightweight concrete and can be utilized in different applications such as tilt up panels. Furthermore, the tilt up panel surface mount strain gauges have shown that maximum stresses occur at zero deg ree of inclination, when the tilt up just breaks free off the casting bed. A suction factor of 50% must be considered in the computations of the maximum negative or positive bending moment s in order to obtain an accurate

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170 panel design. The lightweight concr ete was found structurally effective in the construction of the tilt up panel despite the lower modulus of elasticity. Recommendations The application of lightweight concrete in tilt up constructions. Evaluate the compressive and flexural strength of con crete using the Equivalent Age method. Applying pullout inserts to the surface of the tilt up panel. The used of Maturity Methods with Pullout strength test to evaluate the strength of lightweight concrete prior to lifting. Re evaluate the lifting software using data obtained in this research. Using 50% suction factor at zero inclination degree Study the suction effect on tilt up panel for a better understanding. Study the stresses in til t up panel with two layers of reinforcement Study the application of more non destructive testi ng to evaluate the strength of lightweight concrete. Study the application of lightweight coarse and fine aggregates in tilt up panel.

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171 APPENDIX A TEMPERATURE AND TIME DATA RECORD ED BY MATURITY LOGGERS Figure A 1. Temperature vs. Time of logger embedded in beam 1, control batch

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172 Figure A 2. Temperature vs. Time of logger embedded in beam 2, control batch

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173 Figure A 3. Temperature vs. Time of logger embedde d in cylinder 1, control batch

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174 Figure A 4. Temperature vs. Time embedded in cylinder 2, control batch

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175 Figure A 5. Temperature vs. Time of logger embedded in cylinder 1, experimental batch

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176 Figure A 6. Temperature vs. Time of logger 1 embedded in tilt up wall panel, experimental batch

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177 Figure A 7 Temperature vs. Time of logger 2 embedded in tilt up wall panel, experimental batch

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178 APPENDIX B COMMERCIAL SOFTWARE RESULTS Commercial Software 1

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181 Commer cial Software 2

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184 APPENDIX C DESIGN CO MPARISON OF LIGHTWEIGHT AND NORMAL WEIGHT CONCRETE TILT UP WALL PANELS Load Case 1: 1.2 D + 1.6 Lr + 0.8 W Table C 1. Tilt up panel design comparison for load case 1 Calculation Normal Concrete Lightweight Concrete Pua 20.6 k 20.6k Pum 43.4 k 38.2 k w u 0.204 klf 0.204 klf Pum/Ag 38.6 psi 33.9 psi Ase 7.72 in2 7.63 in2 a 0.757 in 0.749 in c 0.891 in 0.881 in c/d 0.285 0.281 Icr 353 in4 494 in4 Mcr 46.3 ft k 39.4 ft k 95.5 ft k 94.7 ft k Kb 97.4 k 93.8 k Mua 24.8 ft k 24.8 ft k Mu Mn 10.0 in 9.2 in

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185 Load Case 2: 1.2D + 0.5 Lr + 1.6W Table C 2. Tilt up panel design comparison for load case 2 Calculation Normal Concrete Lightweight Concrete Pua 12.4 k 20.6k Pum 35.2 k 29.91 k wu 0.408 klf 0.408 klf Pum/Ag 31.3 psi 26.6 psi Ase 7.59 in2 7.50 in2 a 0.744 in 0.735 in c 0.875 in 0.865 in c/d 0.280 0.276 Icr 349 in4 489 in4 Mcr 46.3 ft k 39.4 ft k 94.0 ft k 93.2ft k Kb 96.4 k 93.0 k Mua 54.9 ft k 45.9 ft k Mu 14.8 in 13.83 in

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186 Load Case 3: 0.9D + 1.6W Table C 3. Tilt up panel design comparison for load case 3 Calculation Normal Concrete Lightweight Concrete Pua 6.48 k 6.48 k Pum 23.6 k 19.6 k wu 0.408 klf 0.408 klf Pum/Ag 21.0 psi 17.4 psi Ase 7.39 in2 7.33 in2 a 0.725 in 0.72 in c 0.853 in 0.845 in c/d 0.273 0.270 Icr 344 in4 484 in4 Mcr 46.3 ft k 39.4 ft k 91.9 ft k 91.4 ft k Kb 95.1 k 92.0 k Mua 45.2 ft k 45.2 ft k Mu 11.4 in 11 in

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187 LIST OF REFERENCES Abi Nader, G. G. (2010). Erection stresses in reinforced concrete tilt up wall panels. Design, Constru ction and Planning University of Florida. ACI.213 (2003). Guide for Structural Lightweight Aggregate Concrete. Detroit, MI, American Concrete Institue. ACI 213R03. ACI.228 (2003). In Place Methods to Estimate Concrete Strength, American Concrete Insti tue. ACI 228.1R 03. ACI.308 (2001). Guide to Curing Concrete. Detroit, MI, American Concrete Institue. ACI 308R 01. ACI.318 (2011). Building Code Requirements for Structural Concrete. Detroit, MI, American Concrete Institute. ACI.551 (2010). Design G uide for Tilt Up Concrete Panels. Farmington Hills, MI, American Concrete Institute. ACI 551.2R 10. ASTM C39 (2011a). Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens. West Conshohocken, PA ASTM International. C39/C39M 11a. ASTM C78 (2010). Standard Test Method for Flexural Strength of Concrete (Using Simple Beam with Third Point Loading). West Conshohocken, PA, ASTM International. C78/C78M 10. ASTM C143 (2005). Standard test method for slump of hydraulic cement concrete West Conshohocken, PA, ASTM International. C143/C143M 05. ASTM C173 (2001). Standard Test Method for Air Content of Freshly Mixed Concrete by the Volumetric Method. West Conshohocken, PA, ASTM International. C 173/C 173M 01. ASTM C192 (2007). Stand ard Practice for Making and Curing Concrete Test Specimens in the Laboratory. West Conshohocken, PA, ASTM International. C 192 / C192M 07. ASTM C330 (2009). Standard Specification for Lightweight Aggregates for Structural Concrete. West Conshohocken, P A, ASTM International. C330/C330M 09 ASTM C469 (2010). Standard Test Method for Static Modulus of Elasticity and International. C469/C469M 10.

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188 ASTM C567 (2005a). Standard Test M ethod for Determining Density of Structural Lightweight Concrete. West Conshohocken, PA, ASTM International. C567 05a ASTM C900 (2006). Standard Test Method for Pullout Strength of Hardened Concrete. West Conshohocken, PA, ASTM International. C900 06. ASTM C1074 (2011). Standard Practice for estimating Concrete Strength by Maturity Method. West Conshohocken, PA, ASTM International. C1074 11. Carino, N. J. (2008). Concrete Construction Engineering Handbook CRC Press. Greatbuildings.com (2012). Re trieved May, 2012. Hansen, A. J. (1982). "COMA meter, the Mini Maturity Meter." Reprint from Nordisk Betong Harrison, T. (2003). "Concrete properties: setting and hardening." Advanced concrete technology: Concrete properties 2 (66): 64. http://www.norliteagg.com/internalcuring/ (2012). Retrieved May 2012. IAEA (2002). "Guidebook on non destructive testing of concrete structures." The International Atomic Energy Agency No. 17. Johnson, M. (2 002). Tilt Up Pioneer Robert Aiken developed tilt up construction nearly 100 years ago. Concrete Construction Hanely Wood, LLC Lamond, J. F. (2006). Significance of tests and properties of concrete and concrete making materials ASTM International. Na wy, E. G. and H. Nassif (2008). Long Term Effects and Serviceability. C oncrete Construction Engineering Handbook Edward G. Nawy. Boca Raton, FL, CRC Press. Nixon, J. M. M., A. K. Schindler, et al. (2008). Evaluation of the Maturity Method to Estimate Co ncrete Strength in Field Applications, Auburn University. Stone, W. C., N. J. Carino, et al. (1986). "Statistical methods for in place strength predictions by the pullout test." 83. Superior, D. (2009). TILT UP CONSTRUCTION PRODUCT HANDBOOK. D. Superi or. TCA (2011). T he Architecture of Tilt up Mount Vernon, IA, Tilt up Concrete Association. TCA (2011). The Construction of Tilt up Mount Vernon, IA, Tilt up Concrete Association.

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189 BIOGRAPHICAL SKETCH Adel Alsaffar was born in Kuwait City, Kuwait. He received his education in Kuwait until graduated from high school. He jo ined the University of Miami, FL for his b degree. He graduated with double majors in Civil and Architectural Engineering in 1999. He returned to his homeland and worked for Kuwait Oil Company for more than five years, during which he received his m University. After showing interest in higher education and research, he got awarded a scholarship from Kuwait University to continue his higher education. In 2005, he joined the School of Building Construction and graduated with a m He then joined the Ph.D program at the College of Design Construction and Planning at the University of Fl orida. Prior to completing his PhD requirements, Adel obtained another m