Segregation of Post-Tensioning Grout during Full Scale Mixing and Injection

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Title:
Segregation of Post-Tensioning Grout during Full Scale Mixing and Injection
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1 online resource (123 p.)
Language:
english
Creator:
Randell, Alexander J
Publisher:
University of Florida
Place of Publication:
Gainesville, Fla.
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Thesis/Dissertation Information

Degree:
Master's ( M.E.)
Degree Grantor:
University of Florida
Degree Disciplines:
Civil Engineering, Civil and Coastal Engineering
Committee Chair:
HAMILTON,HOMER ROBERT,III
Committee Co-Chair:
FERRARO,CHRISTOPHER CHARLES
Committee Members:
CONSOLAZIO,GARY R

Subjects

Subjects / Keywords:
bridges -- corrosion -- duct -- grout -- post-tensioning -- steel
Civil and Coastal Engineering -- Dissertations, Academic -- UF
Genre:
Civil Engineering thesis, M.E.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract:
Post-tensioning (PT) tendons are typically composed of bundles of prestressing strand that are placed inside a duct, which is filled with a cementitious grout to bond the strand to the concrete and provide corrosion protection.  These PT tendons are typically used to reinforce segmental or I-girder bridge superstructures. In2000, FDOT found multiple failed tendons due to corrosion in bridges including the Mid-Bay Bridge, and the Niles Channel Bridge in the Florida Keys. CITATION Jef12 \l 1033  (Pouliotte, 2012) Since then,prepackaged, high performance grouts have been used to fill PT tendons.  Several relatively new ( Post-tensioned concrete bridge construction has a long history of reliable and relatively problem-free performance.  Soft grout, however, has serious implications and warrants investigation.  The research presented in this thesis is focused on the use of an inclined tube to test forthe formation of soft grout in commercially available prepackaged PT grouts and plain grouts with fillers (Portland cement and ground limestone).  The inclined tube test was adopted from a Euronorm test that is used to detect segregation and bleed.  As part of this research, a test was developed for the more specific use of detecting the potential for soft grout production.  Specifically, mass of soft grout was measured and moisture content of hardened grout in several locations along the length of the specimen was measured. Prepackaged PT grouts were tested at the manufacturer’s maximum specified water to solids ratio, as well as 15% extra mixing water.  Plain grouts, which were composed of Portland cement, calcium carbonate filler, and high-range water reducer, were also tested at varying water to cement ratios and filler content to determine the effect fillerhad on the formation of soft grout.  HRWR dosage was adjusted to maintain a constant grout viscosity. Inclined tube testing showed that when soft grout occurred, it would form at the top of the incline near the discharge of the specimen, indicating that segregation was the primary mechanism of development.  Tests on the prepackaged high performance PT grouts showed that only one type of grout produced soft grout when excess water was used in the mixture.  Tests on the plain grouts revealed that the formation of the soft grout material near the exit was highly sensitive to the percentage of filler material present in the mixture. The soft grout versus water to solids ratio curve for plain grout with and without filler shows that when fillers are used in combination with HRWR admixtures to achieve workability at low water to solids ratios, the sensitivity to formation of soft grout is increased substantially. Based on these findings, it can be concluded that using large percentages of filler material in combination with HRWR admixtures to achieve low water to solids ratios increases the likely hood of soft grout formation. It is recommended that additional filler material not be allowed in high performance PT grouts.
General Note:
In the series University of Florida Digital Collections.
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Includes vita.
Bibliography:
Includes bibliographical references.
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Description based on online resource; title from PDF title page.
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This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility:
by Alexander J Randell.
Thesis:
Thesis (M.E.)--University of Florida, 2013.
Local:
Adviser: HAMILTON,HOMER ROBERT,III.
Local:
Co-adviser: FERRARO,CHRISTOPHER CHARLES.

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UFRGP
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Applicable rights reserved.
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lcc - LD1780 2013
System ID:
UFE0046416:00001


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SEGREGATION OF POST-TENSIONING GROUT DURING FULL SCALE MIXING AND INJECTION By ALEXANDER RANDELL A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORID A IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF ENGINEERING UNIVERSITY OF FLORIDA 2013

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2013 A lexander R andell

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To my mother, Dr. Andrea Randell, MD, and my father Dr. Wallace Randell, DVM

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4 ACKNOWLEDGMENTS I thank the Florida Departm ent of Transportation (FDOT) State Materials Office and Structural Lab for their support in mate rials testing assistance with experimental testing. I would also like to thank Dr. H.R. Hamilt on, Dr. G.R. Consolazio, Dr. C. Ferraro, Richard DeLorenzo, Patrick Carlton, Max McGahan, Brett Brunner, Kunal Malpani, Marlo Chumioque, Shelby Brothers, Sai Ji ang, Matt Brosman, and Amanda Sanyigo for helping with the experimental testing and report.

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5 TABLE OF CONTENTS page ACKNOWLEDGMENTS .................................................................................................. iv LIST OF TABLES ............................................................................................................ 7 LIST OF FIGURES .......................................................................................................... 8 LIST OF DEFINITIONS ................................................................................................ 12 LIST OF ABBREVIATIONS ........................................................................................... 14 CHAPTER 1 INTRODUCTION .................................................................................................... 17 2 LITERATURE REVIEW .......................................................................................... 19 3 OBJECTIVE AND APPROACH .............................................................................. 26 4 MATERIALS ........................................................................................................... 28 Plain Grout .............................................................................................................. 28 Portland Cement .............................................................................................. 28 Filler Material .................................................................................................... 29 High Range Water Reducing Admixtures ......................................................... 29 Prepackaged PT Grouts ......................................................................................... 30 5 MIXING EQUIPMENT AND PROCEDURES .......................................................... 33 Colloidal Grout Plant ............................................................................................... 33 PT Grout Mixing Procedure .............................................................................. 33 Plain Grout Mixing Procedure ........................................................................... 34 6 TEST METHODS .................................................................................................... 38 Inclined Bleed test .................................................................................................. 38 Modified Flow Cone ................................................................................................ 39 Unit Weight ............................................................................................................. 39 Mud Balance ........................................................................................................... 40 Pressure Bleed Test ............................................................................................... 40 Apparent Viscosity Test .......................................................................................... 41 Bleed Water Measurement ..................................................................................... 41 Soft Grout Identification and Measurement ............................................................. 42 Moisture Content .................................................................................................... 42

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6 7 RESULTS AND DISCUSSION ............................................................................... 54 Ap parent Viscosity Control ...................................................................................... 54 Representative Test Results ................................................................................... 55 Soft Grout ............................................................................................................... 56 Characterization and Measurement ................................................................ 56 Variation with Filler ........................................................................................... 59 Moisture content ..................................................................................................... 60 Plain Grout ....................................................................................................... 60 Prepackaged PT grout ..................................................................................... 60 Bleed ....................................................................................................................... 61 HRWR and Segregation ......................................................................................... 62 8 PLAIN GROUT AND PT GROUT COMPARISON .................................................. 85 9 SUMMARY AND CONCLUSIONS .......................................................................... 94 Co nclusions from High Performance Prepackaged PT Grout Testing .................... 95 Conclusions from Plain Grout Testing .................................................................... 96 Recommendations .................................................................................................. 96 APPENDIX A MOISTURE CONTENTS ........................................................................................ 99 B MOISTURE CONTENTS: ADDITIONAL TESTS .................................................. 102 C MOISTURE CONTENTS: PT GROUTS ............................................................... 103 D PLAIN GROUT DATA ........................................................................................... 106 REFERENCES ............................................................................................................ 121 BIOGRAPHICAL SKETCH .......................................................................................... 123

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7 LIST OF TABLES Table page 4-1 Summary of Plain Grout ..................................................................................... 31 4-2 Summary of PT grout PSA ................................................................................. 31 7-1 Representative Sample: Prepackaged PT grout ................................................. 65 7-2 Representative Sample: Plain grout ................................................................... 66 7-3 Soft grout summary ............................................................................................ 67 D-1 Plain grout summary (0% filler) ......................................................................... 109 D-2 Plain grout summary (35% filler) ....................................................................... 111 D-3 Plain grout summary (45% filler) ....................................................................... 113 D-4 PT results (1) .................................................................................................... 116 D-5 PT Results (2) ................................................................................................... 118

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8 LIST OF FIGURES Figure page 4 1 Particle size distribution for Portland cement ................................ ...................... 31 4 2 Particle size distribution for calcium carbonate ................................ ................... 32 5 1 Chemgrout CG600 E/H 3CL6 Progressive cavity pump ................................ .. 35 5 2 Add water to mixing basin ................................ ................................ .................. 35 5 3 Add one bag of grout at a time ................................ ................................ ........... 36 5 4 Scrape the inside of the mixing basin ................................ ................................ 36 5 5 Transfer the grout to the agitation tank ................................ ............................... 37 5 6 Pump grout to target ................................ ................................ ........................... 37 6 1 Inclined test tube schematic ................................ ................................ ............... 43 6 2 Inclined test tube picture ................................ ................................ ..................... 43 6 4 ASTM C939 Modified Flow Cone test ................................ ................................ 44 6 5 Unit weight cup and glass plate ................................ ................................ .......... 45 6 6 ................................ ................................ ......... 45 6 7 Schupack Pressure Bleed Test ................................ ................................ .......... 46 6 8 Schupack pressure bleed test components ................................ ........................ 46 6 9 Dynamic Shear Rheometer ................................ ................................ ................ 47 6 10 Helical ribbon and cup ................................ ................................ ........................ 47 6 11 Helical Ribbon Schematic ................................ ................................ ................... 48 6 12 DSR Cup Schematic ................................ ................................ ........................... 49 6 13 P T4 6 Soft Grout ................................ ................................ ................................ 50 6 14 Inclined Test Tube Sampling Locations ................................ .............................. 50 6 15 Moisture content scale ................................ ................................ ........................ 51 6 16 Moisture content samples ................................ ................................ ................... 51

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9 617 Moisture content samples inside oven ................................................................ 52 618 Band saw used during dissection ....................................................................... 52 619 Jack hammer used during dissection ................................................................ 53 7-1 HRWR admixture dosage ................................................................................... 68 7-2 Resulting initial viscosities .................................................................................. 68 7-3 Resulting initial flow cones ................................................................................. 69 7-4 Moist clay like soft grout with darker coloration .................................................. 70 7-5 PT4-6 Soft Grout ................................................................................................ 71 7-6 PT4-6 Soft Grout ................................................................................................ 71 7-7 C675-45 Soft Grout ............................................................................................ 71 7-8 C35-0 Soft Grout ................................................................................................ 72 7-9 C35-0 Soft grout being squeezed together ......................................................... 72 710 C35-35 Hardened Grout ..................................................................................... 73 711 C675-35 Large void due to bleed water .............................................................. 73 712 Segregation canal at top of cross-section ........................................................... 74 713 Segregation canal at top of cross section (PT grout) .......................................... 74 714 Soft grout located in segregation canal .............................................................. 74 715 Equator line separating hard cement from soft grout .......................................... 75 716 Equator line separating hard cement from soft grout (PT grout) ......................... 75 717 Soft grout vs. water to cement ratio .................................................................... 76 718 Soft grout vs. water to solids ratio ....................................................................... 76 719 Moisture content (0% filler) ................................................................................. 77 720 Moisture content (35% filler) ............................................................................... 77 721 Moisture content (45% filler) ............................................................................... 78 722 Moisture contents (mixed at maximum water to solids ratio) .............................. 78

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10 723 Moisture contents (mixed at 15% extra water to solids ratio) ............................. 79 724 Comparison of inclined bleed and pressure bleed measurements with respect to w/c ..................................................................................................... 79 725 Comparison of inclined bleed and pressure bleed measurements with respect to water to solids ratio ............................................................................ 80 726 Moisture content C45-0 ...................................................................................... 80 727 Moisture content C67535 .................................................................................. 81 728 Moisture content C82545 .................................................................................. 81 729 Bleed water for mixes with and without HRWR admixture .................................. 82 730 Soft grout for mixes with and without HRWR admixture ..................................... 82 731 Apparent viscosity for mixes with and without HRWR admixture ........................ 83 732 Maximum moisture content versus water/HRWR ratio ....................................... 83 733 Bleed water versus water/HRWR ratio ............................................................... 84 734 Soft grout versus water/HRWR ratio ................................................................... 84 8-1 HRWR admixture/flow cone time versus w/s ratio (including PT4-6 tests) ......... 89 8-2 Flow cone time versus water to solids ratio (including all PT grouts) .................. 89 8-3 HRWR admixture/apparent viscosity versus w/s ratio (including PT4-6 tests) ... 90 8-4 Apparent viscosity versus water to solids ratio (including all PT grouts) ............. 90 8-5 Soft grout versus w/s ratio for varying amounts of filler (including PT4-6 tests) 91 8-6 Moisture contents for tests with no soft grout (left: PT grout, right: Plain grout) .. 91 8-7 Moisture contents for tests with soft grout (left: PT grout, right: Plain grout) ...... 92 8-8 Unit weight (left) and mud balance (right) versus water to solids ratio ................ 92 8-9 Unit weight versus water to solids ratio (including all PT grouts) ........................ 93 810 Mud balance versus water to solids ratio (including all PT grouts) ..................... 93 9-1 Bleed and segregation mechanism .................................................................... 98 A-1 C30-0 (left), C35-0 (right) ................................................................................... 99

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11 A-2 C45-0 (left), C55-0 (right) ................................................................................... 99 A-3 C675-0 (left), C825-0 (right) .............................................................................. 100 A-4 C35-35 (left), C45-35 (right) .............................................................................. 100 A-5 C55-35 (left), C675-35 (right) ............................................................................ 100 A-6 C825-35 (left), C45-45 (right) ............................................................................ 101 A-7 C55-45 (left), C675-45 (right) ............................................................................ 101 A-8 C82545 ............................................................................................................ 101 B-1 C55-45 (100 mL HRWR) (left), C45-0 (0 mL HRWR) (right) ............................. 102 B-2 C675-35 (0 mL HRWR) (left), C825-45 (0 mL HRWR) (right) ........................... 102 C-1 PT 1-4 maximum water (left), PT 1-4 15% extra water (right) ........................... 103 C-2 PT2-4 maximum water (left), PT2-4 15% extra water (right) ............................ 103 C-3 PT3-3 maximum water (left), PT3-3 15% extra water (right) ............................ 104 C-4 PT4-6 maximum water (left), PT4-6 15% extra water (right) ............................ 104 C-5 PT5-1 maximum water (left), PT5-1 15% extra water (right) ............................ 104 C-6 PT6-1 maximum water (left), PT6-1 15% extra water (right) ............................ 105 D-1 Flow cone vs. water to solids ratio (left), Grout temperature: 0% filler (right) ... 106 D-2 Grout temperature: 35% filler (left), Grout temperature: 35% filler (right) ......... 106 D-3 Grout temperature: 45% filler (left), Grout temperature: 45% filler (right) ......... 107 D-4 Mud balance: 0% filler (left), Mud balance: 35% filler (right) ............................. 107 D-5 Mud balance: 35% filler (left), Mud balance: 45% filler (right) ........................... 107 D-6 Mud balance: 45% filler (left), Unit weight: 0% filler (right) ............................... 108 D-7 Unit weight: 35% filler (left), Unit weight: 35% filler (right) ................................ 108 D-8 Unit weight: 45% filler (left), Unit weight: 45% filler (right) ................................ 108

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12 LIST OF DEFINITIONS Apparent viscosity The shear stress reading obtained from a rheometer divided by the shear rate at which the sample is being tested. For a Bingham paste mixture, it is the slope of the shear rate versus shear stress linear curve. Blast furnace slag T he nonmetallic product consisting essentially of silicates and aluminosili cates of calcium and other bases that develops in a molten condition simultaneously with iron in a blast furnace. (318, 2013) Bleed water When water that was initially mixed with grout powder segregates to the free surface of the grout during initial hydration of the cement particles. For the inclined tube, bleed water is almost exclusively found at the top of the inclined tube. The bleed water that initially segregates will sometimes be re absorbed as the cement material hydra tes further. Calcium carbonate Pulverized limestone (CaCO 3 ) which is used as an aggregate or Colloidal mixer A mixer designed to produce colloidal grout. (318, 2013) Fly ash The finely divided residue that results from the combustion of ground or powdered coal, and that is transported by flue gasses from the combustion zone to the particle removal system (318, 2013) Grout A mixture of cementitous materials, water, supplemental cementitous materials, aggregates, and chemical admixtures High range water reducing admixture A water reducing admixture capable of producing large water reduction or great flowability without causing undue set retardation or entrainment of air in mortar or concrete. (318, 2013) Silica fume V ery fine noncrystalline silica produced in electric arc furnaces as a byproduct of the production of elemental silicon or alloys containing silicon (318, 2013) Soft grout Unreacted, gelatinous wet material that is caused by excessive segregation of the PT grout components after injection has occurred.

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13 Supplementa ry cementitious material I norganic material such as fly ash, silica fume, metakaolin, or slag cement that reacts pozzolanically or hydraulically. (318, 2013) Tendon A n assembly consisting of a tensioned element (such as a wire, bar, rod, str and, or a bundle of these elements) used to impart compressive stress in concrete, along with any associated components used to enclose and anchor the tensioned element (318, 2013) Thixotropic grout The decrease in viscosity of a grout over time while undergoing a constant shear rate

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14 LIST O F ABBREVIATIONS HRWR High range water reducing admixture which is used to modify the fluid characteristics of PT grouts and is informally known as a superplastisizer. PSA Particle size analysis. Analysis conducted on powder using a laser diffraction particle size machine to determine the mean and standard deviation particle size of the powder w/c Water to cement ratio. The ratio of the weight of water to the weight of cement powder. w/s Water to solids ratio. The ratio of the weight of water to the weight of solid powder material.

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15 Abstract of Thesis Pres ented to the Graduate School of the University of Florida in Partial Fulf illment of the Requirements for t he Degree of Master of Engineering SEGREGATION OF POST-TENSIONING GROUT DURING FULL SCALE MIXING AND INJECTION By Alexander Randell December 2013 Chair: H.R. Hamilton Major: Civil Engineering Post-tensioning (PT) tendons are typically composed of bundles of prestressing strand that are placed inside a duct, which is filled with a ce mentitious grout to bond the strand to the concrete and prov ide corrosion protection. These PT tendons are typically used to reinforce segmental or I-girder br idge superstructures. In 2000, FDOT found multiple failed tendons due to corrosion in br idges including the Mid-Bay Bridge, and the Niles Channel Bridge in the Florida Keys. (P ouliotte, 2012) One caus e of this corrosion has been identified as soft grout, which is unreacted gelatinous putty grout. The research presented in this thesis is focused on the use of an inclined tube to test for the formation of soft grout in commercially available prepackaged PT grouts and plain grouts with fillers (Por tland cement and ground limestone). The inclined tube test was adopted from a Euronorm test that is used to detect segregation and bleed. Prepackaged PT grouts were tested at the manufacturers maximum specified water to solids ratio, as well as 15% extra mixing water. Plain grouts were also tested at varying water to cement ratios and filler content to determine the effect filler had on the formation of soft grout.

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16 T esting showed that when soft grout occurred, it would form at the top of the incline near the discharge of the specimen, indicating that segregation was the primary mechanism of development T ests on the prepackaged high performance PT grouts show ed that only one type of grout produced soft grout when excess water was used in the mixture. The soft grout versus water to solids ratio curve for plain grout with and without filler shows that when fillers are used in combination with HRWR admixtures to achieve workability at low water to solids ratio s, the sensitivity to formation of soft grout is increased substantially. Based on these findings, it can be concluded that using large percentages of filler material in combination with HRWR admixtures to achieve low water to solids ratio s increases the likeli hood of soft grout formation. It is recommended that additional filler material not be allowed in high performance PT grouts.

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17 CHAPTER 1 INTRODUCTION Post tensioned tendons are either bonded or unbonded Internal ly bonded post tensioned tendons are typically surrounded by corrugated polyethylene duct, but can also be smooth high density polyethylene (HDPE) duct. Pre packaged non shrink thixotropic grout is typically injected into the duct that surrounds the high str ength post tensioning steel. The grout provides a bond between the steel and the surrounding pre cast or cast in place segments. In addition to providing strain compatibility between the steel tendons and the surrounding concrete, the grout provides a corr osion resistant environment for the steel tendons. One example of a bonded tendon is a top slab longitudinal cantilever tendon that resists dead and construction loads during the balanced cantilever erection of a precast segmental box girder bridge superst ructure. External unbonded are installed after the segmental superstructure has been erected and will typically have the largest eccentricities. External unbonded continuity tendons are typically a nchored in diaphragms located in the pier. Continuity tendons are positioned above the center of gravity of the cross section near the pier segments and below it at mid span. During grout injection, t his large change in elevation head over considerable len gths is why continuity tendons are the most susceptible to segregation of the pre packaged grout components. External tendons are typically surrounded by a smooth, black HDPE duct, and can either be grouted or greased and sheathed. Unbonded tendons can als o be retrofit tendons like those that were installed in the Ringling Bridge In this case, the existing bridge was retrofitted with additional unbonded tendons after it was built. The webs of

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18 the segments were experiencing significant shear cracking, so th e extra deviated tendons were installed to carry dead and live load. This would then reduce the amount of shear the webs were exposed to. In 2011, two different instances of completely failed tendons were discovered in the Ringling Bridge, both due to corr osion of the steel from segregated unreacted putty grout. (Mario Paredes, June 17, 2013) A few of the issues encountered with the grouting of post tensioned tendons are voids, excessive bleed water, high chloride levels, and un reacted gelatinous grout Various field tests have been conducted in tandem with the inclined test tube to observe the fluid and hardened properties of both prepackaged PT grouts and plain grouts. The results from these tests are dis cussed in detail in this report. The prepackaged grouts were tested at the maximum specified water to solids ratio stated on the bag. They were also mixed using an additional 15% extra mixing water to observe how the fluid and hardened properties were aff ected by the increased water to solids ratio The plain grouts have been mixed using varying percentages of filler material and varying levels of HRWR admixture to achieve a set apparent viscosity level. The quantities of bleed and soft grout observed insi de of the inclined test tube were recorded and summarized in this report.

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19 CHAPTER 2 LITERATURE REVIEW Many issues can arise during and after the grouting of post tensioned tendons in bridges. Problems during grouting include relatively high pumping pressu res during injection of the grout into the tendons due to high grouting temperatures, or the highly thixotropic nature of PT grouts that can lead to premature setting times. These high pumping pressures can damage the progressive cavity pumps that are comm only used with colloidal grout mixing equipment, and can also damage the polyethylene ducts that are encased in the surrounding concrete. After the placement of the PT grout, problems such as bleed, voids, high chloride levels, and component segregation ca n occur. These are classified as problems because the purpose of the PT grout is to provide a basic environment and surround the high strength steel tendons, protecting them from corrosion. These problems are caused by the physical characteristics of the e nvironment the grout is placed in, as well as the components of the PT grouts and their relative proportions. In order to begin reviewing how the components of prepackaged PT grouts influence their fluid and hardened properties and how these properties eff ect the corrosion of high strength steel tendons, the problems encountered with grouting and how they lead to corrosion of the steel tendon must be investigated first. Cracking of the HDPE ducts, voids located inside of the grouted duct, bleed water, segre gation of the grout components, and high chloride levels can all lead to corrosion of the post tensioning steel tendons. High moisture levels can occur in the tendons from bleed water, water entering through cracks in the ducts, or water that is retained in segregated components of the

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20 PT grout that has not hydrated. Tensile capacities of the steel tendons are compromised when corrosion occurs. High moisture levels with negligible chloride levels can reduce the steel tensile capacity by 11.4% over a twelve month period (Trejo, Pillai, Hueste, Reinschmidt, & Gardoni, April 2009) Thus, assuming zero chloride penetration into the duct over the life span of the bridge, and zero chloride levels present in the components used to mix the grout, significantly rapid corrosion of the steel tendons can occur if there are high moisture content levels in the grout after placement Any condition that results in high moisture levels in the duct will result in rapid corrosion of the steel and p ossible failure of the steel tendons. Cracking of the HDPE ducts surrounding the steel tendons is one way for excessive moisture to penetrate into the duct and cause corrosion. Cracked ducts have been observed in bridges such as the Sunshine Skyway Bridge and the Mid Bay Bridge. It has been concluded that the grout played no role in the cracking of the HDPE ducts in the Mid Bay Bridge (Hartt & Venugopalan, April 2002) Some possible sources for cracking of the HDPE ducts are cyclic temperature changes and the inability of the duct to respond properly to these temperature variations, and also the way that the HDPE ducts interact with the hardened grout. Fatigue stress on the internal surface of the HDPE ducts due to temperature cycles can lead to cracking, and thus high moisture levels inside of the ducts (Suarez, Zhang, Hsuan, & Hartt, August 2006) Steel corrosion because of high chloride levels occurs when the chloride ions penetrate the alkaline film that immediately surrounds the steel, disrupting the basic environment in localized regions (Montemor, Simoes, & Ferreira, 2003) Chlorides can either penetrate into the ducts through cracks over the lifetime of the bridge or can be

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21 present in the PT grout components. The tensile capacity of the steel tendons can be reduced by as much as 27% over a 12 month period when high moisture levels coupled with high chloride levels are present (Trejo, Pillai Hueste, Reinschmidt, & Gardoni, April 2009) The FHWA has set a limit to how much water soluble chlorides may be present in cement of 0.15% by weight. Since it has been shown that elevated moisture levels in the ducts will result in reduced tensile capacity of the steel tendons due to corrosion, the mechanisms by which the grout components cause elevated moisture levels can be discussed. Pre packaged grout products that are used for post tensioning applications can have a range of potential issues th at can lead to elevated moisture contents inside of the ducts. If the bag weights are light, water to solids ratio s will be higher than specified by the manufacturer Additionally, pre packaged grouts can be affected by rapid hydration and aging of the cem entitious components if not stored and transported in a dry, cool environment. The components of the grout can also have a drastic effect on how much bleed water and voids are present in the duct after the grout has hardened, as well as how much segregatio n occurs during and after placement of the grout. Since June 1, 2013 the Post Tensioning Institution (PTI) Specification for Grouting of Post Tensioned Structures allowed for the use of Portland cement, mineral additives, chemical admixtures, aggregates, a nd water for grout ingredients. The addendum PTI M55.1 12 changed the specifications found in section 2.1 General Materials. The use of aggregates is now prohibited, unless used in Class D grouts. Additionally, mineral additives have been changed to supp lemental cementitious materials that are limited to

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22 fly ash, blast furnace slag, and undensified silica fume (Committee, PTI Specification for Grouting of Post Tensioned Structures, 2003) Type I/II Portland cement is a hydraulic cement that reacts with water and results in a hardened material that is impervious to water. There are many variations of Portland cement that range from Type I to Type V, with additional types that include air entraining agents for example Portland cem ent undergoes a hydration process where the chemical compound tricalcium aluminate (C 3 A) undergoes a rapid initial hydration. The hydration process can continue for an extended period of time after the initial cement hydration. This hydration process can s ometimes last for years (Corven & Moreton, May 2004) ASTM C150 specifies that Portland cement can be composed of up to 5% limestone filler material, and that certain physical properties must be verified in order to be qualifie d under ASTM C 150. These physical requirements are: setting time, soundness, fineness, consistency, compressive strength, heat of hydration, loss of ignition and specific gravity. Mineral additives such as fly ash, slag, and other supplemental cementitous materials are permitted as ingredients of grout per PTI grouting specifications Fly ash is a by product of the production of co al through a combustion process and reduces bleed and permeability of the grout Fly ash also reduces the amount of HRWR admixt ure needed to achieve desirable rheological properties in grout (Schokker, Koester, Breen, & Kreger, October 1999) Silica fume is an extremely fine material that is the by product of silicon manufacturing. It can be produced in three forms: slurry, undensified, and densified. Densified silica fume is produced by tumbling undensified silica fume in a silo which static ally charges the particles, causing them to clump together and increase the

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23 bulk density in the remaining material which makes for easier transportation methods. Undesified silica fume is used almost exclusively in prepackaged grout applications. Silica fu me can reduce bleed and permeability, while increasing the strength of the grout. The demand for dosage of HRWR admixtures is increased when using silica fume, and they increase the thixotropic nature of the grout (Schokker, Koester Breen, & Kreger, October 1999) Blast furnace slag that is type 120 is used in pre packaged PT grouts. The grades of blast furnace slag are categorized based on their activity index, which gives the mix designer an idea of how the compressive streng th of the material will be affected by the use of granulated ground blast furnace slag. The durability of the resulting cement is improved because there is an increased production of calcium silicate hydrate during the pozzolanic reaction between the blast furnace slag and water and cement (Cervantes & Roesler, July 2007) Clean potable water is used when mixing pre packaged PT grouts. The temperature of the water may sometimes need to be adjusted prior to mixing to better suit the ambient conditions present at the construction site. Water can be present in various places along the pathway of the grout such as the grout hoses, inside of the ducts, and inside of the grout pump that is used to place the fluid grout. Excess water ca n mix with the grout that is being injected, which is why it is recommended by the FHWA Grouting Manual to discharge at least 2 gallons of consistent grout through the exit valves before grouting can be terminated (Corven & Moreton, May 2004) Excess mixing water is one way moisture content levels are increased in the ducts, which will result in corrosion of the steel tendons.

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24 Chemical admixtures can serve multiple roles in PT grouts. They can help with pumpability by reducing the viscosity of the grout, while also helping with controlling the time it takes for the grout to set. Reduction in water is another advantage to using chemical admixtures, while corrosion control, volume control, and air entrainment are also benefits to using chemical admixtures in PT grouts. High ra nge water reducing (HRWR) admixtures are used to achieve low water to solids ratio s in pre packaged grouts. They can be either polycarboxylate, melamine sulfonate, or naphthalene sulfano based. Polycarboxylate based HRWR admixtures are used in post tensioning applications. Experimental data has shown that the yield stress and plastic viscosity for a cement paste with a polycarboxylate based HRWR admixture decreases as you increase the HRWR dosage up until the s aturation dosage. High temperatures can have an interesting effect on cement pastes with polycarboxylate based HRWR admixtures. An increase in temperature will amplify the thixotropic nature of the cement paste that has polycarboxylate based HRWR admixture s (Martini & Nehdi, August 2009) HRWR admixtures do have their drawbacks. Bleed has been shown to increase when HRWR admixtures are used in PT grouts (Committee, PTI Specification for Grouting of Post Tensi oned Structures, 2003) Additionally, HRWR have been shown to increase the time in which it takes for the grout to set, which can lead to additional bleeding. have previously been allowed to be used in prepackaged P T grouts before the PTI Specifications were changed. Filler material acts as a cost efficient way to minimize the quantity of Portland cement used per bag. Furthermore, inert fillers such as calcium carbonate used in Portland cement paste will decrease the temperature sensitivity of the cement paste. (Jue, 2012) This could make

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25 filler material a desirable component in PT grouts for hot weather injection. A common misconception about calcium carbonate is that it is completely in ert. It has been shown that the calcium carbonate when used as a filler up to 5% does react to some degree with the tri calcium aluminate that occurs when Portland cement and water react to form monocarboaluminate (Hawkins, Tennis, & Detwiler, 2003) The filler material calcium carbonate has been shown to decrease the initial and final set time when substituted into Portland cement mixes (El Didamony, Salem, Gabr, & Mohamed, 1994) Previous research has been conducted at the FDOT State Materials Office by the University of Florida to investigate prepackaged PT grouts and how they behave under various field conditions. Using the inclined test tube configuration, field conditions such as pressurized injection at 55 psi, high temperature injection, duct filled with strand, pressurized set at 60 psi, strand at the top of the duct, 2 gallons of water in the hose, 2 gallons of water in the duct, 15% addi tional water to solids ratio, maximum water to solids ratio, and constricted regions in the duct. The only testing that resulted in soft grout was under conditions that used excessive water, such as 2 gallons of water in the hose and 15% additional water t o solids ratio. There was a single instance of soft grout formation when the PT grout that did produce soft grout when mixed with excess water was pumped into a constricted duct. (Hamilton, 2013)

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26 CHAPTER 3 OBJECTIVE AND APPRO ACH The objective of this research was to determine the effect of filler material s such as calcium carbonate on the formation of soft grout at various water to cement ratios and percentages of filler additions Additionally, the results from the plain cem ent and filler tests were compared to the results from tests conducted on prepackaged high performance PT grouts. Current specifications do not limit the quantity of non reactive fillers that can be used in PT grout. Based on the results of testing on pr epackaged grouts, it is hypothesized that the use of limestone fillers can precipitate or exacerbate the formation and quantity of soft grout. ASTM C150 allows 5% limestone filler by mass (ASTM C150 12 Standard Specification for Por tland Cement, 2012) Furthermore, prepackaged high performance post tensioning grouts will also contain limestone fillers in unknown proportions. A modified version of the Euronorm inclined tube test (EN 445 Grout for pestres sing tendons Test methods, 2007) was used to evaluate the presence and quantity of soft grout produced with mixtures containing varying quantities of filler material. A full scale colloidal grout mixing plant was used to mix and inject the grout int o inclined tubes. For the plain grouts, the percentage of filler and water to cement ratio were varied, while the water to solids ratio was varied for the pre packaged high performance PT grouts. Use of a high range water reducer (HRWR) admixture on the plain grout mixtures was necessary to achieve the low water to solids ratio s comparable to those found in typical prepackaged PT grouts and still maintain a constant viscosity Rheological measurements were conducted for each inclined tests to ensure cons istency in the apparent viscosity (250 mPa*sec) among the varying mixtures. This

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27 value is similar to the initial apparent viscosities measured on commercially available prepackaged PT grouts.

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28 CHAPTER 4 MATERIALS Tests on both plain and prepackaged grouts included preparing a grout mixture using a full scale grout plant. The plain grout mixtures were formulated from water, Portland cement, ground limestone, and high range water reducer (HRWR). Prepackaged grouts were also tested; constituent materials and their proportions, however, were unknown due to the proprietary nature of the products. This chapter describes the materials that were used to create these grout mixtures. Plain Grout Plain grout mixtures con t ained Portland cement, ground limestone filler water, and HRWR Three limestone f iller quantities were selected at 0%, 35%, and 45% replacement by weight of cement These percentages of filler material were chosen to investigate the behavior of plain gr outs with and without large proportions of filler material. Table 4 1 below shows the testing identification codes for tests conducted at various water to cement ratios and filler percentages. Portland Cement The filler material in combination with ASTM C1 50 type I/II Portland cement was mixed at water to cement ratios ranging from 0.3 0 to 0.825. The Portland cement was obtained from Florida Rock in Newberry Florida. Figure 4 1 below shows three total plots of the particle size distribution for the type I/ II Portland cement that was used in these experiments. Three total particle size analyses were conducted on the Type I/II Portland cement using a laser diffraction particle size analysis machine with the following mean

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29 and standard deviation values: [15.74 (m), 14.26 (m)], [16.1 (m), 17.14 (m)], [14.83 (m), 10.59 (m)]. Filler Material P ulverized limestone (calcium carbonate) was obtained at a local farm supply store for use as filler L aser diffraction particle size analysis results are given in Figure 4 2 Three total particle size analyses were conducted, with the following mean and standard deviation values: [30.03 (m), 39.99 (m)], [6.70 (m), 34.19 (m)], [29.89 (m), 39.19 (m)]. Table 4 2 below shows the resu lts from PSA tests conducted on the prepackaged PT grouts. Based on Table 4 2, p repackaged PT grout mean sizes range from 2 5 (m) to 55 (m) This variation in mean size is either because of coarser materials being used or because of changes in the powder due to pre hydration of the cementitious material. Only speculations can be made because the constituents of each prepackaged PT grout is proprietary knowledge known only by the manufacturer. Furthermore, the mean particle sizes from the filler material an d Portland cement appear to be similar in size to the prepackaged PT grouts. High Range Water Reducing Admixtures Adva s used to control the viscosity of the grout. Dosage of the HRWR was adjusted with each mixture to maintain a maximum viscosit y of 250 mPa*sec, which is a practical value with respect to the ability to pump the grout to the target at high temperatures for extended periods of time and is t ypical of that found in pre packaged post tensioning grouts. Specific HRWR quantities are discussed further in Chapter 8

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30 Prepackaged PT Grouts Inclined tube tests were conducted on six commercially available prepackaged P T grouts The results from these tests were compared in detail to the results obtained from the tests on plain grout.

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31 Table 4 1. Summary of Plain Grout Tes t ing ID Description CXX YY XX = water to cement ratio YY = percentage of filler Example: C55 45 ( water to cement ratio = 0.55, percentage of filler = 0.45) Table 4 2. Summary of PT grout PSA Grout ID Mean particle size ( m) PT1 4 25.00 PT2 4 30.55 PT3 3 42.20 PT4 6 45.20 PT5 1 32.67 PT6 1 51.37 Figure 4 1 Particle size distribution for Portland cement

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32 Figure 4 2 Particle size distribution for calcium carbonate

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33 CHAPTER 5 MIXING EQUIPMENT AND PROCEDURES This section describes the equipment that was used to mix and inject both prepackaged PT grouts and plain grouts into the inclined test tube. Furthermore, the mixing procedures used for both plain grout mixtures and prepackaged PT grout mixtures are described in detail. Colloidal Grout Plant Figure 5 1 below shows the Chemgrout CG600 colloidal grout mixi ng plant that was used for these experiments. PT Grout Mixing Procedure The following procedure was used to mix the PT grouts using the CG600 colloidal grout mixer. 1. Add water to mixing basin and turn on colloidal mixer and agitator paddle. See Figure 5 2 below. 2. Add one bag of grout at a time. Add grout over a period of 20 30 seconds per bag. See Figure 5 3 below. 3. Continue running colloidal mixer and agitator paddle for 30 seconds after adding last bag of grout. 4. Turn off entire machine and scrape any powde r caked onto the inside of the mixing tank walls back into the grout. See Figure 5 4 below. 5. Turn on the colloidal and continue mixing for 2 minutes 6. Record the temperature of the grout while it is in the mixing basin. 7. Transfer the grout to the agitation ta nk and start the paddle in the agitation tank. See Figure 5 5 below. 8. Begin pumping grout after as quickly as possible. See Figure 5 6 below.

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34 Plain Grout Mixing Procedure The following procedure was used to mix the plain grouts using the electric/hydraulic colloidal grout mixer. 1. Add water to mixing basin and turn on colloidal mixer and agitator paddle. 2. Add one bag of Portland cement at a time. Add Portland cement over a period of 40 60 seconds per 94 pound bag 3. After adding all of the Portland cement, add HRWR admixture then the first 50 pound bag of calcium carbonate over a period of 20 30 seconds per bag. 4. Repeat step 3 until all bags of calcium carbonate are added. Check the flow cone of the plain grout when it is still in the mixer. If nee ded, add additional HRWR admixture to attain the desired grout fluidity. 5. Continue with step 3 from PT Grout Mixing Procedure

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35 Figure 5 1 Chemgrout CG600 E/H 3CL6 Progressive cavity pum p (Photo courtesy of the author) Figure 5 2 Add water to mix ing basin (Photo courtesy of the author)

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36 Figure 5 3 Add one bag of grout at a time (Photo courtesy of the author) Figure 5 4 Scrape the inside of the mixing basin (Photo courtesy of the author)

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37 Figure 5 5 Transfer the grout to the agitation tank (Photo courtesy of the author) Figure 5 6 Pump grout to target (Photo courtesy of the author)

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38 CHAPTER 6 TEST METHODS The tests outlined in this chapter were conducted each time the grout was mixed and injected into the inclined tube. They consisted of tests on both fluid and hardened properties. The modified flow cone, unit weight, mud balance, Schupack, and apparent v iscosity tests were conducted on the fluid grout immediately following mixing. After injection, visual observations were made on the tube to detect bleed water at the top of the incline. After 24 hours, the tube was then dissected and inspected for soft grout. Finally, samples of grout were taken during dissection and measured for moisture content. The following sections describe the details of these test procedures. Inclined Bleed test A modification of the Euronorm EN445 2007 (E N 445 Grout for pestressing tendons Test methods, 2007) was used to simulate grout bleed and segregation under field conditions. The test was conducted by injecting grout into a 15 ft long x 3 in. diameter transparent PVC pipe filled with twelve 0.6 in. diameter post tensioning strands. The strand was cut to 14.5 ft to leave a void where accurate measurements of any segregated soft grout can be obtained. The grout was mixed in the mixing basin using the colloidal, and pumped into the duct using the progressive cavity pump. Bleed and soft grout measurements and sampling t ook place 24 hours after injection. Figure 6 1 shows a schematic of the inclined bleed duct configuration. Fig ure 6 2 shows a photograph of the actual inclined bleed ducts used for testing. The procedure for mixing and injecting grout for the inclined bleed test is as follows: 1. Mix grout in colloidal grout plant according to mix procedure.

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39 2. Transfer grout to a gitation tank and start agitator paddle. 3. approximately 2 gallons and run the following tests: apparent viscosity, flow cone, mud balance, unit weight and Schupack pressure bleed t est. 4. Attach grout hose to duct. 5. Inject grout into duct over a period of approximately 1 minute. Discharge approximately 2 gallons out of the top of the duct. Record the following during injection: inlet and pump pressure, fill time, discharge tempera ture. 6. Run the following tests on the 2 gallons of grout discharged from the top of the duct: flow cone, mud balance, unit weight and Schupack pressure bleed test (ASTM C1741 12 Standard Method for Bleed Stability of Cementitious Post tensioning Tendon Grout, 2012) Modified Flow Cone The modified ASTM C939 Flow Cone test was used to measure the fluidity of the grout while it was in fluid form. The modified flow cone test was developed for testing thixotropic grouts. The flow cone is filled completely, the plug at the bottom is pulled, and the time it takes to fill a 1000 mL beaker is recorded. Flow cone times should be between 5 seconds and 30 seconds for thixotropic PT grouts. The modified flow cone test was conducted before and after injecting all grouts, and was run before final additions of HRWR admixtures during plain grout testing. Figure 6 3 and Figure 6 4 show a schematic and photo of the modified flow cone, respectively. Unit Weight The density or unit weight was measu red using a cup with a known volume, and weighing the amount of grout needed to fill the cup completely. The inside volume of the cup was known to be 0.0141 ft 3 The grout was poured into the unit weight cup after zeroing the scale with the unit weight cup and glass top. Then the excess grout was wiped off from the outside of the cup, and the configuration was weighed. The unit

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40 weight was simply the measured weight divided by the known volume. Figure 6 5 below shows a photo of the empty unit weight cup. Mud Balance grout in fluid form. This test uses a beaker attached to a rod with a moveable counter balance on the opposite end of the beaker that is balanced on a fulcrum point. There is a level above the fulcrum point that allows the user to measure the density of the grout. The mud balance test was conducted on all grout before and after injection. Figure 6 6 below show a picture of the mud balance being used during a grouting operation. Pressure Bleed Test The Pressure Bleed Test (ASTM C1741 12 Standard Method for Bleed Stability of Cementitious Post tensioning Tendon Grout, 2012) was used to compare with data obtained from bleed measurements from the full scale bleed test. The Schupack test uses air pressure and a fabric filter inside of a stainless steel cylinder to measure a grouts susceptibility to bleeding. Figure 6 7 below sho ws a photo of the Schupack test. Figure 6 8 shows the various components that make up the Schupack pressure bleed test. Figure 6 8 below shows the parts used to perform a pressurized Schupack bleed test. From left to right, the parts are: cylinder top cap, specimen cylinder, cylinder bottom bleed tube, metal screen, fabric filter, plastic filter ring. From Figure 6 7 below it can be seen that pressurized air is pumped through the top of the c ylinder while the sample is inside of the cylinder for a finite amount of time. The scree n fabric filter, and plastic ring are all located under the sample, and above the bleed tube. The bleed water is collected in a beaker, and the volume is recorded.

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41 Ap parent Viscosity Test The apparent viscosity of the grout was measured before and after injection using a dynamic shear rheometer (DSR). Figure 6 9 below shows a photo of the DSR with the doors open. A helical ribbon geometry and cup were used to test the grout. Figure 6 10 below shows the cup and ribbon next to each other. The DSR works by rotating the ribbon, which is attached to a threaded rod, using a frictionless air bearing. The rheometer measures the torque that results when the ribbon is submerged i nto fluid grout. The torque is then converted to shear stress based on a factor that must be determined by testing a standard reference material to calibrate the machine. The shear strain is determined by multiplying the angular velocity by a known shear s train factor that can be obtained from the manufacturer of the cup and ribbon. The apparent viscosity is then calculated by dividing the measured shear stress values by the calculated shear strain. A schematic of both the helical ribbon geometry and the c up that the ribbon is lowered into that holds the fluid grout can be seen below in Figure 6 11 and Figure 6 12 respectively. Bleed W ater M easurement The traditional inclined bleed test calls for bleed measurements immediately after injecting the inclined tube at specific time intervals, but for these tests bleed measurements were conducted after the grout had been allowed to harden for 24 hours. This is because previous inclined bleed tests that were conducted before these tests resulted in no bleed immedi ately following grout injection. The ducts were removed from the inclined stand, and the top exit valve was removed by unscrewing it with a set of pliers. The duct was then carefully tilted so that any bleed water would pour into a large

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42 graduated cylinder that was placed under the exit. All bleed water was poured into the graduated cylinder, and the final volume was recorded. Soft G rout I dentification and M easurement At approximately 24 hours after injection, the region near the exit of the duct was cut op en and inspected for soft grout. Soft grout was defined as grout that could be molded or deformed by hand and that appeared to have excessive moisture content. If bleed water was present, then that was measured separately. A flathead screwdriver was use d to gently probe and scrape the grout in the exit region until all soft grout was removed. Soft grout was collected and weighed. Figure 6 13 shows the exit region of one of the inclined tubes that PT4 6 was injected into at 15% excess mixing water. Mois ture C ontent Moisture content samples were gathered from the PT duct 24 hours after grout injection. Figure 6 14 shows the locations along the inclined test tube from which the moisture content samples were taken. These locations were selected to show the variation of moisture content along the length of the duct. The moisture content values were determined by measuring the moist weight of the grout, and then the grout samples were placed into an oven for 24 hours. The samples were then weighed, and the mo isture content was calculated. Figure 6 15 Figure 6 16 and Figure 6 17 show the moisture content scale, samples, and samples inside of an oven, respectively. Figure 6 18 below shows the hand held band saw used to cut the incline tube for sampling the ex it region. After using a cut off wheel to remove the PVC duct, a jack hammer was used to gather a sample the hardened grout from the top and bottom of the cross section as shown in Figure 6 19 Although the volume of the samples varied, typically a suffic ient quantity of grout to cover the bottom of the pan was gathered.

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43 Figure 6 1 Inclined test tube schematic Figure 6 2 Inclined test tube picture (Photo courtesy of the author)

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44 Figure 6 3 ASTM C939 Modified Flow Cone schematic Figure 6 4 ASTM C939 Modified Flow Cone test (Photo courtesy of the author)

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45 Figure 6 5 Unit weight cup and glass plate (Photo courtesy of the author) Figure 6 6 (Photo courtesy of the author)

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46 Figure 6 7 Schupack Pressure Bleed Test (Photo courtesy of the author) Figure 6 8 Schupack pressure bleed test components (Photo courtesy of the author)

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47 Figure 6 9 Dynamic Shear Rheometer (Photo courtesy of the aut hor) Figure 6 10 Helical ribbon and cup (Photo courtesy of the author)

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48 Figure 6 11 Helical Ribbon Schematic

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49 Figure 6 12 DSR Cup Schematic

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50 Figure 6 13 PT4 6 Soft Grout (Photo courtesy of the author) Figure 6 14 Inclined Test Tube Sampling Locations

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51 Figure 6 15 Moisture content scale (Photo courtesy of the author) Figure 6 16 Moisture content samples (Photo courtesy of the author)

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52 Figure 6 17 Moisture content samples inside oven (Photo courtesy of the author) Figure 6 18 Band saw used during dissection (Photo courtesy of the author)

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53 Figure 6 19 Jack hammer used during dissection (Photo courtesy of the author)

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54 CHAPTER 7 RESULTS AND DISCUSSION Apparent V iscosity C ontrol The plain grout mixtures were adjusted so that the initial apparent viscosity was at or below 250 mPa*seconds for all of the plain grout tests. This was accomplished by adjusting the HRWR admixture dosage using the flow cone values and visual observation of the mixture in the mixing tank during mixing Measurements of apparent viscosity were recorded after mixing. Figure 7 1 shows the HRWR admi xture quantity used for each mix at different percentages of filler material versus the water to cement ratio The horizontal dashed line in the figure indicates the absolute limit for the volume of HRWR admixtures. Adva cast specifies that a maximum of 650mL/100kg of HRWR admixture per weight of cement material should not be exceeded. For each test that w as conducted, two 94 pound bags of cement were used. This correspond ed to a maximum of 550 mL of HRWR admixture that should not be exceeded. Section 2.4.1 in the PTI Specification for Grouting of Post Tensioned Structures allows 3000 mL/100 kg of HRWR admixture per weight of cement material. This correspond ed to roughly 2500 mL of HRWR admixture for a test conducted with 186 pounds of Portland cement. Thus, the limit for the testing conducted for this report was set at 550 mL and the PTI specificatio ns. T he experiment conducted at 0 .35 water to cement ratio and 35% filler (C35 35) required an amount of HRWR admixture that exceeded the limitations stated by the manufacturer Adva cast. This outcome was not known prior to running the test. For this reason, the test at 0.35 water to ceme nt ratio could not be conducted at 45% filler (C35

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55 45) because the target apparent viscosity could not be achieved without exceeding the recommended limit for HRWR admixtures. Figure 7 2 shows the resulting apparent viscosity levels for all tests conducted at a range of water to cement levels and percentage of filler material. Although viscosity varied significantly between mixtures, the figure demonstrates that the apparent viscosities were all controlled so that they did not exceed 250 mPa*sec. Figure 7 3 shows the resulting initial flow cone efflux times from all tests conducted at a range of water to cement levels and percentage of filler material. Figure 7 3 confirms that at a given water to cement ratio, increasing the percentage of filler will incre ase the modified flow cone efflux time. This is expected because for any given water to cement ratio, the same amount of water was used to mix the grout, so increasing the percentage of filler only adds solids to the mixture, which would intuitively yield a larger flow cone value. Take for example a mixture that consists of water only. If calcium carbonate is added to the mixture, the apparent viscosity should increase. The use of the HRWR admixture also affects the fluid characteristics measured by the mod ified flow cone test, but the increase in the weight of solids appears to overcome these affects. Representative T est R esults The following is a representative sample of plain grout and prepackaged grout and their respective results. The results from the representative set of data for the pre packaged high performance post tensioning grout testing can be found in Table 7 1. The results from the representative set of data for the plain grout testing can be found in Table 7 2.

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56 Soft G rout Characterization and M easurement The consistency of the soft grout obtained from different tests was not t he same. For the plain grout mixtures that produced soft grout, the consistency, moisture content, color, and quantity typically varied substantially. The soft grout foun d in PT4 6 mixtures with extra water was similar in color and consistency, but these characteristics were slightly different than the soft grout found in plain grout mixtures. Table 7 3 below shows a summary of all soft grout samples obtained. Soft grout could be placed in three groups based on their characteristics. For the prepackaged PT grout PT4 6, which occupies the last three rows in Table 7 3 below there was one type of soft grout which had a dark gray color and a mud like consistency with a moistu re content over 72%. The plain grouts exhibited two distinctly different types of soft grout. The first was the lighter colored firm clay like wafer that was observed when low water to cement ratios were used and high levels of HRWR admixtures were used. T he second was the darker colored soft grout that had a similar consistency to the soft grout obtained from the PT4 6 mixtures. Figure 7 4 below shows this type of soft grout being squeezed between fingers. Based on Figure 7 4 below it can be seen that thi s particular type of soft grout does indeed resemble wet clay when squeezed between ones fingers. Figure 7 5 below shows the soft grout being sampled from a test conducted on PT4 6 which has more of a wet consistency relative to all other soft grout sample s that were obtained during these tests. Figure 7 5 shows that the soft grout obtained from PT4 6 had a similar consistency of wet mud. Figure 7 6 below shows another PT4 6 inclined test exit region that had soft grout. Figure 7 6 shows a slightly diffe rent consistency of soft grout found

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57 when conducting the sensitivity study on PT4 6. This soft grout had a consistency that was similar to wet clay, instead of wet mud. Figure 7 7 shows the segregated soft grout material being sampled from the exit region of the duct injected with C675 45. T he soft grout obtained from mixing Portland cement and calcium carbonate filler has a similar consistency as the soft grout shown in Figure 7 6 The coloration of the two different soft grout samples was different, wit h C675 45 soft grout being lighter than PT4 6 soft grout. Figure 7 8 below shows the soft grout material that was obtained from mixing C35 0 Portland cement and no additional filler material. Figure 7 8 shows a different consistency of soft grout than tha t found in Figure 7 7 This soft grout had a consistency similar to a moist cake like material At first sight, it appeared to be a dry cake but when squeezed together it deformed and revealed a soft moist material. Figure 7 9 shows the wet clay like mate rial that is left over after the moist wafer has been squeezed between ones fingers. As you can see from Figure 7 9 below the soft grout was initially a wafer like material, but after shearing it between two surfaces such as fingers, the wafer compressed into a wet clay like material. The moisture content for this soft grout was typically above 60% moisture. Figure 7 10 shows hardened grout for the test C35 35 which had a moisture content of approximately 30% with no gelatinous soft grout or equator line separating the soft grout from the hardened grout. Sampling of soft grout from inclined specimens results in some variability due to the interference of the prestressing strand and the transitional nature of the grout

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58 properties. Additionally, at extremely high water to cement ratios, the bleed water occupies a large portion of the inclined tube near the exit ( Figure 7 11) Thus, the free surface of the soft grout occupies the same region of tube that the PT strands occupy. Conseq uently, extracting all soft grout from the sample is not possible in some cases, which may lead to variability in the results The filler material segregate d from the more dense cementitious material, and was conveyed to the top of the inclined tube throu gh a small canal shown in Figure 7 1 2 below. This canal, which was located at the top of the cross section of the duct, was a clear indication that segregation had occurred ( Figure 7 1 3 ) Soft grout was typically found near the exit region, and sometimes o ccup ied the top of the cross section along the length of the duct where the segregation canal wa s located. Figure 7 1 4 below shows soft grout for the inclined test on PT35 55 which extended roughly one foot down the segregation canal. Figure 7 1 5 shows the cement and the soft grout. Figure 7 1 6 shows the equator line for observed when dissecting an inclined test tube injected with PT4 6 mixed at 15% excess mixing water. Figure 7 1 5 and Figure 7 1 6 both show the line between the hardened grout and the soft gelatinous grout. The equator line for the plain grout shown in Figure 7 1 5 is closer to the bottom of the cross section because there is a larger void present. The equator line for PT4 6 in Figure 7 1 6 is higher in the cross section than the equator line shown in Figure 7 1 5 Note that the arrow in Figure 7 1 6 points slightly below the pronounced line above which is the free surface of the soft grout. This is because the soft clay like

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59 grout occupied the region of the duct above where the arrow is pointing, and the hardened cement occupied the rest. Additional observations can be made on the appearance of the grout in Figure 7 1 5 and Figure 7 1 6 PT4 6 in Figure 7 1 6 has a thin layer of black material which has also segregated and ended up at the free surface of the grout. This material is most likely silica fume. The soft grout found when PT4 6 was used had a grey coloration. This is different from the soft grout found in the plain grout mixes, which w as typically lighter in color. Variation with F iller Figure 7 1 7 and Figure 7 1 8 both show the effect of water to solids ratio on the production of soft grout. The soft grout quantities shown in Figure 7 1 8 are plotted versus water to solids ratio This indicates that for a given water to solids ratio the same amount of powder material by weight was used. Based on the trends from the different filler material displayed in Figure 7 1 8 it can be concluded that the quantit y of soft grout increase d when add itional filler material was used. Additionally, a t lower water to solids ratio was used to achieve zero soft grout in the inclined test tube for mixes with increasing percentages of filler material. It should be noted that the dip in the curve near the 0.3 5 water to solids ratio for 35% filler and 45% filler observed in Figure 7 18 is most likely due to bleed water occupying the same cross section as the PT strands, making it difficult to sample all of the soft grout that coated the strands. Figure 7 11 sho ws a picture of a ducts that had moist grout that surrounded the PT strands after the bleed water was sampled.

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60 Moisture content Plain Grout Figure 7 1 9 Figure 7 20 and Figure 7 2 1 show moisture contents along the length of the duct for varying water to cement ratios with 0%, 35%, and 45% filler, respectively. Several trends are noteworthy. First, m oisture content below the discharge generally ranged from a low of 15% to a high of 30%. As would be expected, the increase in moisture content followed the increase in w/c. Also, moisture content increased gradually along the length of the duct up to the discharge poin t where drastic increases in moisture content were measured. Since the HRWR admixture was used in conjunction with water to limit the initial apparent viscosity for most of the tests, all but three of the below tests resulted in soft grout near the exit r egion. The relatively high moisture contents near the exit region are a clear indication of this. The test conducted at 0.3 water to cement ratio and zero additional filler material displayed in Figure 7 1 9 has moisture contents that are consistently belo w 20% and resulted in zero soft grout. This test required the most HRWR admixture to limit the initial apparent viscosity. This is clear indication that with low enough water to cement ratios, large amounts of HRWR admixtures can be used to achieve desirab le fluidity characteristics without resulting in segregation of the Portland cement and filler material. Prepackaged PT grout Figure 7 2 2 shows the moisture content along the length of the duct for pre packaged PT grouts mixed at their maximum specified w ater to solids ratio The figure indicates that the P T grouts behaved satisfactorily with no soft grout or bleed water present along the length of the duct. This is what one would hope to expect from a PT

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61 grout injected into a full scale inclined duct with the maximum amount of mixing water specified by the manufacturer. Figure 7-23 shows the moisture contents along the length of the duct for all high performance pre-packaged PT grouts mixed at 15 percent extra mixing water. Based on Figure 7-23 below, all of the PT grouts behaved satisfactorily, with the exception of PT 2-4, and PT4-6. The moisture content at the free surface of the grout near the exit valve for PT 2PT 4-6 mixed at 15 percent extra water resulted in soft grout near the exit valve. PT 46 was the only preon the high performance grouts. Bleed Figure 7-24 and Figure 7-25 compare the bleed measured with the inclined test and the pressure bleed stability (ASTM C1741-12 Standard Method for Bleed Stability of Cementitious Post-tensioning Tendon Grout, 2012) Figure 7-24a shows that increasing the percentage of filler decreases the amount of bleed water at higher water to cement ratios. However, at lower water to cement ratios such as 0.45, there is no bleed water present for any of the percentages of filler. PT grouts are typically mixed at water to cement ratios of less than 0.45, so the use of filler material for reducing bleed is not justifiable based on these findings. Furthermore, if fillers are going to be used, then something must be done to prevent segregation of the Portland cement from the filler material. It might be possible to use retarding agents or viscosity modifying admixtures to reduce bleed and prevent soft grout. Figure 7-24b shows that increasing the percentage of filler at any water to cement ratio will decrease the bleed. PT grout bleed is typically addressed using small

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62 scale laboratory tests like the Schupack pressure bleed test to determine if the prepackaged product will have excessive bleed characteristics. Based on the results from Figure 7 2 4 the pressure bleed te st detects bleed susceptibility over all ranges of filler content and w/c Inclined bleed, however, is not detected at lower w/c ratios, which is also the levels at which the PT grouts are mixed. Figure 7 2 5 a shows that as the percentage of filler materi al is increased, a lower water to solids ratio was necessary to achieve zero bleed in the inclined duct. Figure 7 2 5 b shows practically no difference between the mixes conducted at 35% and 45% filler Results from mixtures with and without fillers, howeve r, indicate significant differences in bleed HRWR and S egregation Figure 7 2 6 shows that the HRWR admixture is increasing the amount of segregation The plot indicates that the moisture content is relatively consistent with the exception of the top of th e inclined where the mixture containing HRWR has nearly twice the moisture content as that of the mixture without HRWR. Given that this mixture contained no added filler, it is possible that the small percentage of the inert filler material that is present in the Portland cement was segregated because of the use of the HRWR admixture. Figure 7 2 7 and Figure 7 2 8 show the moisture content with and without HRWR admixture for 35% filler tested at w/c = 0.675, and 45% filler tested at w/c= 0.825, respectively. The figures indicate that t he moisture content along the length of the duct is consistently higher when no HRWR admixture is used, except at the exit of the inclined tube where they are consistentl y lower. One explanation for this behavior is that HRWR use caused filler material segregat ion from the cementitious material due to

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63 excessive bleeding which result ed in normal hardened grout along the length of the duct up until the exit. When no high range water reducing admixtures are used, the filler material is more evenly dispersed along the length of the duct, resulting in higher moisture contents because the filler is holding water rather than reacting with it. Figure 7 2 9 Figure 7 30 and Figu re 7 3 1 show the bleed, soft grout, and apparent viscosity readings from multiple experiments, respectively. Based on the comparison between multiple tests conducted at the same water to cement ratios and percentages of filler material, the use of HRWR adm ixtures increased the grout bleed and soft grout quantities observed in the inclined tube. The HRWR admixture also decreases the apparent viscosity of the grout in fluid form substantially. One advantageous approach to analyzing the results from the plain grout tests is to plot the different test results against the ratio of the volume of water used in the mix to the volume of the HRWR admixture used, which is a dimensionless parameter. Figure 7 3 2 Figure 7 3 3 and Figure 7 3 4 all display the maximum mois ture content, bleed water, and soft grout plotted against this dimensionless parameter, respectively. Figure 7 3 2 reveals an interesting trend in the moisture content results. All three sets of data with different percentages of filler material appear to converge to roughly 60% moisture content at high water/HRWR ratios. Additionally, at low water/HRWR ratios the maximum moisture contents seem to increase as the percentage of filler material is increased. Figure 7 3 3 and Figure 7 3 4 also show some interes ting grout behavior when plotted against the dimensionless parameter. The plots reveal that for a given

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64 water/HRWR ratio, increasing the percentage of filler will increase the amount of bleed and soft grout formation.

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65 Table 7-1. Representative Sample: Prepackaged PT grout experiment 34 PT PT4 6 dry powder wt (lbs.) 202 powder temp (F) 73.8 water weight (lbs.) 62.1 water temp. (F) 76.2 target water to solids ratio 0.311 theoretical water to solids ratio 0.307 mix time (min.) 8.00 temp. measured from mixer (F) 90.5 temperature at hose exit (F) 71.8 flow cone (sec.) 5.33 mud balance (pcf) 128 unit wt (pcf) 128 apparent viscosity (mPa*sec.) 100 temperature for DSR readings (F) 71.8 Schupck bleed (mL) 0 flow cone (sec.) 5.42 mud balance (pcf) 128 unit wt (pcf) 129 apparent viscosity (mPa*sec.) 103 temperature for DSR readings (F) 84.2 Schupck bleed (mL) 0 pump outlet pressure (psi) 40 duct inlet pressure (psi) 40 discharge at duct exit valve (gal) 2 duct fill time (sec.) 58 weight of soft grout (g) 159 moisture content at bottom 16.00 moisture content at exit 72.70

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66 Table 7-2. Representative Sample: Plain grout Field variable Value experiment 76 PT PC30 0 dry powder wt (lbs.) 183.94 powder temp (F) 70.3 water weight (lbs.) 55.18 water temp. (F) 77.6 target water to solids ratio 0.3 theoretical w/s 0.299 theoretical w/c 0.299 HRWR admixture (mL) 350 mix time (min.) 10 temp. measured from mixer (F) 91.3 temp. at hose exit (F) 82.8 flow cone (sec.) 7.95 mud balance (pcf) 128 unit wt (pcf) 131.06 apparent viscosity (mPa*sec.) 237 temp. for DSR readings (F) 82.8 Schupck bleed (mL) 4.66 flow cone (sec.) 8.98 mud balance (pcf) 126 unit wt (pcf) 130.78 apparent viscosity (mPa*sec.) 224.3 temperature for DSR readings (F) 82.9 Schupck bleed (mL) 5.71 pump outlet pressure (psi) 40 duct inlet pressure (psi) 40 discharge at duct exit valve (gal) 2 duct fill time (sec.) 63 weight of soft grout (g) 0 moisture content at bottom 14.51 moisture content at exit 16.27

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67 Table 7-3. Soft grout summary Grout type Color Consistency/ Description Quantity (g) Moisture Content C35 0 Light gray Firm moist clay wafer 23.8 64.5 C45 0 Light gray Firm moist clay wafer 18.9 56.3 C675 0 Light gray Moist/ soft clay 35.1 39.1 C825 0 Light gray Moist/ soft clay 71 67.3 C35 45 Light gray Firm moist clay wafer 115 67.7 C35 55 Tan Moist/ soft clay 69 66.4 C35 675 Light gray Moist/ soft clay 97.8 62.5 C35 825 Light gray Moist/ soft clay 120 58.8 C45 45 Light gray Firm moist clay wafer 49 74.2 C45 55 Light gray Moist/soft clay 123.2 76.2 C45 675 Tan Moist/soft clay 106.2 61.4 PT4 6 Light gray Moist/ soft clay 160 57.5 PT4 6 Dark gray Moist/soft clay 55.6 72.7 PT4 6 Dark gray Moist/ wet mud 159.2 72.7 PT4 6 Dark gray Moist/soft clay 79.4 75.7

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68 Figure 7-1. HRWR admixture dosage Figure 7-2. Resulting initial viscosities

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69 Figure 7-3. Resulting initial flow cones

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70 Figure 7-4. Moist clay like soft grout with darker coloration (Photo courtesy of the author)

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71 Figure 7-5. PT4-6 Soft Grout (Photo courtesy of the author) Figure 7-6. PT4-6 Soft Grout (Photo courtesy of the author) Figure 7-7. C675-45 Soft Grout (Photo courtesy of the author)

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72 Figure 7-8. C35-0 Soft Grout (Photo courtesy of the author) Figure 7-9. C35-0 Soft grout being squeezed together (Photo courtesy of the author)

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73 Figure 710. C35-35 Hardened Grout (Photo courtesy of the author) Figure 7-11. C67535 Large void due to bleed water (Photo courtesy of the author)

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74 Figure 7-12. Segregation canal at top of cross-section (Photo courtesy of the author) Figure 7-13. Segregation canal at top of cross section (PT grout) (Photo courtesy of the author) Figure 7-14. Soft grout located in segregation canal (Photo courtesy of the author)

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75 Figure 7-15. Equator line separating hard cement from soft grout (Photo courtesy of the author) Figure 7-16. Equator line separating hard cement from soft grout (PT grout) (Photo courtesy of the author)

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76 Figure 7-17. Soft grout vs. water to cement ratio Figure 7-18. Soft grout vs. water to solids ratio

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77 Figure 7-19. Moisture content (0% filler) Figure 720. Moisture content (35% filler)

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78 Figure 7-21. Moisture content (45% filler) Figure 7-22. Moisture contents (mixed at maximum water to solids ratio)

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79 Figure 7-23. Moisture contents (mixed at 15% extra water to solids ratio) (a) (b) Figure 7-24. Comparison of inclined bleed and pressure bleed measurements with respect to w/c

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80 (a) (b) Figure 7-25. Comparison of inclined bleed and pressure bleed measurements with respect to water to solids ratio Figure 7-26. Moisture content C45-0

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81 Figure 7-27. Moisture content C67535 Figure 7-28. Moisture content C82545

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82 Figure 7-29. Bleed water for mixes with and without HRWR admixture Figure 730. Soft grout for mixes with and without HRWR admixture

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83 Figure 7-31. Apparent viscosity for mixes with and without HRWR admixture Figure 7-32. Maximum moisture content versus water/HRWR ratio

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84 Figure 7-33. Bleed water versus water/HRWR ratio Figure 7-34. Soft grout versus water/HRWR ratio

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85 CHAPTER 8 PLAIN GROUT AND PT GROUT COMPARISON The only PT grout that produced soft grout for these experiments was PT4-6. Excess water was the condition that triggered the formation of the soft grout. For this reason, four total tests were conducted on PT4-6 to study how sensitive it is to water to solids ratio Since the relative constituent volumes are not known, the results from the sensitivity study on PT 46 cannot be compared directly to results of testing on plain grout with filler. One indirect method, however, is to compare the results using water to solids ratio. Figure 8-1 shows the flow cone times from the PT4-6 water sensitivity study plotted on top of the results from the plain grout and filler testing. The flow cone times for the PT4-6 test have the same upward concavity and relative magnitude that the plain grout efflux times have at low water to solids ratios. One conclusion that can be drawn from Figure 8-1 is that at low water to solids ratios, the filler material has a lubricating effect on the fluidity of the grout. For example, the test conducted near the 0.3 water to solids ratio range and 0% filler required more HRWR admixture than the tests with filler material, but still had a higher flow cone value. Figure 8-2 shows a plot of the flow cone times versus water to solids ratio for all PT grouts, as well as the filler cement combinations. It is difficult to draw conclusions on how a PT grout will behave in the inclined tube test based exclusively on the flow cone efflux times. For example, PT 5-1 has similar water to solids ratio ranges and magnitudes of flow cone times as PT4-6, but PT4-6 resulted in soft grout and PT 5-1 did not. Additionally, PT 3-3 closely follows the trend of the filler flow cone values, but resulted in no soft grout in the inclined test tube.

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86 Figure 8-3 is a plot of the apparent viscosity readings from the PT4-6 water sensitivity study plotted on top of the results from the plain grout and filler testing. It appears that the apparent viscosity values for the PT4-6 test are far more sensitive to water to solids ratio levels than the plain grouts based on the slope of the PT46 viscosity line. However, the values are roughly less than or equal to 250 mPa*sec. Figure 8-4 below shows a plot of the apparent viscosity versus water to solids ratio for the plain grouts as well as all PT grouts tested. Based on Figure 8-4 below, all PT grouts exhibit highly sensitive apparent viscosity behavior when mixed at the maximum specified water to solids ratio stated by the manufacturer, and 15% extra mixing water. Figure 8-5 is a plot of the amount of soft grout sampled from the plain grout tests, as well as the samples from the PT4-6 sensitivity study. Figure 8-5 reveals the same trend between the plain grout tests and the PT4-6 grout tests. The soft grout quantities for PT4-6 seem to fall between the tests conducted with and without additional filler material. This could possibly be an indication that PT4-6 has up to 35% filler by powder weight. Figure 8-6 and Figure 8-7 show the moisture content values for tests conducted on both prepackaged PT grouts and plain grouts that resulted in no soft grout and soft grout, respectively. Figure 8-6 shows the constant low moisture content along the length of the duct up until the exit region that is almost exclusively observed for incline tests resulting in soft grout The suggested 35% maximum moisture content failure criteria was determined based on a simple theory. If the grout powder and water were not mixed, then the theoretical moisture content of both components would be equal to

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87 the water to solids ratio. Prepackaged PT grouts are typically mixed at water to solids ratios of 0.25 to 0.35. Thus, the maximum recommended limit for moisture content along the length of the duct set forth by the author is 35%. Figure 8-7 reveals a visible trend that can be seen from both the PT grout and plain grout results. Segregation of the grout components has occurred, and extremely high moisture contents are always observed near the top of the inclined tube. Figure 8-8 shows unit weight and mud balance data from the plain grout tests, as well as the results from the sensitivity study conducted on PT 4-6. The horizontal and vertical limits have been adjusted for these plots to show a zoomed in view. The results shown in Figure 8-8 appear to contradict each other. The unit weight values seem to follow the trend from all of the other physical data collected from these experiments: that is PT4-6 results match up with the results from the plain grout tests with additional filler material. However, no definitive conclusions can be drawn from the mud balance comparison plot shown in Figure 8-8. It should be noted that the unit weight test is more precise than the mud balance test. The mud balance test relies on the user to balance the cup using a built in level, which will invariably lead to human error affecting the results. Figure 8-9 below shows a plot of the unit weight values versus water to solids ratio for all PT grouts. Based on Figure 8-9 below, all of the grouts have relatively the same slope, with the unit weight increasing as the water to solids ratio decreases. One possible explanation as to why the other PT grouts have lower unit weight values than PT 4-6 and did not result in soft grout could be that they have larger proportions of lig hter weight supplemental cementitious material such as silica fume or fly ash.

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88 Figure 810 below shows a plot of the mud balance values versus water to solids ratio for all PT grouts. Based on Figure 810 below, it is difficult to draw a definitive conclusion on how the PT grouts will behave in the inclined tube based on the mud balance data.

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89 Figure 8-1. HRWR admixture/flow cone time versus w/s ratio (including PT4-6 tests) Figure 8-2. Flow cone time versus water to solids ratio (including all PT grouts)

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90 Figure 8-3. HRWR admixture/apparent viscosity versus w/s ratio (including PT4-6 tests) Figure 8-4. Apparent viscosity versus water to solids ratio (including all PT grouts)

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91 Figure 8-5. Soft grout versus w/s ratio for varying amounts of filler (including PT46 tests) Figure 8-6. Moisture contents for tests with no soft grout (left: PT grout, right: Plain grout)

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92 Figure 8-7. Moisture contents for tests with soft grout (left: PT grout, right: Plain grout) Figure 8-8. Unit weight (left) and mud balance (right) versus water to solids ratio

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93 Figure 8-9. Unit weight versus water to solids ratio (including all PT grouts) Figure 810. Mud balance versus water to solids ratio (including all PT grouts)

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94 CHAPTER 9 SUMMARY AND CONCLUSIONS The integrity of grouted tendons plays a crucial role in the durability and serviceability of post-tensioned segmental concrete box girder bridges. Multiple bridges in Florida have sustained substantial tendon corrosion due to issues with the PT grout which was incorporated into the bridge structure to increase the durability of the high strength steel tendons and the bridge structure itself. Some common issues with the grout used to encase the PT bridge tendons are bleed water, high chloride levels, voids, and segregated moist unreacted gelatinous material known as soft grout. This study deals primarily with bleed and soft grout, and how different combinations of the grout components affect the formation of both. Before testing began, it was hypothesized that the use of additional filler material such as calcium carbonate (pulverized limestone), which is effectively inert, played a role in the formation of soft grout that was present in bridges within the state of Florida. One hypothesis is that the less dense inert filler material was partially segregating from the cement material and floating to the high points in deviated continuity tendons. An inclined test tube approach was used in conjunction with a CG600 colloidal grout mixing plant in an effort to simulate conditions that would be experienced in a full scale grouting operation. These conditions that were replicated include: large change in elevation over a horizontal length, actual PT stands (12facilitating the filtration and segregation of the grout components after injection, smooth PVC ducts, inlet and exit valves, pumping pressures, and pumping flow rates. Using the inclined test tube approach, a surrogate grout consisting of ASTM C150 Type I/II Portland cement, varying percentages of the filler material calcium

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95 carbonate, varying levels of HRWR admixture, and varying water to cement ratios was tested to determine how the formation of soft grout and bleed was affected by each constituent. The levels of HRWR admixture were varied so that each grout mixture achieved an apparent viscosity that was below 250 mPa*seconds. Six different high performance prepackaged PT grouts were also tested at the maximum specified water to solids ratio, and 15 % extra water. The results from the prepackaged PT grouts were compared to the proxy grout mixtures in detail. The inclined test tube offered a configuration that could be used in a laboratory setting to simulate grout bleed and segregation during full scale mixing and injection. Figure 9-1 shows a diagram of the inclined tube and the mechanisms by which bleed and segregation occur. The change in elevation between the top and the bottom of the inclined test tube causes bleed at the base of the tube to flow upward along the length of the duct due to the pressure head. This bleed then filters or washes out the less dense particles present in suspension, resulting in an unreacted putty grout near the free surface of the grout at the exit of the inclined test tube, and normal hardened grout along the length of the duct. Conclusions from High Performance Prepackaged PT Grout Testing 1. The high performance prepackaged PT grouts tested at the maximum water to solids ratio specified by their manufacturers resulted in no soft grout. The highest moisture content along the length of the duct for all tests on prepackaged PT grouts mixed at maximum water to solids ratio was 25.34%, which was observed nine inches from the exit region of the duct injected with PT 51. 2. With the exception of PT4-6, high performance prepackaged PT grouts were resistant to the 15% extra mixing water test, resulting in no soft grout. PT 2-4 did have a larger moisture content of 44.90% at the exit region of the inclined duct relative to the other four PT grouts, but did not have any visually identifiable soft grout. PT4-6 had a moisture content of 75.67% at the exit region, with 55.6 grams of soft grout.

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96 3. The soft grout that was sampled from the sensitivity analysis conducted on PT46 was exclusively located at the free surface of the grout near the exit region. Conclusions from Plain Grout Testing 1. Mixtures with 45% and 35% additional filler material consistently generated more soft grout than mixtures with 0% additional filler for any given water to solids ratio. 2. All tests conducted at 0%, 35%, and 45% additional filler material stopped bleeding when the water to cement ratio was reduced below 0.45. 3. For a given water to solids ratio, increasing the percentage of filler material will in fact increase the amount of bleed water in the inclined duct. 4. Based on the results from tests conducted with and without HRWR admixtures, it can be concluded that HRWR admixtures decrease the apparent viscosity of the mixture, increase the levels of bleed and segregation, and increase the moisture content near the exit region of the duct. 5. Th e soft grout quantities versus water to solids ratio curves for the plain grouts with 35% and 45% additional filler closely matched the curve from the sensitivity study on PT4-6. The slope, magnitudes, and x-intercept of the curves were all comparable. 6. Moisture content along the length of the duct for tests conducted on plain grouts and prepackaged PT grouts had very similar distributions for tests resulting in soft grout and no soft grout. Tests resulting in soft grout consistently had an excessively high moisture content level near the exit region for both prepackaged PT grouts and plain grouts. 7. At low enough water to cement ratios, large amounts of HRWR admixtures coupled with additional filler material can be used to achieve desirable fluidity characteristics without resulting in segregation of the Portland cement and filler material. Recommendations The following are a set of recommendations and are intended to be used for qualifying prepackaged PT grouts for the FDOT Qualified Products List (QPL): 1. Use the modified inclined test tube to qualify prepackaged PT grouts. 2. PT grouts should be mixed at 15% more mixing water than specified by the manufacturer to assess the robustness of the grout.

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97 3. Moisture content levels should be limited to 35% at any location along the length of the duct. 4. Zero bleed water and soft grout should be present at any given time after injection of the inclined tendon. 5. Filler material should not be allowed in prepackaged PT grouts that will be used in bridge grouting operations.

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98 Figure 9-1. Bleed and segregation mechanism

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99 APPENDIX A MOISTURE CONTENTS The following appendices contain all of the additional test data that was not presented in the main body of this report for both plain grouts and PT grouts. Figure A-1. C30-0 (left), C35-0 (right) Figure A-2. C45-0 (left), C55-0 (right)

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100 Figure A-3. C675-0 (left), C825-0 (right) Figure A-4. C35-35 (left), C45-35 (right) Figure A-5. C55-35 (left), C675-35 (right)

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101 Figure A-6. C825-35 (left), C45-45 (right) Figure A-7. C55-45 (left), C675-45 (right) Figure A-8. C82545

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102 APPENDIX B MOISTURE CONTENTS: ADDITIONAL TESTS Figure B-1. C55-45 (100 mL HRWR) (left), C45-0 (0 mL HRWR) (right) Figure B-2. C675-35 (0 mL HRWR) (left), C825-45 (0 mL HRWR) (right)

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103 APPENDIX C MOISTURE CONTENTS: PT GROUTS Figure C-1. PT 1-4 maximum water (left), PT 1-4 15% extra water (right) Figure C-2. PT2-4 maximum water (left), PT2-4 15% extra water (right)

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104 Figure C-3. PT3-3 maximum water (left), PT3-3 15% extra water (right) Figure C-4. PT4-6 maximum water (left), PT4-6 15% extra water (right) Figure C-5. PT5-1 maximum water (left), PT5-1 15% extra water (right)

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105 Figure C-6. PT6-1 maximum water (left), PT6-1 15% extra water (right)

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106 APPENDIX D PLAIN GROUT DATA Figure D-1. Flow cone vs. water to solids ratio (left), Grout temperature: 0% filler (right) Figure D-2. Grout temperature: 35% filler (left), Grout temperature: 35% filler (right)

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107 Figure D-3. Grout temperature: 45% filler (left), Grout temperature: 45% filler (right) Figure D-4. Mud balance: 0% filler (left), Mud balance: 35% filler (right) Figure D-5. Mud balance: 35% filler (left), Mud balance: 45% filler (right)

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108 Figure D-6. Mud balance: 45% filler (left), Unit weight: 0% filler (right) Figure D-7. Unit weight: 35% filler (left), Unit weight: 35% filler (right) Figure D-8. Unit weight: 45% filler (left), Unit weight: 45% filler (right)

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109 Table D-1. Plain grout summary (0% filler) Mixing experiment 76 54 48 38 47 32 PT C30 0 C35 0 C45 0 C55 0 C675 0 C825 0 Manufacturer PC PC PC PC PC PC dry powder wt (lbs.) 183.9 184.3 183.9 187.7 187.1 185.3 powder temp (F) 70.3 N/A 74.3 71.8 72.8 74.1 water weight (lbs.) 55.18 64.5 82.76 103.4 126.3 153 water temperature (F) 77.6 N/A 79.3 77.3 79 75.3 target water to cement ratio 0.30 0.35 0.45 0.55 0.67 5 0.82 5 theoretical water to solids ratio 0.30 0.35 0.4 4 0.55 0.67 5 0.82 6 theoretical water to cement ratio 0.30 0.35 0.45 0.55 0.67 0.83 Actual % fill 0 0 0 0 0 0 HRWR admixture (mL) 350 250 100 0 0 0 mix time (min.) 10 7 10 6 5 N/A temperature measured from mixer (F) 91.3 88.7 90.7 83.9 83.2 75.9

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110 Table D-1. Continued Post mixing process temperature at hose exit (F) 82.8 81 84.2 78.2 80.1 75.3 flow cone (sec.) 8 5 4.3 4.7 4.1 3.7 mud balance (pcf) 128 122 113 107 100 100 unit wt (pcf) 131.06 125.81 114.18 109.92 105.24 97.73 apparent viscosity (mPa*sec.) 237 134.8 217.1 238.8 100.3 50.61 temperature for DSR readings (F) 82.8 81 84.2 78.2 80.1 75.3 Schupck bleed (mL) 4.66 18 40 68 85 95 Post grouting process flow cone (sec.) 9 5.7 4.4 4.5 3.8 3.7 mud balance (pcf) 126 122 113 109 101 99 unit wt (pcf) 130.78 126.52 115.03 110.07 104.39 95.60 apparent viscosity (mPa*sec.) 224.3 153.5 236.4 265.9 108.1 52.58 temperature for DSR readings (F) 82.9 83.3 81.3 80.8 79.8 76.2 Schupck bleed (mL) 5.71 15 39 67 85 100 pump outlet pressure (psi) 40 N/A 40 40 40 40 duct inlet pressure (psi) 40 N/A 40 40 40 40 discharge at duct exit valve (gal) 2 2 2 2 2 2 duct fill time (sec.) 63 56 75.0 6 50.2 9 66.9 4 92

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111 Table D-1. Continued Dissection weight of soft grout (g) 0 23.7 9 18.8 8 0 35.0 9 71 moisture content at bottom 14.51 17.13 21.86 25.5 22.17 29.02 moisture content at exit 16.3 64.5 56.3 36.9 39.1 67.3 bleed water 0 0 0 600 1820 2244 Table D-2. Plain grout summary (35% filler) Mixing experiment 53 30 43 45 33 PT C35 35 C45 35 C55 35 C675 35 C825 35 Manufacturer PC/CaCO3 PC/CaCO3 PC/CaCO3 PC/CaCO3 PC/CaCO3 dry powder wt (lbs.) 185.2 285.6 289.2 278.9 290.5 powder temp (F) N/A 77 72 71 73 water weight (lbs.) 64.84 83.83 101.8 123.8 158.3 water temperature (F) N/A 74.4 76.6 72.3 75.5 target water to cement ratio 0.35 0.45 0.55 0.675 0.825 theoretical water to solids ratio 0.35 0.29 0.35 0.44 0.54 theoretical water to cement ratio 0.35 0.45 0.55 0.68 0.83 Actual % fill 0.336 0.351 0.360 0.342 0.339

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112 Table D-2. Continued HRWR admixture (mL) 650 300 200 100 0 mix time (min.) 16 11 6 8 8 temperature measured from mixer (F) 104.8 87.1 84.4 86 82.1 Post mixing process temperature at hose exit (F) 88.7 83.8 78.8 80 79.3 flow cone (sec.) 9.4 6.6 5.1 4.7 4.2 mud balance (pcf) 133 127 122 113 109 unit wt (pcf) 136.31 129.65 123.69 115.32 109.79 apparent viscosity (mPa*sec.) 197.4 219.6 223.8 220.9 133.3 temperature for DSR readings (F) 88.7 83.8 78.8 80 79.3 Schupck bleed (mL) 0 13 33 54 75 Post grouting process flow cone (sec.) 10.4 7.49 5.06 4.44 4.27 mud balance (pcf) 132 126 119 114 108 unit wt (pcf) 136.60 129.79 122.98 114.47 107.66 apparent viscosity (mPa*sec.) 222.1 262.1 236.2 228.4 135 temperature for DSR readings (F) 88.3 82.6 N/A 75.3 80.6

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113 Table D-2. Continued Schupck bleed (mL) 0 13 36 57 78.5 pump outlet pressure (psi) N/A 40 40 40 40 duct inlet pressure (psi) N/A 40 40 40 40 discharge at duct exit valve (gal) 2 2 2 2 2 duct fill time (sec.) 57.6 67 74 58 62.5 Dissection weight of soft grout (g) 0 115.37 64.54 97.74 119.51 moisture content at bottom 12.3 15.5 17.6 20.2 20.3 moisture content at exit 28.2 67.7 66.4 62.5 58.8 bleed water 0 0 170 740 1750 Table D-3. Plain grout summary (45% filler) Mixing experiment 31 42 44 46 PT C45 45 PC55 45 PC675 45 PC825 45 Manufacturer PC/CaCO3 PC/CaCO3 PC/CaCO3 PC/CaCO3 dry powder wt (lbs.) 337.6 336.8 337.5 333.5 powder temp (F) 78 73 73 71

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114 Table D-3. Continued water weight (lbs.) 83.83 102.1 127.1 155.5 water temperature (F) 76.4 76.9 76.8 69.8 target water to cement ratio 0.45 0.55 0.675 0.825 theoretical water to solids ratio 0.25 0.30 0.38 0.47 theoretical water to cement ratio 0.44 0.55 0.68 0.83 Actual % fill 0.442 0.449 0.44 0.435 HRWR admixture (mL) 500 300 200 50 mix time (min.) 9 9 8 11 temperature measured from mixer (F) 89.7 87.1 84.3 86.8 Post mixing process temperature at hose exit (F) 84.5 79.3 80.4 81.4 flow cone (sec.) 9.1 6.4 4.7 3.8 mud balance (pcf) 131 124 116 111 unit wt (pcf) 133.61 127.23 119.29 113.19 apparent viscosity (mPa*sec.) 213 159 133 158

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115 Table D-3. Continued temperature for DSR readings (F) 84.5 79.3 80.4 81.4 Schupck bleed (mL) 5.2 21 39 64 Post grouting process flow cone (sec.) 10.1 6.52 4.65 3.74 mud balance (pcf) 131 128 118 111 unit wt (pcf) 134.04 127.66 119.14 112.76 apparent viscosity (mPa*sec.) 250 189 160 149 temperature for DSR readings (F) 86.9 81.6 N/A 83.6 Schupck bleed (mL) 5.2 20 38 68 pump outlet pressure (psi) 40 40 40 40 duct inlet pressure (psi) 40 40 40 40 discharge at duct exit valve (gal) 2 2 2 2 duct fill time (sec.) N/A 98.4 42 59.6 Dissection weight of soft grout (g) 49 123.2 106.2 160 moisture content at bottom 13.1 15.3 19.3 18.2 moisture content at exit 74.2 76.2 61.4 57.5 bleed water 0 260 480 1420

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116 Table D-4. PT results (1) Mixing experime nt 37 40 41 50 51 56 57 PT PT1 4 PT4 6 PT4 6 PT5 1 PT5 1 PT6 1 PT6 1 dry powder wt (lbs.) 192 201 200 227 229 203 200 powder temp (F) 76.2 74.2 74.3 70.1 71.3 0 N/A N/A water weight (lbs.) 65.3 52.1 59.9 52.6 61.04 73.3 62.7 water temperatu re (F) N/A 78 77.1 73.3 76.50 N/A N/A target water to solids ratio 0.327 0.260 0.299 0.232 0.267 0.360 0.360 theoretical water to solids ratio 0.340 0.259 0.299 0.232 0.267 0.360 0.313 mix time (min.) 7.00 8.00 6.00 10.0 0 15.0 0 10.0 0 11.0 0 temperatu re measured from mixer (F) 97.8 92.8 90.3 95.2 92.80 91.9 89.4 Post mixing process temperatu re at hose exit (F) 85.2 85 81.7 83.2 80.40 78.1 78.2 flow cone (sec.) 4.9 7.3 5.2 8 6.52 5.7 7.6 mud balance (pcf) 117 132 124 116 112.00 116 123 unit wt (pcf) 117.45 131.77 127.38 117.87 116.45 117.87 126.95

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117 Table D-4. Continued apparent viscosity (mPa*sec. ) 97.47 265.8 85.83 328.2 144.50 241.3 635.4 temperatu re for DSR readings (F) 85.2 85 81.7 83.2 80.40 78.1 78.2 Schupck bleed (mL) 0 N/A N/A 0 0.00 4 0 Post grouting process flow cone (sec.) 4.96 7.66 5.39 8.12 6.64 7.16 10.4 mud balance (pcf) 115 128 126 111 113.00 119 121 unit wt (pcf) 116.31 132.20 125.11 119.01 116.31 119.86 123.83 apparent viscosity (mPa*sec. ) 110.1 250.2 89.06 262 149.10 467.2 912.3 temperatu re for DSR readings (F) N/A 86.6 82.8 83.8 81.90 N/A N/A Schupck bleed (mL) 0 N/A N/A 0 0.00 5 0 pump outlet pressure (psi) 40 40 40 35 30.00 N/A N/A duct inlet pressure (psi) 40 40 12 40 30.00 N/A N/A discharge at duct exit valve (gal) 2 2 2 2 2 2 2 duct fill time (sec.) 39 90 35.6 65 54.0 0 64 35.1

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118 Table D-4. Continued Dissection weight of soft grout (g) 0 0 79.384 0 0.00 0 0 moisture content at bottom 21.40 14.90 15.00 15.13 13.58 18.88 16.79 moisture content at exit 23.60 20.30 75.70 20.27 22.92 20.38 18.58 Table D-5. PT Results (2) Mixing experiment 26 27 28 29 34 35 36 PT PT2 4 PT4 6 PT1 4 PT3 3 PT4 6 PT3 3 PT2 4 dry powder wt (lbs.) 276 246 243 280 202 223 219 powder temp (F) 77 75 73 75 74 77 77 water weight (lbs.) 87.5 67.5 71 87.5 62.1 80.5 80.5 water temperature (F) 76.3 74.8 73.9 76.5 76.2 76.3 76.8 target water to solids ratio 0.318 0.270 0.284 0.318 0.311 0.366 0.366 theoretical water to solids ratio 0.317 0.274 0.292 0.312 0.307 0.361 0.367 mix time (min.) 8.00 9.00 11.0 0 9.00 8.00 7.00 8.00 temperature measured from mixer (F) 94.1 96.3 98.3 89.6 90.5 91.1 90.1

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119 Table D-5. Continued Post mixing process temperature at hose exit (F) 86.8 84.1 85.5 84.1 71.8 82.7 80.4 flow cone (sec.) 7.5 6.4 6.3 5.9 5.3 4.6 5.7 mud balance (pcf) 124 126 120 121 128 119 120 unit wt (pcf) 123.97 130.78 121.99 122.70 128.23 117.59 120.28 apparent viscosity (mPa*sec.) 425 162.2 249.4 352.2 100.4 167.4 159.1 temperature for DSR readings (F) 86.8 84.1 85.5 84.1 71.8 82.7 80.4 Schupck bleed (mL) N/A 0 0 1.9 0 2 1.6 Post grouting process flow cone (sec.) 8.1 6.6 6.8 7.4 5.4 5 5.4 mud balance (pcf) 123 132 119 124 128 118 120 unit wt (pcf) 124.96 131.06 121.70 123.40 128.51 119.50 119.86 apparent viscosity (mPa*sec.) 394 165.6 290.9 423.2 103 189.2 142.1 temperature for DSR readings (F) 86.4 82.1 83.8 79.9 84.2 85.1 82.7 Schupck bleed (mL) N/A 0 0 1.3 0 2 0 pump outlet pressure (psi) 40 40 40 40 40 40 40

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120 Table D-5. Continued duct inlet pressure (psi) 40 40 30 40 40 40 40 discharge at duct exit valve (gal) 2 2 2 2 2 2 2 duct fill time (sec.) 57.6 69.2 58.9 69.5 58 74 63 Dissection weight of soft grout (g) 0.00 55.57 0.00 0.00 159.22 0.00 0.00 moisture content at bottom 17.90 15.22 17.40 18.90 16.00 21.20 20.80 moisture content at exit 18.90 72.70 16.60 18.30 72.70 21.80 44.90

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121 REFERENCES (2007, April 30). EN 445 Grout for pestressing tendons Test methods. European Committee for Standardization. (2012). ASTM C150-12 Standard Specification for Portland Cement. West Conshohocken: ASTM International. (2012). ASTM C1741-12 Standard Method for Bleed Stability of Cementitious Posttensioning Tendon Grout. ASTM. 318, A. C. (2013). ACI Concrete Terminology. Farmington Hills: American Concrete Institute. Cervantes, V., & Roesler, J. (July 2007). Ground Granulated Blast Furnace Slag. Urbana, Illinois: University of Illinois; Department of Civil and Coastal Engineering. Committee, P. G. (2003). PTI Specification for Grouting of Post-Tensioned Structures. USA: Post-Tensioning Institute. Committee, P. G. (2003). PTI Specification for Grouting of Pot-Tensioned Structures. USA: Post-Tensioning Institute. Corven, J., & Moreton, J. (May 2004). Post-Tensioning Tendon Installation and Grouting Manual. Federal Highway Administration. El -Didamony, H., Salem, T., Gabr, N., & Mohamed, T. (1994). Limestone as a Retarder and Filler in Limestone Blended Cement. Ceramics. Hamilton, D. H. (2013). Improved Test Methods for Evaluating Fresh and Hardened Properties of High Performance Post-Tensioing Grout. Gainesville: University of Florida. Hartt, W. H., & Venugopalan, S. (April 2002). Corrosion Evaluation of Post-Tensioning Tendons on the Mid Bay Bridge in Destin, Florida. Tallahassee, Florida: FODT. Hawkins, P., Tennis, P., & Detwiler, R. (2003). The Use of Limestone in Portland Cement: A State of the Art Review. Portland Cement Association. Jue, M. (2012). Effect of Inert Nanoparticles on Cement Hydration. NIN REU RESEARCH ACCOMPLISHMENTS 96-97. Mario Paredes, P. (June 17, 2013). PT Grout Segregation. Gainesville: Florida Department of Transportation.

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122 Martini, S. A., & Nehdi, M. (August 2009). Coupled Effects of Time and High Temperature on Rheological Properties of Cement Pastes Incorporating Various Superplastisizers. Journal of Material in Civil Engineering ASCE. Montemor, M., Simoes, A., & Ferreira, M. (2003). Chloride Induced Corrosion on Reinforcing Steel: From the Fundamentals to the Monitoring techniques. Elsevier, 491-502. Pouliotte, J. (2012). PT Grouting and Corrosion Issues in Florida. Tallahassee: Florida Department of Transportation. Schokker, A., Koester, B., Breen, J., & Kreger, M. (October 1999). Development of High Performance Grouts for Bonded Post-Tensioning Structures. Austin, Texas: Center for Transportation Research. Suarez, J., Zhang, J., Hsuan, G., & Hartt, W. (August 2006). Polyethylene Duct Cracking in Posttensioning Tendons in Florida Segmental Bridges. Journal of Materials in Civil Engineering ASCE 581-587. Trejo, D., Pillai, R. G., Hueste, M. D., Reinschmidt, K. F., & Gardoni, P. (April 2009). Parameters Influencing Corrosion and Tension Capacity of Post-Tensioning Strands. ACI Materials Journal 144-153.

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123 BIOGRAPHICAL SKETCH Alexander Randell was an aspiring bridge engineer. He was mainly interested in complex bridge design including, but not limited to: segmental bridges, cable stay bridges, suspension bridges, draw bridges, steel truss bridges, etc. He was mainly interested in the design and construction aspects of bridge engineering.