MASTER'S THESIS DEFENSE PRESENTATION (Sept 16)

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<ul><li><p>US Army Corps of Engineers</p><p>BUILDING STRONG</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Background: The State of the Art &amp; </p><p>Path Moving Forward Issues Surrounding Portland </p><p>Cement Concrete</p><p> Reduced Carbon Footprint</p><p> High Firing Temperature Approximately 1400C</p><p> Alternative Binding Materials</p><p> Geopolymers</p><p> Motivations</p><p> Weak Chemical Bonding</p><p> Corrosion Mitigation</p><p>2</p><p>Figure 1. Corrosion of steel reinforcement bar </p><p>(courtesy of buildingfacades.com)</p><p>Figure 2. The Concrete of Tomorrow. By-</p><p>products of other processes and materials </p><p>serving as reasonable alternatives to PCC. </p><p>(courtesy of civilengineeringforums.com)</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Scope of Current Research</p><p> Previous Research Efforts</p><p> Weiss et al. (2009)</p><p> Allison et al. (2012)</p><p> Moser et al. (2013)</p><p> Objective of This Study</p><p> Study interaction between novel </p><p>enamel coatings and various </p><p>geopolymeric matrices</p><p>3</p><p>Vitreous Enamel</p><p>Pozzolanic Materials</p><p>Novel Material</p><p>Figure 2. Vitreous </p><p>enamel coated pin </p><p>(courtesy of Moser </p><p>et al. (2013)</p><p>Figure 1. Test rods having cement </p><p>applied to melted glass at the </p><p>surface of the rods (courtesy of </p><p>Weiss et al. (2009)</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Materials Utilized During This Research Fiber Types</p><p> Straight</p><p> Fibercon International </p><p>CAR-25-CDM</p><p> Kinked</p><p> Dramix ZP 305</p><p> Undulated</p><p> Nycon-SF Type V High </p><p>Performance Steel Fiber</p><p> Coatings</p><p> Ferro SI-677 A Black Ground </p><p>Coat</p><p> Matrix Materials</p><p> Fly Ash</p><p> Metakaolin</p><p> Portland Cement</p><p>4</p><p>Figure 1. CAR-25-CDM</p><p>(straight fibers)</p><p>Figure 3. Dramix ZP 305</p><p>(kinked fibers)</p><p>Figure 2. Type V High Performance </p><p>(undulated fibers)</p><p>Figure 4. Matrix materials were fly ash (left), </p><p>metakaolin (middle), and portland cement (right)</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Specimen Preparation: Application </p><p>of Reactive Vitreous Enamel Coating</p><p>5</p><p>Fibers were cleaned using ethyl alcohol to remove oils and impurities</p><p>Fibers then dipped in fresh enamel for a vitreous coating. Afterwards, pozzolans were applied for RVEC fibers.</p><p>Placed in furnace at 811C for 2.5 minutes to harden to coating </p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Specimen Preparation: Embedment </p><p>of Coated and Uncoated Fibers </p><p>6</p><p>Coated and uncoated fibers mounted onto fiber platform</p><p>Mounting cups filled with fresh </p><p>mortar and fibers embedded</p><p>Fiber embedded specimens cured </p><p>for 28 days</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Experimental Methods: Mechanical </p><p>&amp; Chemical Characterization </p><p> Pullout Testing (mech.)</p><p> Push-out Testing (mech.)</p><p> Scanning Electron </p><p>Microscopy (SEM)</p><p> Energy Dispersive X-ray </p><p>(EDX) (chem.)</p><p>7</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Experimental Methods: Fiber Pullout </p><p>Testing Instron 4206 30k Universal </p><p>Testing Machine</p><p> 1kN Load Cell</p><p> Pullout rate of 0.05 inch min-1</p><p>(0.021 mm sec-1 )</p><p> Failure of fibers prior to failure of </p><p>the bond between the fiber and </p><p>matrix</p><p> Push-out testing was then </p><p>considered as a potential </p><p>alternative. </p><p>8</p><p>Figure 1. Overall setup </p><p>employed to perform </p><p>pullout testing</p><p>Figure 2. Fiber remaining in </p><p>grips of Instron machine </p><p>once the pullout test had </p><p>concluded</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Experimental Methods: Push-out Testing</p><p> Fiber Push-Out Test</p><p>9</p><p>A mechanical test performed to measure the </p><p>matrix/fiber interface de-bonding energy and the </p><p>effects of frictional sliding between the matrix and </p><p>the fiber.</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Experimental Methods: Push-Out </p><p>Testing (cont.)</p><p>10</p><p> Struers DuraScan-70 Fully </p><p>Automatic Hardness Tester</p><p> 0.098 N (10 gf) to 98.10 N (10 kgf) </p><p>load capacity</p><p> Interface 1500 Low Capacity </p><p>LowProfile Load Cell</p><p> 250 N load capacity</p><p> Aluminum Platen</p><p> ecos Workflow software </p><p>package</p><p> MicroPunch data acquisition </p><p>script (developed by ERDC </p><p>personnel)Struers DuraScan-70 </p><p>hardness tester</p><p>Interface 1500 Load Cell </p><p>(blue) with aluminum platen </p><p>mounted atop (silver)</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Experimental Methods: Push-Out </p><p>Testing (cont.)</p><p> Determine the site where </p><p>testing will be conducted</p><p> Push-out test is perform on the </p><p>fiber at the center of a sample</p><p> Verification of push-out by </p><p>visual inspection</p><p>11</p><p>Specimen during Push Out </p><p>testing</p><p>Specimen after testing</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Experimental Methods: SEM and </p><p>EDX Spectroscopy</p><p> Polished sample</p><p> Requires special </p><p>preparation</p><p> FEI Nova NanoSEM 630 </p><p>field emission SEM</p><p> 15 kV voltage source</p><p> Backscattered electron </p><p>detector</p><p> Bruker Quantax AXS </p><p>solid-state EDX detector</p><p>12</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Results &amp; Discussion: Pullout </p><p>Testing</p><p>13</p><p>Comparison of the pullout testing results of </p><p>uncoated and coated kinked fibers embedded </p><p>in metakaolin and fly ash-based geopolymer </p><p>mortars.</p><p>Comparison of the pullout testing results of </p><p>uncoated and coated undulated fibers </p><p>embedded in metakaolin and fly ash-based </p><p>geopolymer mortars.</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Results &amp; Discussion: Pullout Testing (cont.)</p><p>14</p><p>Comparison of the pullout testing results of uncoated and coated </p><p>straight fibers embedded in metakaolin and fly ash-based </p><p>geopolymer mortars.</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Results &amp; Discussion: Optical </p><p>Microscopy of Fibers Post-Pullout Test </p><p>15</p><p>An uncoated straight fiber that had been </p><p>embedded in fly ash-based geopolymer </p><p>mortar and pulled out completely during </p><p>pullout testing.</p><p>A reactive vitreous enamel coated kinked </p><p>fiber that had been embedded in fly ash-</p><p>based geopolymer mortar and exhibited </p><p>necking during pullout testing. </p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Results &amp; Discussion: Optical </p><p>Microscopy of Fibers Post-Pullout Test </p><p>(cont.) </p><p>16</p><p>A reactive vitreous enamel coated undulated fiber that had been embedded in </p><p>fly ash-based geopolymer mortar and exhibited necking during pullout testing. </p><p>(a) Flat, rigid side of the undulated fiber and (b) the undulated, smooth side of </p><p>the same fiber.</p><p>a b</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Small Study: Tensile Tests Performed on </p><p>Each Fiber Type Under Various Treatments</p><p> Three treatment </p><p>configurations</p><p> Untreated (no heat)</p><p> Annealed (811C)</p><p> Quenched in tap water </p><p>immediately following </p><p>heat exposure (811C)</p><p> Exposure to heat resulted in </p><p>approximately 40 60% </p><p>decrease to tensile strength </p><p>for each fiber type.</p><p>17</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Lessons Learned from Pullout </p><p>Testing</p><p>18</p><p> Not the most efficient method of </p><p>evaluating bond strengths</p><p> Heat exposure decreased fiber </p><p>tensile strengths</p><p> Fibers failed prematurely</p><p> Evident by necking of fibers</p><p> Find an alternative technique of </p><p>evaluating bond strength</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Results &amp; Discussion: Push-Out </p><p>Testing</p><p>19</p><p>Uncoated straight fibers embedded in fly ash-based geopolymer </p><p>mortar that has undergone push-out testing.</p><p>Reactive vitreous enamel coated straight fibers embedded in </p><p>fly ash-based geopolymer mortar that has undergone push-</p><p>out testing.</p><p>Fly Ash Specimens, Uncoated, 1.0 mm Fly Ash Specimens, Coated, 1.0 mm</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Results &amp; Discussion: Push-Out </p><p>Testing (cont.)</p><p>20</p><p>Note the change in behavior of curves a &amp; b versus that of curves c &amp; d.</p><p>a</p><p>b d</p><p>c</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Results &amp; Discussion: Optical </p><p>Microscopy of Push-Out Specimens</p><p>21</p><p>An uncoated straight fiber embedded in metakaolin-based </p><p>geopolymer mortar that has undergone push-out testing.</p><p>A reactive vitreous enamel coated straight fiber embedded in </p><p>metakaolin-based geopolymer mortar that has undergone </p><p>push-out testing.</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Results &amp; Discussion: Avg. Bond Strengths of Fibers</p><p>(Fly Ash-Based Geopolymer Mortar)</p><p>22</p><p>0.00</p><p>5.00</p><p>10.00</p><p>15.00</p><p>20.00</p><p>25.00</p><p>1.00 1.50 2.00</p><p>Avg</p><p>. B</p><p>on</p><p>d S</p><p>tre</p><p>ng</p><p>th (</p><p>MP</p><p>a)</p><p>Sample Thickness (mm)</p><p>Uncoated Fibers</p><p>Coated Fibers</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Results &amp; Discussion: SEM Imaging of Sample </p><p>(Metakaolin Coated)</p><p>23</p><p>Overview of metakaolin-based geopolymer mortar</p><p>(200x mag.)</p><p>Interface between metakaolin-based geopolymer paste and </p><p>sand particle</p><p>(1,000x mag.)</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Results &amp; Discussion: SEM Imaging of Sample </p><p>(Metakaolin Coated) (cont.)</p><p>24</p><p>Reactive vitreous enamel coated fiber </p><p>(Overview of entire site of embedment)</p><p>(200x mag.)</p><p>Matrix-coating Interfacial Transition </p><p>Zone (ITZ) of a coated fiber</p><p>(1,000x mag.)</p><p>Microcracking at the matrix-coating ITZ </p><p>of a coated fiber</p><p>(4,000x mag.)</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Results &amp; Discussion: SEM Imaging of Sample </p><p>(Metakaolin Coated) (cont.)</p><p> At the matrix-coating interface, </p><p>pronounced chemical shrinkage is </p><p>observed.</p><p> Shrinkage is not isolated only to </p><p>this interface. This characteristics </p><p>to prevalent throughout the entire </p><p>matrix.</p><p> This shrinkage is the main reason </p><p>for the decreased bond strength </p><p>values. The shrinkage cracking is effectively </p><p>de-bonding the coated fiber from the </p><p>metakaolin matrix at the interface.</p><p>25</p><p>Chemical Shrinkage Crack</p><p>Metakaolin Matrix Vitreous Enamel</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Results &amp; Discussion: Energy Dispersive X-ray </p><p>(EDX) Spectroscopy</p><p>(Metakaolin Specimen)</p><p>26</p><p>Line scan and elemental mapping of Matrix-Enamel-</p><p>Fiber Interfacial Transition Zones (ITZs)</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Results &amp; Discussion: SEM Imaging of Sample </p><p>(Cement Coated)</p><p>27</p><p>Straight Steel FiberVitreous </p><p>EnamelReactive Topcoat</p><p>(cement)</p><p>The image above is an expanded </p><p>view of the portland cement control </p><p>matrix.</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Results &amp; Discussion: SEM Imaging of Sample </p><p>(Cement Coated) (cont.)</p><p>28</p><p>Fiber-Vitreous Enamel Interface</p><p>Straight Steel Fiber Fiber-Enamel Interface</p><p>Vitreous Enamel </p><p>Reactive Vitreous Enamel-Cement Matrix </p><p>Interface</p><p>Vitreous Enamel</p><p>Reactive </p><p>Vitreous </p><p>Enamel CoatingCoating-Matrix </p><p>Interface</p><p>Portland </p><p>Cement Matrix</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Results &amp; Discussion: Energy Dispersive X-ray </p><p>(EDX) Spectroscopy</p><p>(Cement Specimen)</p><p>29</p><p>Line scan and elemental mapping of Matrix-Enamel-Fiber </p><p>Interfacial Transition Zones (ITZs)</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Results &amp; Discussion: SEM Imaging of Sample </p><p>(Fly Ash Coated) </p><p>30</p><p>Overview of fly ash-based geopolymer mortar matrix</p><p>(200x mag.)</p><p>Reactive vitreous enamel coated fiber (Overview of entire </p><p>site of embedment)</p><p>(200x mag.)</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Results &amp; Discussion: SEM Imaging of Sample </p><p>(Fly Ash Coated) (cont.)</p><p> The white particles throughout </p><p>the enamel have elemental </p><p>compositions consistent with </p><p>that of chromium.</p><p> Chromium oxide particles</p><p> The appearance of separation </p><p>at the Enamel-Matrix ITZ is </p><p>actually less than perfect </p><p>polishing.</p><p>31</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Results &amp; Discussion: Energy Dispersive X-ray </p><p>(EDX) Spectroscopy</p><p>(Fly Ash Specimen)</p><p>32</p><p>Line scan and elemental mapping of Fiber-Enamel-</p><p>Matrix Interfacial Transition Zones (ITZs)</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Results &amp; Discussion: Energy Dispersive </p><p>X-ray (EDX) Spectroscopy</p><p>33</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Conclusions Reactive vitreous enamel coating enhances bond strength on </p><p>the order of up to 5.7 times</p><p> EDX spectroscopy shows smoother transitions in elemental </p><p>composition across the ITZs of coated specimens, translating to </p><p>these higher bond strengths</p><p> Overall toughness is increased in cementitious samples </p><p>containing coated fibers versus those with uncoated fibers</p><p> Higher standards of deviation in coated samples are as a result </p><p>of the non-uniformity of the coating</p><p> Overly thick coating negates mechanical anchorage in fibers of </p><p>deformed geometries</p><p>34</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Future Work</p><p> Nanomechanical</p><p>characterization of </p><p>reactive vitreous enamel </p><p>coated fibers</p><p> Uniform application of </p><p>coatings to fiber </p><p>reinforcement</p><p> Effects of pore size </p><p>distribution on bond </p><p>strength</p><p>35</p><p>Nanoindentation of ITZ between fly ash-based geopolymer and </p><p>steel (courtesy of Allison et al. (2015))</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Acknowledgements</p><p>U.S. ERDC Personnel</p><p> Dr. Charles A. Weiss, Jr., GSL</p><p> Dr. Robert D. Moser, GSL</p><p> Henry Blake, ITL</p><p> Kevin Torres-Cancel, GSL</p><p> Brett A. Williams, GSL</p><p> Jason Morson, GSL</p><p> Wendy Long, GSL</p><p> Stephen Murrell, GSL</p><p>Jackson State Personnel</p><p> Dr. Lin Li</p><p> Dr. Fashard Amini</p><p> Dr. Wei Zheng</p><p> Shanetta Cristler</p><p>36</p><p>Id like to thank the ERDC 6.1 Military Engineering Basic Research </p><p>Program for providing the funding necessary to execute the research </p><p>presented herein. </p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Thank You For Listening!</p><p> Questions???</p><p> Comments???</p><p>37</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Experimental Methods: Push-Out </p><p>Testing (cont.)</p><p> Using the EcoWorks software, </p><p>center the platen underneath </p><p>the Overview Camera (OC).</p><p> After naming the sample and </p><p>indicating testing parameters </p><p>(i.e. load), use the Evaluation </p><p>Camera (EC) to focus and find </p><p>center of hole in platen.</p><p> The hole was drilled in an </p><p>effort to insure that the bottom </p><p>of a fiber isnt obstructed </p><p>during push out testing.</p><p>38</p><p>Evaluation Camera view of the center of hole in platen</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Push Out Test Procedure Overview</p><p>(cont.)</p><p> The EC is then raised and the </p><p>push out specimen is placed </p><p>on the platen with the fiber </p><p>positioned over the hole.</p><p> Afterwards, the site of </p><p>indentation is established </p><p>using the program. Should be </p><p>as close to the center as </p><p>possible.</p><p>39</p><p>Evaluation Camera view of the center of </p><p>a fiber.</p><p>Overview of push-out test setup </p><p>including a sample prepared for testing.</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Results &amp; Discussion: Avg. Bond Strengths of Fibers</p><p>(Metakaolin-Based Geopolymer Mortar)</p><p>40</p><p>0.00</p><p>2.00</p><p>4.00</p><p>6.00</p><p>8.00</p><p>10.00</p><p>12.00</p><p>14.00</p><p>16.00</p><p>1.00 1.50 2.00</p><p>Avg</p><p>. B</p><p>on</p><p>d S</p><p>tre</p><p>ng</p><p>ths</p><p> (M</p><p>Pa</p><p>)</p><p>Sample Thickness (mm)</p><p>Uncoated Fibers</p><p>Coated Fibers</p></li><li><p>Innovative solutions for a safer, better worldBUILDING STRONG</p><p>Results &amp; Discussion: Avg. Bond Strengths of Fibers</p><p>(Portland Cement Mortar)</p><p>41</p><p>0.00</p><p>1.00</p><p>2.00</p><p>3.00</p><p>4.00</p><p>5.00</p><p>6.00</p><p>7.00</p><p>8.00</p><p>9.00</p><p>1.00 1.50 2.00</p><p>Avg</p><p>. B</p><p>on</p><p>d S</p><p>tre</p><p>ng</p><p>ths</p><p> (M</p><p>Pa</p><p>)</p><p>Sample Thickness (mm)</p><p>Uncoated Fibers</p><p>Coated Fibers</p></li></ul>