1. Northwestern University Client: Paul Preissner, Qua'Virarch
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
Parking Garages
Jersey Walls
Runways

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 consistent 1 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. Adhesive Testing: Three Point Bend Test
Force applied by machine
Compression Surface
Tension Surface
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. Adhesive Testing: Compression Test
Force applied by machine
Compression Surface
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
Go through some of the preliminary test results on the effect of:
thickness
adhesion tests (both compression and 3-point bend)
phosphorescence

30. Effect of Thickness Surfaces of samples were exposed to light source
Cross section (previously covered) was observed
Preliminary tests performed to determine the effect of thin layer thickness of phosphorescence
Tests done on samples with 5:1 glow powder ratio
Cross section covered with electrical tape, surface is exposed to light for 10 min
Took light off and observed
cross section

31. Effect of Thickness Glow
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
Light did not penetrate deep
Therefore thickness does not matter and was not tested further
cross section

32. Preliminary Compression Test Results
Controls
Before discussing results, show the behavior of controls
Point out which is which
Both have clean fractures, no visible material distortion around the crater
This means that mixing the glow powder throughout doesn’t cause the material to have poor reactions to compression
Therefore, if we see flaking or cracking, this might mean that the thin layer is adhered poorly
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
Shows representative results.
Left – good adhesion – no distortion – no cracking or flacking
Right – flaking, and indent actually broke away
2.5:1 Glow Powder, 2.1:1 Water
1.3:1 Glow Powder, 1.7:1 Water

34. Preliminary Compression Test Results
Summary of our 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. Northwestern University
GlowCrete
QUESTION AND ANSWER
Northwestern University
Engineering Design and Communication
June 6, 2006

47. Methods for Qualitatively Observing Adhesion

48. X-Ray
SrAl2O4
5SrO∙4Al2O3