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Glowcrete

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Glowcrete

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  1. Glowcrete June 6, 2006 Northwestern University Engineering Design and Communication Section 15 Team 3 Andy Long James Rein Adrienne Smith Lauren Smith Client: Paul Preissner, Qua'Virarch

  2. Agenda • Overview of Design Problem • Background Research • Proposed Procedures • Preliminary Results • Benefits of Proposed Procedures • Recommended Next Steps • Question and Answer Session

  3. Need for Self-Illuminating Concrete • Self-illuminating concrete would be useful in various nighttime applications • dark parking garages • roadside jersey walls • runways • Benefits include: • increase safety • reduce lighting costs • Little previous research has been conducted on self-illuminating concrete Jersey Walls Runways Parking Garages

  4. Mission of Project • Develop methods for creating self-illuminating concrete • Develop methods for testing self-illuminating concrete • Determine composition of material that optimizes self-illuminating and structural properties

  5. Approach • Conduct background research to identify materials needed to create self-illuminating concrete • Consider various methods for applying these materials to concrete • Evaluate properties that should be tested

  6. Background Research

  7. Concrete

  8. Concrete vs. Cement • This project worked with cement rather than concrete • Cement is a constituent of concrete • Aggregate is used to increase hardness and strength but does not affect adhesive properties • Cement results should therefore be analogous to concrete results • Cement provides a flat surface that is necessary when conducting certain material tests

  9. Phosphorescence • Type of light emission that lasts for a relatively long time after external energy has been removed • Due to substances known as phosphors • Phosphors consist of a host lattice doped with an activator ion • Activator ion stores the energy and emits photons

  10. Phosphorescent Powder Used Strontium aluminate doped with europium and dysprosium • Longest lasting • Brightest glow • Expensive ($38 / lb) This material was chosen for use in this project

  11. Thin Layer Approach • Benefits: • Amount of glow powder used is minimized • Glow powder will not be wasted in center of material (where light cannot penetrate to) • Should not influence the structural properties of the material as a whole Thin Phosphorescent Cement Layer Normal Cement

  12. Project Focus Determine whether methods can be developed for making self-illuminating cement by adhering a separate phosphorescent layer to the cement core

  13. Requirements • Entire material must be strong enough to be used structurally • Top phosphorescent material must adhere to the cement core • Phosphorescence must last for a lengthy duration (at least four hours)

  14. Procedures for Making Samples

  15. Procedure for Making Samples • Overview: • Assemble molds and seal edges • Pour phosphorescent cement • Smooth to proper thickness and remove air bubbles • Pour pure cement to complete bulk of sample • Smooth and remove air bubbles from sample • Store under proper conditions

  16. Procedure for Making Samples STEP 1 • Assemble molds and seal edges STEP 2 • Pour phosphorescent cement

  17. Procedure for Making Samples STEP 3 • Smooth to proper thickness using smoother SMOOTHER • Produces a consistent1 mm layer

  18. Procedure for Making Samples STEP 4 • Remove air bubbles by gently bouncing STEP 5 • Pour pure cement to create bulk of sample

  19. Procedure for Making Samples STEP 6 • Smooth top using straight edge • Remove air bubbles by gently bouncing STEP 7 • Gently place lid on top without closing completely

  20. Procedure for Making Samples STEP 8 • Store wrapped in wet paper towels and in plastic bags for 16 hours STEP 9 • Remove from molds • Store for 8 days in saturated CaO water

  21. Product of Procedure • Cement bar that has a phosphorescent cement thin layer and pure cement bulk • Methods analogous to real world laying (though opposite order): • Lay bulk material, smooth • Lay thin layer, smooth

  22. Procedures for Testing

  23. Testing Goals • determine if thickness affects phosphorescence • determine ratios of water and glow powder content in the thin layer that optimize adhesion and phosphorescence

  24. Procedure for Testing Samples • Overview: • Preparation of sample • Sand down non-phosphorescent surface (needed for adhesion testing) • Adhesion testing • Three-point bend test • Compression test • Microscopy • Phosphorescence testing

  25. Force applied by machine Compression Surface Tension Surface Force applied by machine Adhesive Testing: Three Point Bend Test • Place thin layer in tension • Apply force, cause fracture • Observe using microscopy whether thin layer rips off during stress (sign of poor adhesion) • Observe using microscopy if fractures propagate along layer boundary (sign of poor adhesion)

  26. Compression Surface Force applied by machine Adhesive Testing: Compression Test • Place thin layer in compression • Apply force with spherical indenter, cause fracture • Observe using microscopy whether thin layer flakes off due to stress (sign of poor adhesion) • Observe using microscopy if fractures propagate along layer boundary (sign of poor adhesion)

  27. Phosphorescence Testing • Light sources used: • White light: Ott-Lite 13W bulb • UV light: Phillips TLD 15W/08 bulb • Charging times tested: • 1 minute • 10 minutes • Methods • Discharge samples • Expose thin phosphorescent layer of cement to light for charging time • Remove light and use light meter to record phosphorescence until phosphorescence terminates • Normalize these values based on surface area • Repeat for each sample

  28. Water and Glow Powder Ratios

  29. Results

  30. Effect of Thickness • Surfaces of samples were exposed to light source • Cross section (previously covered) was observed cross section

  31. Effect of Thickness • Surfaces of samples were exposed to light source • Cross section (previously covered) was observed • Only edges glowed • Indicated that light did not penetrate through the surface of the sample • Justifies use of very thin phosphorescent layer Glow cross section

  32. Preliminary Compression Test Results Controls Pure Cement with 2.1:1 Water Glow Powder Throughout Sample with 2.5:1 Glow Powder and with 2.1:1 Water

  33. Preliminary Compression Test Results 1.3:1 Glow Powder, 1.7:1 Water 2.5:1 Glow Powder, 2.1:1 Water

  34. Preliminary Compression Test Results *All ratios are by mass of cement to mass of phosphorescent powder or mass of water

  35. Preliminary Three Point Bend Test Results • Observed boundary layer under light microscope • No cracks on boundary layers for any samples • Poor test for adhesion

  36. Preliminary Compression Test Results Controls (UV Light) Cross section (UV Light) 2.5:1 Glow Powder, 2.4:1 Water

  37. Preliminary Results: Effect of Water 2.5:1 Glow Powder, Varying Water (UV Light)

  38. Preliminary Results: Effect of Glow Powder 2.1:1 Water, Varying Glow Powder (UV Light)

  39. Preliminary Results: Effect of Time 2.5:1 Glow Powder, Varying Water (UV Light) Time Elapsed = 1 minutes Time Elapsed = 0 minutes Time Elapsed = 2 minutes

  40. Discussion

  41. Failure Modes and Effect Analysis Procedures • Glow powder not evenly dispersed throughout sample • Bubbles • Waiting too long between layer and bulk All effects can be offset by using proper technique when creating samples

  42. Failure Modes and Effect Analysis End Product • Layer chips off • Temporarily no glow • Glowing of layer gradually wears off

  43. Next Steps • Repetition of cement tests to confirm results • Consultation of experts • Search for longer lasting glow powder • Production and testing of analogous concrete samples • Quantitative compressive strength tests and phosphorescent tests • Durability tests • Large scale tests

  44. Conclusion • Cement materials can be made that have a phosphorescent thin layer • Properties of these materials can be tested • Compression test: good indicator of adhesion • Three point bend test: poor indicator of adhesion • Length of phosphorescence is short • Work suggests that material may have potential for applications, given more research

  45. Acknowledgements • Mr. Paul Preissner • Professors Kathleen Carmichael and Arthur Felse • Professors Hamlin Jennings and Jeffrey Thomas • Dr. James Zaykoski and Mr. Curtis Martin • Mr. Mark Seniw and Professor Kathleen Stair • Professor Thomas Mason and Ms. Ni Wansom • Mr. Steve Jacobson • Fellow students

  46. GlowCrete QUESTION AND ANSWER Northwestern University Engineering Design and Communication June 6, 2006

  47. Methods for Qualitatively Observing Adhesion

  48. X-Ray 5SrO∙4Al2O3 SrAl2O4