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Development and Analysis of Phosphorescent and Translucent Concrete:
A study of fabricating and testing the applications of an optical fiber matrix and phosphorescent strontium aluminate powder additive to a cementitious mixture.
Ross Bednar '18 & Sam Merritt '18 Swarthmore College, Department of Engineering
Advisor: Faruq Siddiqui Engineering 090 - Senior Design
Spring 2018
Acknowledgement:
We would like to thank our faculty advisor Prof. Faruq Siddiqui as well as J. Johnson, Prof.
Lynn Molter and Prof. Carr Everbach without whom our project would have not been feasible.
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Table of Contents:
Abstract ........................................................................ .
Introduction .................................................................... .
• l.l Research Background and Motivation
• l.2 Research Objectives
• l.3 Organization of Paper
Description of Materials ...................................................... .
• 2.l. Phosphorescent Concrete o 2.l.l Introduction
o 2.l.2 Previous Works
o 2.l.3 Rare Earth Doped Strontium Aluminate
• 2.2 Translucent Concrete o 2.2.1 Introduction
o 2.2.2 Fiber Optic filaments
o 2.2.3 Methods of Application
• 2.3 Recycled Waste Glass Concrete Sand
• 2.4 Optical Fiber Filaments • 2.5 Phosphorescent Doped Strontium Aluminate Powder
• 2.6 Cost of Materials Used
Experimental Procedure ....................................................... .
• 3.1 Design
• 3.2 Fabrication
• 3.3 Testing Design and Procedure
o 3.3.1 Testing of Phosphorescent Samples
o 3.3.2 Testing of Phosphorescent Sample
Experimental Results ........................................................ .
• 5.1 Phosphorescence Tests o 5.l.l Exposure Time and Illuminance Duration
o 5.l.2 Exposure time and Illuminance Intensity
• 5.2 Translucence Tests o 5.l.l Acceptance Angle and Transmittance
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5
6
10
13
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Discussion of Results ........................................................ .
• 6.1 Translucence Tests o 6.l.l Acceptance Angle and Transmittance
• 6.2 Phosphorescence Tests o 6.2.1 Exposure Time and Illuminance Duration
o 6.2.2 Exposure time and Illuminance Intensity
Conclusions .................................................................... .
• 7.1 Summary • 7.2 Lessons Learned
• 7.3 Takeaways and Future Work
Additional References ........................................................... .
Appendices .................................................................... .
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Abstract:
Samples of white portland cement were prepared using various methods and employing one of two non-traditional admixtures. Three samples were made containing rare-earth doped strontium aluminate. The first was mixed in accordance with ASTM G979 consisting of 10% phosphorescent powder by mass of cement. The second two samples contained increased concentrations of 30% and 50%. Measurable and usable phosphorescent glow was not successfully maintained in concrete with a 10% concentration, however, both of the samples with increased concentrations successfully phosphoresced. Additionally, a fine white portland cement mixture was poured over a network of light transmitting optical fibers. This sample successfully demonstrated the utility of translucent concrete and was able to transmit a significant and measurable amount of light from varying angles.
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Introduction:
Concrete is by and large the most produced and used construction material on earth. In 2017,
its global consumption amounted to 4.1 billion metric tonnes '. Its uses range from structural
building components to civil infrastructure to interior decor. Unfortunately, most concrete and cement production operations are highly energy and emissions intensive. As a result of its
ubiquitous utilization, it is estimated that the cement manufacturing industry accounts for between 5-10% of global carbon dioxide emissions. Concrete is the second most consumed
substance of Earth - after water - and as such, investigations into non-typical variations of concrete occupy a large area of materials research.' The development and advancements of
formulations such as porous, lightweight, high-strength, or low energy concretes dominate construction materials research for their obvious improvements to existing applications in pursuit of developing "green" concrete. Green concrete is defined as a concrete which uses waste
material as at least one of its components, or its production process does not lead to environmental destruction, or it has high performance and life cycle sustainability 3 This
project was not only an allempt to employ green concrete through the use of waste materials,
but also to approach sustainable concrete in a different way.
Adding a novel utility to an already ubiquitously used material is one of many ways to add to life
cycle sustainability. Our project's aim to create samples of phospholuminescent and translucent concrete gives rise to the idea that concrete can provide function beyond structure, and as such,
can be used in a wider array of applications.
Luminescent concrete is a relatively new and lillie-researched variation. Concrete possessing
luminous properties has the potential for applications in a variety of civil, structural, and design
areas. In addition to its potential for aesthetic and creative use, luminous concrete has applications in coating buildings, bike lanes, highways, interiors, and even swimming pools in
order to improve vehicular and pedestrian safety, as well as in reducing the need for energy
intensive street and building lighting.
One of the limiting factors of luminescent concrete is that traditional concrete is an opaque
material. Because light is not able to pass through the material, any photoactive material beyond the top veneer neither absorbs nor releases light energy. Researchers are investigating
ways to solve this problem in many ways ranging from adding clear aggregates and binding
agents to altering the crystalline structures formed when concrete cures.
1 US Geological Survey. (n.d.). Cement production globally and in the US from 2010 to 2017 (in million metric tons). In Statista - The Statistics Portal. Retrieved April 24, 2018, from hltps :llwww.statista.com/statistics/219343/ce me nt -production-worldwide/. 2 Rubenstein, Madeleine. "Emissions from the Cement Industry." State ofthe Planet, Earth Institute-Columbia University, 9 May 2012, bl ogs. e i. co I umbia. edu/201 2/05/09/em issi ons-from-the-ce ment -i nd ustry /. 3 Suhendro, Bambang. "Toward Green Concrete for Belter Sustainable Environment." Procedia Engineering, vol. 95, 27 Dec. 2014, pp. 305-320, doi10.1016/j.proeng.2014.12.190.
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Another closely related field of research has been investigating the possibility of creating translucent concrete. This material has the potential to drastically reduce the need for artificial light as it could transmit natural light through the faces of exterior walls or interior dividers. Though possible to create through the use of transparent aggregates and clear binding agents, translucent concrete has been most successfully achieved through the implementation of embedded optical fibers in concrete mixtures.
For our ENGR-090 Senior Design project, we experimented with cement mixtures containing a photoactive material which absorbs and subsequently emits light. Additionally, we created a concrete sample with an embedded matrix of optical fibers. We investigated mixture formulas and processes which are currently proposed and under patent by researchers in the field. By assessing how different methods of applying phosphorescent Strontium Aluminate affect the optical properties of the concrete, we determined the application method most suitable for a panel containing an optical fiber matrix.
In accordance to ABET General Criteria 3(c):
(c) an ability to design a system, component, or process to meet desired needs within realistic constraints such as economic, environmental, social, political, ethical, health and safety, manufacturability, and sustainability
This project builds on two existing areas of research in order to investigate new concrete materials. These materials have extensional applications to concrete exterior building walls, pedestrian safety infrastructure, and any number of other design applications where light emission or transmission is desired. In the future, a material like this could have the potential to reduce artificial light inside buildings, while also adding an aesthetic design appeal to interior fixtures and building elements.
Description of Materials:
Phosphorescent concrete'
Phosphorescent concrete provides a mechanism by which future cities could become less
dependant on electricity all the while increasing pedestrian and roadway safety. Developments
surrounding technologies which utilize phosphorescent materials mixed with cement could
illuminate walkways, buildings, and roadways at night.
The research and innovations around phosphorescent concrete are largely focused on
phosphorescent sealants, paints, and coatings that would protect existing concrete while adding
phosphorescent utility. Some of these materials can even be sourced from sustainable materials.
Purdue University's Andrew Wiese, Taylor Washington, Dr. Bernard Tao and Dr. Jason Weiss
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in their 2015 TRB paper, Assessing the Performance of Glow in the Dark Concrete, discuss their
soy-based, luminescent, "glow in the dark" (GITD) sealant that could be applied to the surface of
concrete. The sealant is a mixture of soy methyl ester polystyrene (SME-PS) and strontium
aluminate, a phosphorescent powder that luminesces after being excited by light. The authors
claim that it has important safety benefits, in addition to creating a more durable pavement.
"GITD sealant could be used to seal concrete for increased service life, to supplement
streetlights, and to increase the safety of the traveling public at night."4
The downside of sealant and application-based phosphorescent products is that they l.) do not
directly improve upon the sustainability of the concrete itself, and 2.) require separate
manufacturing, application, and maintenance. One way to resolve these issues, is to create a
concrete that, itself, luminesces. One researcher, Dr. Carlos Luis Rubio Avalos and researchers
in Mexico from the Michoacan University of San Nicolas de Hidalgo have created a new cement
mixture that tackles this problem. "By using additives, scientists are able to prevent the
formation of crystals that occur normally during the production of cement, creating a material
with a noncrystalline structure-similar to glass-that allows passage of light inside," Scientific
American wrote. "Varying the proportion of additives added while manufacturing the cement regulates both its luminescent intensity and color-so as not to dazzle drivers, if used on roads,
for example.'"
This ENGR-090 project employs the phosphorescent properties of the rare-earth mineral
strontium aluminate by incorporating it into a cementitious mix. This pigment additive works
well in that it is insoluble in water and not readily reactive with other chemical elements of
cement. By adding strontium aluminate to a cement mix, the resulting concrete is able to absorb
light energy during the day and then emit its own light for hours afterward. This emitted light is
practical for both safety and decorative purposes. Current research has found that adding
anywhere from 1-30% pigment to certain mixes has yielded success in producing visible
luminescence. These mixtures are usually applied as thin top layers of cement, sealants, or
epoxies coated over an existing concrete or asphalt layer. The powder can also be
homogeneously mixed into cement mixture, but is of course most effective along the outer layer
unless the material is not opaque 6
4 Wiese, Andrew S. Assessing the performance of sustainable and luminescent concrete sealers. Diss. Purdue University, 2015. 5 Carreno, Berta. "Glow-Hard: Luminous Cement Could Light Roads, Structures." Scientific American, 16 June 2016, www.scientificamerican.com/article/g low-ha rd-I umi nous-ceme nt-co uld-I ig ht -roads-structures/. 6 Gao, Fang, et al. "Improved Performance of Strontium Aluminate Luminous Coating on the Ceramic Surface." Journal of Physics: Conference Series, vol. 152, Jan. 2009, p. 012082., doi10 1088/1742-6596/152/11012082.
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Inducing phosphorescence often requires the presence of heavy atoms which can be toxic,
radioactive, or prohibitively expensive. A class of phosphorescent materials, called rare-earth
doped strontium aluminates, present unique opportunities for applications to cement. The
rare-earth minerals represent nonradioactive, heavy atoms with little toxicity. The key advantage
of this class of phosphorescent materials is that a close relative, undoped calcium aluminate, is
already a component of Portland cement. Contents of calcium aluminate vary with different
types of cement and mostly have an effect on the cure rate and early hardness of the cement.
Strontium aluminate has very limited solubility in water and the replacement of a rare-earth
metal cation for strontium further reduces the solubility. This substitution of the rare-earth doped
form of strontium aluminate for regular strontium aluminate should result in no other change in
the performance of the cement aside from inducing phosphorescence 7 These minerals are also
stable and continue to exhibit phosphorescence in alkaline conditions - like wet cement
whereas in many other materials phosphorescence is pH dependent. 8
Translucent concrete:
Another promising development in green concrete building materials is translucent concrete. By
interchanging ingredients of typical cement mixtures with transparent aggregates, or by
embedding optical fibers, concrete materials can be made to transmit light. Most typically a
combination of optical fibers and fine aggregates, translucent concrete can be precast into blocks
and panels. The miniscule size of the optical fibers means that they blend into concrete mixtures
homogeneously, much like fine aggregate.
Integrating optical fibers into concrete allows light to pass through the concrete from one side to
the other as light travels efficiently through the cores of each filament via internal reflection.
Around the core of each filament is a protective plastic layer that allows them to hold strong
even in the presence of outside forces and elements. Since the filaments are very thin, the
structure is still nearly 99% concrete and thus will not compromise its compressive strength.'
For our project, an 8" x 10" optical fiber network was embedded within a 10" x 14" concrete
panel. This involved using I mm fibers arranged in a 52 x 36 grid where one Imm filament was
placed every 5 mm.
7 "Glow in the Dark Powder." Techno Glow Inc., www.technoglowproducts.com/glow-i n-the-da rk-powde r -su pportl. 8 Kshatri, D. S., and A. Khare. "Optical Properties of Rare Earth Doped Strontium Aluminate (SAO) Phosphors: A Review." Optics and Spectroscopy, vol. 117, no. 5, Nov. 2014, pp. 769-783., doi1 0.1134/s0030400x1411 01 01. 9 1 mm filaments were used in a 52x36 grid. This accounts for roughly 1.6% of total volume in our 1 Ox14x2" panel.
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We will explore the effect of integrating both phosphorescent pigment additives and optical
fibers into concrete. This combination should create a strong concrete panel that both transmits
and emits light. During the day, the optical fibers will allow natural sunlight to pass through and
at night the phosphorescent pigment will glow.
Description of sand aggregate:
Glass Concrete Sand, acquired from Vitro Minerals, was used as a fine homogenous aggregate
made completely of recycled glass. Specifically, the MG-30 is glass made from recycled white
plate glass. This glass is without crystalline silica, label remnants, and post consumer debris, as
well as very low in lead content. See Appendix A for data provided by Vitro Minerals.
Description of optical filaments :l.!!
Single Strand Fiber Optic Filament(Polymethyl methacrylate Fluorinated polymer)
Fiber Diameter: I mm (1.25/32nd inches)
Numerical Aperture(NA) Acceptance angle/degree: 0.50/60
Available Temperature range: 40-70 C
Description of Glow Powder:
The glow powder implemented in our mix was a 50 micon green pigment Strontium Aluminate
Europium Dysprosium purchased from TechnoGlow.com. In light, the powder appears off-white
with a tint of green and becomes a vibrant glowing green in the darkness. The sand formula
allows for no absorption of liquid and thus does not dry out the concrete mix.
Material cost (Approximate):
Fiber optics: 180$
Glow Powder: 180$
Recycled Glass Powder: 60$
White Portland Type I Cement: 20$
Fiberglass Filament: 10$
10 http://lhefiberoplicslore.com/faq/fiber-specificalions-pholosl
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Experimental Procedure:
Design:
The phosphorescent panel was designed to be made using two different methods of applying the Strontium Aluminate powder. On one face of the panel, homogeneously mixed cement and
phosphorescent powder was poured. On the other side, a plain cement face was poured, but
using an equal amount of phosphorescent powder surface-applied onto the face after pouring. This design intended to assess whether or not a useful and/or comparable glow could be
achieved on the homogeneously mixed side as on the surface-applied face. If so, the same mix
design would then be used for our translucent panel. Initial mix design for phosphorescent cement was premised in accordance to ASTM standard G979. This standard indicates that pigment additives within cement mixtures should not exceed 10%."
A minimally viscous cement mixture was needed in order to pass through the 5-mm gaps
designed between the optical fibers within the translucent panel mold. However, the mix had to
remain strong enough to have utility. In order to create the finest mixture possible, only white portland cement, recycled waste glass sand, and fiberglass filament strands were used in the
mix. Because only glass sand was used as aggregate, a 2:1 sand: white portland cement with a
water content of approximately 30% was designed. High workability concrete with slump> 100 mm is typically used where reinforcing has tight spacing, and/or the concrete has to flow a great
distance."
The next design challenge was to create a form for our translucent panel. In order to maximize
the number of optical fibers embedded into our panel, it was necessary to keep in mind how the
cement mixture would pass through the mold, how the mold could be successfully removed after setting, and the time it would take to fabricate the mold.
Fabrication:
Preparing the phosphorescent concrete was fairly simple a straight forward. First the mold was built for the designed 1 Ox14" panel. This was done in a simple fashion by screwing together Y:;"
plywood boards that were plastic-wrapped and sealed water-tight. Next the mixture components
were weighed out to specified ratios and the two necessary cement mixtures were created -one with and one without strontium aluminate. Finally, the first Y:;" layer of mixed cement with
the powder was poured and allowed to congeal, but not set, for appx. 30 mins. Next, the rest of
our panel was poured and the phosphorescent powder was applied to the surface.
11 "This specification covers the basic requirement for colored and white pigments in powder form to be used as admixtures in concrete for the purpose of producing integrally colored concrete. Where the pigments are a constituent of a multicomponent admixture, this specification applies to the pigment constituent of the admixture." 12 Lyons, Arthur (2007). Materials for architects and builders. Butterworth-Heinemann.
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The panel was left to set for 24hrs. in a sealed and humid environment, and afterward transferred to a curing tank for several days. Once this panel was cured and the mold was removed, we visually examined the light emitted on both faces. Observationally, the face mixed with powder did not reveal an adequate glow. As a result, instead of mixing the remaining rations of glow powder into the cement for the fiber optic mold, the powder was used to test for required concentrations to achieve the desired result.
This was done by varying Strontium Aluminate powder concentrations in two standard test cylinders, 8 inches in height with 4 inch radius. The remaining 1.1 kg of Strontium Aluminate remaining was divided between the two to create concentrations of 30% and 50% volume by weight; i.e the 50% concentration sample was comprised of a 1:1 mix:powder ratio where .55-lbs of Strontium Aluminate was mixed with our previous cement mixture of sand and portland white cement. This mixture was then poured into the cylinder and allowed to sit for approximately 30 minutes before we filled the remainder of the cylinder with our standard 2:1 glass, cement mixture. The same process was repeated for the 30% sample, adjusting for the respective concentration.
The next step in fabrication was the most challenging and laborious portion of the project. In order to embed the optical fibers into the translucent panel, a mold was designed that used two Yo" acrylic sheets, each with a grid of 1872 (36x52) holes. These grids of holes were created using a vector drawing and printed out onto the acrylic sheets with a laser cutter. Due to the thickness of the sheets and the precision needed for the holes, each side took approximately 3 hours to cut. With the acrylic sheets prepared, the optical fibers were weaved through the laser cut holes in the acrylic. In order to have the mold be as water-tight as possible, each hole was cut marginally smaller than our 1 mm fibers ensuring that each pass was snug fit.
Initial observations from the phosphorescent panel that showed using a homogenous mixture with a reasonable amount of phosphorescent powder wasn't possible for creating a combined phosphorescent/translucent panel. The finaled pour into the translucent panel was done using cement made at the same ratios and proportions as the last, but with a slightly higher water content both to allow for needed flow and also to account for inevitable water loss in the mold. Pouring into the mold required a funnel and vibrating table ito facilitate passing the cement to through the grid of fibers. Again, after setting for 24 hrs and curing, the mold was carefully pried away and the optical fibers were sawed off flush to the concrete block.
Testing Design and Procedure:
Phosphorescent Samples:
The goal for testing the phosphorescent samples was to see how the light output of each sample varied over time. The samples were originally placed in a setting completely void of light for one day in order to completely discharge. They were then placed in direct sunlight outside on
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a minimally cloudy 75 degree day in Swarthmore, PA. They sat outside absorbing sunlight for exactly one hour before again being placed in a room completely void of light. Other than pure black light, sunlight is the most effective way to charge the material. Once placed in this completely dark room, a power meter was used to determine the power output of each sample at various distances over time. Measurements were taking at 1, 5, 10, 30, 60 and 90 minutes. At each time increment, power output was measured at 1, 6, and 12 inches from each sample. By 90 minutes, the samples all yielded a zero power output even though they continued to emit some visible light.
Translucent Sample:
The goal for testing the translucent panel was to test how much light was accepted through the panel. A 90 watt flood light was placed 2 inches behind the center of the panel. Using the same power meter as before, readings were again taken at 1, 6 and 12 inches from the panel. Next, the effect of changing the angle of the light behind the panel was tested. The light was raised 2 inches from its previous position, while the power meter location remained constant; this allowed for a 45 degree angle light to the center of the sample. Once the power output was again recorded at 1,6 and 12 inches the light was again raised to project light at 60 and 90 degrees.
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Experimental Results:
Figure 1 & 2. Phosphorescent Samples in the light and in the dark. From Right to left, 50%
additive, sprinkle face of panel, and 30% additive. (10% not shown)
24 (j) --<1l 3i: 18 0 c <1l Z ~
12 -:l a. -:l 0 .... 6 Q)
~ 0 a..
o 1
Phosphorescent Concrete -Power Output (at 1 inch) vs. Time
5 10 30
Time (Minutes)
Panel - 10% Mix Panel - Sprinkle Cylinder - 30% Cylinder - 50%
60 90
Figure 3. Shows power output vs. time for the Phosphorescent samples at a distance of 1 inch.
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14
Ul ..... ..... C1l 3i: 10.5 0 c: C1l Z ..... 7 :l Cl. ..... :l 0 .... 3.5 Q)
:s: 0 Il.
o 1
Phosphorescent Concrete -Power Output (at 6 inches) vs. Time
5 10 30
Time (Minutes)
Panel - 10% Mix Panel - Sprinkle Cylinder - 30% Cylinder - 50%
60 90
Figure 4. Shows power output vs. time for the Phosphorescent samples at a distance of 6 inches.
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Ul ..... ..... ~ 5.25 0 c: C1l Z ~
3.5 ..... :l Cl. ..... :l 0 .... 1.75 Q)
:s: 0 Il.
o 1
Phosphorescent Concrete -Power Output (at 12 inches) vs . Time
5 10 30
Panel - 10% Mix Panel - Sprinkle Cylinder - 30% Cylinder - 50%
60 90
Time (Minutes)
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Figure 5. Shows power output vs. time for the Phosphorescent samples at a distance of 1 inch
(Top), 6 inches (middle) and 12 inches (bottom).
Power Output Power Output 30% 50% (Panel 1 - mix) (Panel 1 - sprinkle) Cylinder Cylinder
Time: + +
1 Min
- 1 in 1 nw 13 nw 8 nw 22 nw
- 6 in o nw 9 nw 6 nw 13 nw
- 12 in o nw 7 nw 4nw 6 nw
5 Mins
- 1 in o nw 6 nw 3 nw 7n~ - 6 in o nw 4nw 2 nw 5 nw
- 12 in o nw 2 nw 1 nw 3n~ 10mins
- 1 in o nw 4nw 2 nw 4n~ - 6 in o nw 3 nw 1 nw 3 nw
- 12 in o nw 2 nw 1 nw 2n~ 30 Mins
- 1 in o nw 2 nw 1 nw 2n~ - 6 in o nw 1 nw o nw 1 nw
- 12 in o nw 1 nw o nw 1n~ 60 Mins
- 1 in o nw 1 nw =1 o nw 1 nW
- 6 in o nw o nw o nw OnW
- 12 in 0 0 0 onW]
90 Mins
- 1 in 0 0 0
l :~ - 6 in 0 0 0
- 12 in 0 0 0
Chart 1. Shows Power readings for Phosphorescent panel at incremental times and distances.
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400
(j)
~ 300
o "-.5:2 ~ ::: 200 ::::l 0. +-' ::::l o "-Q)
3: 100 o 0..
Figure 6. Final Translucent panel in front of90 watt light bulb.
Translucent Panel - Light Acceptance
o degrees 45 degrees 60 degrees 90 degrees
o ~------------------------------------------------~ 1 inch 6 inches 12 inches
Distance from Panel
Figure 7. Shows Light acceptance for Translucent panel as measurement distance from panel
increases for various angles.
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Initial Power of Source:
o Deg.
- 1 in
- 6 in
- 12 in
45 Deg.
- 1 in
- 6 in
- 12 in
60 Deg.
- 1 in
- 6 in
- 12 in
90 Deg.
- 1 in
- 6 in
- 12 in
90W
Power Output -Source Side:
30.5 uW
30 uW
Power Output -Panel Side:
390 uW
255 uW
140uW
49.5 uW
72uW
69 uW
29 uW
61 uW
64uW
1.7 uW
1.7 uW
1.6 uW
Percent Translucence
Chart 2. Shows Power readings for Translucent panel at various angles and distances.
Discussion of Results:
Translucent Panel:
The network of optical fibers successfully allowed for light to pass through the panel. Throughout the entire process of creating the panel only have one cable, of the total 1872, did
not work; giving us a 99.95% success rate on fabrication. This one cable was unsuccessful due
to a small air bubble that formed around it during the pour such that once the cement cured the cable was not properly embedded in the concrete and slid out.
Testing was done at multiple angles to simulate the different angles that light from the sun may pass through the fiber optics embedded in concrete. It is not uncommon for these translucent
panels to be used as walls as a way to let in natural light without windows. When the light was
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directly behind the panel, 0 degrees, the power output decreased slightly as the meter was moved away from the panel. For both 45 and 60 degrees, the power output actually increased as the meter was moved away from the panel. This is because ... The 90 degree tests showed approximately constant power outputs for all three distances.
Phosphorescent Panel:
As expected, when the concentration of Strontium Aluminate was increased, the brightness and duration of the emitted light also increased. The original 10% pigment additive mixture, based on ASTM standard, showed extremely low power output levels. This sample only yielded a small power reading at 1 inch from the face, 1 minute post sun exposure. This is something that was initially observed when the panel was first taken it out of the mold and exposed to sunlight. This weak emittance was part of what lead us to experiment with higher concentrations of Strontium Aluminate within the cement mixture. The 50% mixture was the brightest, followed by the sprinkled face of the panel and then the 30% mixture. After the initial reading, the 50% mixture and the sprinkled face of the panel seemed to yield very similar power outputs as time passed. So although the 50% mixture was the brightest on the initial reading, the sprinkled face of the panel was able to produce similar results while covering a larger surface area. Therefore it is clear that this method is confirmed to be the most effective use of the rare earth doped Aluminates. The problem with the sprinkling method is that much of the powder washed off when it was submerged in the curing tank. Therefore it was likely that the sprinkled panel face had significantly less powder to absorb and emit light after curing in the tank. Contrary to this, the mixed in powder left the edge smooth, clean and without powder loss. It would be interesting to observe the effect of mixing the phosphorescent powder in with the cement only on the top 1 mm or so of the panel face. This would ensure the highest amount of concentration at the face while also creating a surface that does not lose powder during curing and leaves the face clean and crisp. The problem with this is it makes the whole process much more complicated than using a homogeneous mixture. This would require multiple pours and is much less practical, especially for larger scale structures.
It is important to note that all three samples, not the 10% mixture, continues to emit a glow after the power output reading were at zero. Although this glow was not very bright it was still clearly visible in the all dark room. Furthermore, the power meter used for testing did not express values of brightness in lux or lumens; it did effectively give a standard measurement that allowed for direct comparison of each sample. It is also important to note that there were no performance tests done to evaluate the strength deterioration of increasing phosphorescent additive. Although the powder done act somewhat like a fine aggregate, it would not be surprising if the 50% mixture was less strong when subjected to pressure than say the 10% mixture.
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Conclusions:
This materials research experiment proved that both phosphorescent and translucent concrete
concepts are possible. With that being said, neither concept seems completely practical or
efficient with current technologies and methods. The quantity of Strontium Aluminate powder
that is needed to be homogeneously mixed with cement in order to produce usable glow is far too
high, becoming extremely expensive and likely compromising the concrete's strength. The
translucent panel required a highly labor intensive and slow process that makesmanual
production impractical and expensive.
Fortunately, these drawback are something that could potentially be overcome with the
implementation of new methods and technology. If continued research proves successful in
manipulating the microstructure of concrete as to increase opacity, it would likely allow for a
new high level of deep light absorption that would make mixing the phosphorescent additive
directly with the cement worthwhile and effective.
With the employment of modern machinery and automated fabrication, it would not be far
fetched to replace our manual processes with faster, more efficient ones. This would allow for
more economical and precise implementations of the discussed methods, or new methods all
together. These are a few of the possibilities that could take these concepts to a practical and
producible level. While these future steps are important, the achieved results of this project were
promising and give potential for new types of sustainable concrete.
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Additional References:
Fujita, Akihiro, et al. "THE OPTICAL CHARACTERISTIC OF LUMINESCENCE PAVEMENT MATERIAL." Proceedings AIC 2003 Bangkok (2003): 78.
PAVALARATHINAM, P. INVENTION OF FLUORESCENT PAVEMENT. Diss. ANNA UNIVERSITY OF TECHNOLOGY TIRUCHIRAPPALLI, 2012.
Nagdive, Neha R., and SHEKAR D. Bhole. "To evaluate properties of translucent concrete/mortar & their panels." International Journal of Research in Engineering & Technology 1.7 (2013): 23-30.
How to see through walls: Transparent concrete is encouraging architects to rethink how they design buildings. The Economist. Sept. 20, 2001. Available: http ://www.economist.com/node!77942l .
E. Allen & J. Iano. "Concrete Construction". Fundamentals of Building Construction: Materials and Methods , Fifth Edition. Hoboken, New Jersey, John Wiley & Sons Inc. 2009, Ch 13, pp. 515-551.
A. Goho. (Jan. 1, 2005). Concrete Nation: Bright future for ancient material. Science News, Vol. 167, No.1, p. 7. Available : http://www.concretewashout.com/downloads/Concrete _Nation_Science _News _ Online,_Jan._l, _2005.pdf
C. Hartman, Associated Press. (July 7, 2004). Seeing the Future of Construction Through Translucent Concrete. Seattle PI. Available: http://www.seattlepi.comlbusiness/article/Seeing-the-future-of-construction-through-1148906.ph p
Fonnulation for Obtaining a Translucent Concrete Mixture. US20090298972Al, US
Application.
G.ashok. "Perfomance Evaluation On Light Transmitting Concrete (Translucent Concrete )."
International Journal of Research in Engineering and Technology, vol. OS, no. 03, 2016, pp.
515-521., doi: 10. 1 5623!ijret.20 16.0503093.
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Appendix A:
Vitro '----'-'-''---' Min e r al s
ApPendjces:
www.glassfillers.com
Recycled Glass Concrete Sands Technical Data
Description: Vitro's CS and MG Glass Sands are functional fine ag.gregate materials made with uniform Qrain size di5tributions from 100% recyc led g lass: CS Glass from bottle glass and a greenish tan in color: and MG Glass from plate glass and white in color. CS and MG Glass Sands are free 01 crysta ll ine silica and provide a clean recycled sand for concrete. polymer concrete , mortars, and other similar systems. The products are very k7w in lead (Pb) content and free 01 label remnants and other post consumer debris .
Vitro provides a se~e wherein we willwork with the customer Ie incorporate the right g lass prod~t into their existing natural sands to allow them Ie get best properties relative Ie op~mal Fineness Modulus. FM (see next page). Contact your Vitro representat ive for more information.
Typical Chemical and Physical Properties ""T FOR Sf'£CIFICATION "'-"'POS[ S
Chflmi<:al Composition: SiD:! 70-80%: Nal 0 10-15%: CaO 9_13%; A110 l 1-5%; K20 <1%; Fe,DJ. <1 %; MgO <1%: So, <0,5%; TiO, <0, 1%; lOI <1%: Pb < 40 ppm
-. ,,. CS-30 .,- Ma-30 ,,~ CS.aO .'$ Test Mell>od
Sl*ifIc GIlI.lty " B " " " ,., " ,., ","Sl"M C127
By" O. nsi!y. tltn' " " " " " " " " ASl"M C127
09810p s iz • . m. sh , , w '" '" ~ '" '" Asm CI36
Sin "'1198. mm 2.4-4.7 1.7_3,4 0,21-0.60 0.30.-060 0 ,23-0.60 0.07-023 0 .07-0.18 O,07.{l , 18 ","sm CI36 0.23-0.60 ., 9.$-10 9 .$-10 10-10.5 10-10 .5 10-10.5 10-11 10·1 1 10-11 AFS 113-875
""', "'~ ""'" ofl'...n~ 'u~r· "'"' cfl'whiJe ""'" "'"' while Hardness " " " " "
,., " " Mohs Seale
F ... molstu .. , % <0.5 <0,5 " 0.5 <0 ,5 ~, <0,5 <0.5 <0,5 ","sm C566
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Appendix B:
~ID~ Oeaignatlon: C 979 - 99 .... 0IeAN SOCI(TV '011 , .. , .... """ ..... TEIOJAl.
, .. __ Dr ,_C. t. ' .. ""om "-_ ... _-" .. , .. - "-.. ,,, Standard Specification for Pigments for Integrally Colored Concrete 1
n.._" __ .... ___ C919, .... __ If_ ........ __ _.... .... ,,..,ot ..... ..so,:.-Of • ...... ,_ot .... _ .... ~ otlM< .... _ A __ .... "id_.--. .... r- 01 1M< ,_'.II A
___ "" tpOdoo {.J """'_ .. _>&1 tIwp ""'" .... 1M< "" .... _ Of ,_"AI
1.4 The maxim1llll prescribed dosage rate of a pigment. established in accordance with ].7. shaH be: equal 10 or less than 10 mass % of Cc:metlt. Wben a combinalion ofpigruellts is used 10 produce the desired color and color inlensity. the 10lal dosage nile of all pigments combined shaH IlOl excc:c:d any o f the individual maximum dosage niles of the componelll pismc:nts.
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