Light Transmitting Concrete or Transparent Concrete

Seminar Report-2015 Light Transmitting Concrete
B.Tech, Department Of Civil Engineering 1 T.K.M Institute Of Technology
1. INTRODUCTION
Due to economic development and space utilization requirements, high-
rise buildings and skyscrapers are mostly built downtown in metropolitan areas
around the world, especially countries with great population. This arises one of the
problem in deriving natural light in building, due to obstruction of nearby
structures. Due to this problem use of artificial sources for illumination of
building is increased by great amount. So it is very essential to reduce the artificial
light consumption in structure.
It is considered to be one of the best sensor materials available and has
been used widely since the 1990s. Hungarian architect, Aron Losonczi, first
introduced the idea of light transmitting concrete in 2001 and then successfully
produced the first transparent concrete block in 2003, named LiTraCon. However
his light transmitting concrete did not have smart sensing properties. Light
transmitting concrete also known as transparent concrete is a novel construction
material manufactured with optical fiber by drilling through the cement and
mortar in order to utilize the light guiding ability of optical fiber. The main
purpose was to use sunlight as a light source in order to reduce the power
consumption of illumination.
Light transmitting concrete are available as prefabricated blocks / panels.
Litracon rooms will be brightened and proximal objects situated on the brighter
side of a transparent wall will be revealed as silhouettes on the other side. Though
the optical fibers compose only 4% of the concrete, some light is transmitted
because of their parallel arrangement in a matrix between to the two outer surfaces
of each block. Load-bearing structures can also be built from these blocks, since
optical fibers have no negative effect on the strength of the concrete. The blocks
come in various sizes and option of embedded heat-isolation. Since not everyone
appreciates the look of exposed concrete.

2. PRINCIPLE
Transparent concrete or translucent concrete is work based on “Nano-
Optics”. Optical fibers passes as much light when tiny slits are placed directly on
top of each other as when they are staggered. It is because optical fibers in the
concrete act like the slits and carry the light across throughout the concrete.
Thousands of optical glass fibers form a matrix and run parallel to each
other between the two main surfaces of each block. The fibers mingle in the
concrete because of their insignificant size and they become a structural
component as a kind of modest aggregate. The blocks can be produced in various
sizes and with embedded heat-isolation.
Light transmitting concrete is a combination of optical fibers and fine
concrete. It can be produced as prefabricated building blocks and panels. Due to
the small size of the fibers, they blend into concrete becoming a component of the
material like small pieces of aggregate. By arranging high numerical aperture
Plastic Optical Fibers (POF) or big diameter glass optical fiber into concrete, it
transmits light so effectively that there is virtually no loss of light conducted
through the fibers.
The glass fibers lead light by points between the two sides of the blocks.
Because of their parallel position, the light-information on the brighter side of
such a wall appears unchanged on the darker side. The most interesting form of
this phenomenon is probably the sharp display of shadows on the opposing side of
the wall. Moreover, the color of the light also remains the same.

3. MATERIALS
3.1. OPTICAL FIBERS
An optical fiber is a flexible, transparent fiber made of glass (silica) or
plastic to a diameter slightly thicker than that of a human hair. Optical fibers are
used most often as a means to transmit light between the two ends of the fiber. An
optical fiber consists of a core, a cladding layer and a buffer coating. Fig 3.1
shows a typical structure of optic fiber.
Fig 3.1: Structure of optical fiber
Core –The core is a cylindrical rod of dielectric material. Dielectric material
conducts no electricity. Light propagates mainly along the core of the fiber. The
core is generally made of glass. And in another way we can say it is a central tube
of very thin size made up of optically transparent dielectric medium and carries
the light form transmitter to receiver. The core diameter can vary from about 5µm
to 100 µm.
Cladding – It is the outer optical material surrounding the core having reflecting
index lower than core. It helps to keep the light within the core throughout the
phenomena of total internal reflection. Even though light will propagate along the

fiber core without the layer of cladding material, the cladding does perform some
necessary functions. The index of refraction of the cladding material is less than
that of the core material. The cladding is generally made of glass or plastic.
The cladding performs the following functions:
 Reduces loss of light from the core into the surrounding air
 Reduces scattering loss at the surface of the core
 Protects the fiber from absorbing surface contaminants
 Adds mechanical strength
Buffer Coating – plastic coating that protects the fiber made of silicon rubber. The
typical diameter of fiber after coating is 250-300 µm. For extra protection, the
cladding is enclosed in an additional layer called the buffer coating. The buffer
coating is a layer of material used to protect an optical fiber from physical
damage. The material used for a buffer is a type of plastic.
The buffer is elastic in nature and prevents abrasions. The buffer also
prevents the optical fiber from scattering losses caused by micro bends. Micro
bends occur when an optical fiber is placed on a rough and distorted surface.
3.1.1. Types of optical fiber
There are three basic types of optical fibers.
3.1.1.1. Multi-mode graded-index fiber
In graded index fiber there are many changes in the refractive index with
larger values towards the center, as light travels faster in a lower index of
refraction. So, the farther the light is from the center axis, the greater is its speed.
Each layer of the core refracts the light. Instead of being sharply reflected as it is
in a step index fiber, the light is now bent or continuously refracted in an almost
sinusoidal pattern. Those rays that follow the longest path by travelling near the
outside of the core have a faster average velocity. The light travelling near the
center of the core has the slowest average velocity. As a result all rays tend to
reach the end of the fiber at the same time. That causes the end travel time of
different rays to be nearly equal, even though they travel different paths.

3.1.1.2. Multi-mode step-index fiber
This fiber is called "Step Index" because the refractive index changes
abruptly from cladding to core. The cladding has a refractive index somewhat
lower than the refractive index of the core glass. As a result, all rays within a
certain angle will be totally reflected at the core-cladding boundary. Rays striking
the boundary at angles greater than the critical angle will be partially reflected and
partially transmitted out through the boundary. After many such bounces the
energy in these rays will be lost from the fiber. The paths along which the rays
(modes) of this step index fiber travel differ, depending on their angles relative to
the axis.
3.1.1.3. Single-mode step-index fiber
Another way to reduce modal dispersion is to reduce the core's diameter,
until the fiber only propagates one mode efficiently. The single mode fiber has an
exceedingly small core diameter of only 5 to 10 m. Standard cladding diameter
is 125 m. Since this fiber carries only one mode, model dispersion does not
exists.
A multimode fiber can propagate hundreds of light modes at one time while
single-mode fibers only propagate one mode as shown below.
Fig 3.2: Types of Fiber

3.1.2. Total internal reflection
Fig 3.3: Schematic representation of total internal reflection
When light traveling in an optically dense medium hits a boundary at a
steep angle (larger than the critical angle for the boundary), the light is completely
reflected. This is called total internal reflection. The process of total internal
reflection is shown in fig:3.3. This effect is used in optical fibers to confine light
in the core. Light travels through the fiber core, bouncing back and forth off the
boundary between the core and cladding. Because the light must strike the
boundary with an angle greater than the critical angle, only light that enters the
fiber within a certain range of angles can travel down the fiber without leaking
out. This range of angles is called the acceptance cone of the fiber. The size of this
acceptance cone is a function of the refractive index difference between the fiber’s
core and cladding.
3.1.3. Benefits of optical fiber
Following are the benefits of optical fiber:
 It can be bend in different shapes.
 It has a less bending radius.
 It is resilient to damage.
 It is abuse than glass.
 Cutting, wiring, bonding, connecting and processes are easier.
 It does not produce radiation.

 It is immune to radio magnetic interference, radio frequency interference
and noise.
3.2. CEMENT
As the optical fiber is only responsible for transmission of light, there is no
special cement required. So, ordinary Portland cement is used for transparent
concrete.
3.3. SAND
Sand is a naturally occurring granular material composed of finely divided
rock and mineral particles. The composition of sand is highly variable, usually in
the form of quartz. Sand particles should pass through 1.18 mm sieve. The sand
used is the normal sand. It should be free from impurities such as vegetation and
gravels
3.4. WATER
Water is the key ingredient, which when mixed with cement, forms a paste
that binds the aggregate together. The water needs to be pure in order to prevent
side reactions from occurring which may weaken the concrete, the role of water is
important because the water to cement ratio is the most critical factor in the
production of "perfect” concrete. It should be of drinking water quality. That is it
should be free from all impurities.

4. MANUFACTURING PROCESS
The manufacturing process of transparent concrete is almost same as
regular concrete. Only optical fibers are spread throughout the aggregate and
cement mix. There are different methods for the installation of optical fiber in
concrete.
One method is that, small layers of the concrete are poured on top of each
other and infused with the fibers and is then connected. Thousands of strands of
optical fibers are cast into concrete to transmit light, either natural or artificial.
Light-transmitting concrete is produced by adding 4% to 5% optical fibers by
volume into the concrete mixture. The concrete mixture is made from fine
materials only it does not contain coarse aggregate. Thickness of the optical fibers
can be varied between 2 μm and 2 mm to suit the particular requirements of light
transmission. Originally, the fiber filaments were placed individually in the
concrete, making production time-consuming and costly.
Newer, semi-automatic production processes use woven fiber fabric
instead of single filaments. Fabric and concrete are alternately inserted into
moulds at intervals of approximately 2 mm to 5 mm. Smaller or thinner layers
allow an increased amount of light to pass through the concrete. Following
casting, the material is cut into panels or blocks of the specified thickness and the
surface is then typically polished, resulting in finishes ranging from semi-gloss to
high-gloss.
In another method, the first step is to make a mould for the prototype block
using tin. The tin is made into a mould of the desired shape, like a cuboid with the
top end open. Many holes are punched on the opposite walls of the cuboids. The
optical fibers have to be run through these holes from one end to the other and
then concrete is made to set in it with the fibers inside. What happens here is that
the light falling on one side of the block gets transferred to the other side through
these many optical fibers running from one end to the other.

This is the trickiest part of the construction, passing each thin fiber through
the tiny holes of one perforated sheet to another one. This is also an integral part
of the process as the whole idea of transparency comes from these fibers. The
light is transferred from one end to another end through these, as mentioned
earlier. So much care has been taking in this process. The next step is to cast the
mortar over these fibers placed in the tin mould as shown in the fig: 4.1. The
concrete then undergoes a curing process. The excess fibers running out of the
block are cut off and slightly polished. The modeling of transparent concrete
block is complete.
Fig 4.1: Schematic layout of a moulded block with the fixed fiber composites within the
framework

5. PROPERTIES
The properties of light transmitting concrete are determined by conducting
various experiments like compressive strength test and flexural strength. A typical
transparent concrete block is shown in fig: 5.1.
Fig 5.1: Transparent concrete block
5.1. COMPRESSIVE STRENGTH:
By definition, the compressive strength of a material is that value of
uniaxial compressive stress reached when the material fails completely. The
compressive strength is usually obtained experimentally by means of a
compressive test. The compressive strength of the concrete is determined by cast
the cubes of size 150mm x150mm x 150mm.
Compressive strength = load/area.
The compressive strength of the conventional concrete and light
transmitting concrete in 7, 14 and 28 days is shown in figure: 5.2. Mix proportions
are as follows:

Cement – 360 kg
Sand – 560 kg
Fiber – 4.5 kg
Water – 190 lit
Fig 5.2: Compressive strength of concrete (Source: P.M.Shanmugavadivu, et.al; 2014)
The compressive strength of light transmitting concrete was compared
with ordinary plain cement concrete and result showed that the compressive
strength of litracon was similar to that of ordinary plain cement concrete. Hence it
is suitable for load bearing structures also.
5.2. FLEXURAL STRENGTH:
The flexural strength of the concrete is determined by conducting the test
on prism by two points loading.
Flexural strength = Pl/bd2
Where,
P – Load

l – Length of the specimen
b – Width of the prism
d – Depth of the prism
The flexural strength of the conventional concrete and light transmitting
concrete having mix proportion as above in 7, 14 and 28 days is shown in figure
5.3.
Fig 5.3: Flexural strength of concrete (Source: P.M.Shanmugavadivu, et.al; 2014)
The flexural strength result of decorative concrete are correlated with
results of ordinary plain cement concrete. The results evidently show that the
performance of litracon based on the strength aspect is also considerably high.
Hence the application of optical fiber will make the concrete decorative as well as
can make the concrete structural efficient.
Thus the study concludes that the transparency of light is possible in
concrete without affecting its compressive strength, as the optical fibers act as
fiber reinforcement thereby enhancing the strength and also enhances appearance.

5.3. MATERIAL PERFORMANCE:
 Concrete retains its strength
 High density top layer concrete
 Infused with optical fibers
 Frost and de-icing salt resistant.
 Fire protection.
 Highest UV resistance.
Some other properties of light transmitting concrete are:
 Permits the passage of light through the set concrete, permitting colors,
shapes and outlines to be seen through it.
 Having Compressive strength-50-220 N/mm2
 Having maximum water absorption of 0.35%.
 Having a maximum oxygen index of 25%.
 Having a thermal conductivity of 0.21 W/m °C.
 Having a flexural Strength of 7.7 N/mm2
 Having an elastic limit greater than 60 MPa.
 Having a Density from 2100 to 2400 kg/m3
 Having a Young's Modulus from 2750 MPa to 3450 MPa
 From its characteristics and composition, can be a conductor of electricity,
dispensing with interior.
 From its mechanical and optical characteristics, can be used for purposes
that are both architectural and aesthetic, and also structural and under
conditions of service equal to and even different from those of a traditional
concrete.

6. ADVANTAGES
Following are the advantages of light transmitting concrete:
 It has very good architectural properties for giving good aesthetical
view to the building.
 Translucent concrete can be used at the place where light is not able to
come properly.
 Energy saving can be done by utilization of translucent concrete in
building.
 Totally environment friendly because of its light transmitting
characteristics, so energy consumption can be reduced.
 When a solid wall is imbued with the ability to transmit light, it means
that a home can use fewer lights in their house during daylight hours.

7. APPLICATION
Various applications of transparent concrete are:
7.1. ILLUMINATION OF WALL
Transparent Concrete can be used as building material for interior and
exterior walls. If sunshine illuminates the wall structure, then eastern or western
placement is recommended; the rays of the rising or setting sun will hit the optical
glass fibers in a lower angle and the intensity of the light will be bigger. Besides
the traditional applications of a wall, the light transmitting concrete can also be
used as wall covering illuminated from the back.Fig:7.1 shows illuminated walls
using light transmitting concrete.
Fig 7.1:Walls illuminated by transparent concrete
7.2. PAVEMENT
Light transmitting concrete can be used as flooring a passable surface
illuminated from below. During the day it looks like typical concrete pavement
but at sunset the paving blocks begin to shine and in different colors. Fig:7.2
shows the pavement illuminated by transparent concrete.

Fig 7.2: Pavement illuminated by transparent concrete
7.3. DESIGN
The building units are versatile and can be used in many areas of design.
We can also create a logo with colorful figures, inscriptions, and pictures and can
used for beautification purpose.Fig:7.3 shows illuminated litracon panels.
Fig 7.3: Transparent concrete panels

7.4. RECEPTION DESK
Using transparent concrete reception desks can be light up in the front and
the sides.Fig:7.4 shows reception desk light up by transparent concrete.
Fig 7.4: Reception Desk made of transparent concrete
7.5. LIGHTING FIXTURE
The transparent concrete cube is, without a doubt, a great conversation
piece. The new cube line consists of four identical pieces of concrete and, due to
its special geometry; the pieces form a stable structure without fixing them
together. Fig 7.5 show lamps made of litracon.
Fig 7.5: Lamps made of litracon

7.6. STAIRS
Litracon can also be used in stairs. With impact lighting of linear LED
fixtures translucent concrete can be used in horizontal and vertical applications
such as feature stairs, walls, flooring, tables and counter tops.Fig:7.6 shows
transparent concrete stairs.
Fig 7.6: Transparent concrete stairs
It can be also applicable at:
 Translucent concrete blocks inserted on front doors or walls next to it
allow the residents to see when there is a person standing outside.Fig:7.9
shows silhouette of a person standing outside the transparent concrete
wall.
Fig 7.9: Silhouette of person standing outside

 Translucent concrete walls on restaurants, clubs, and other social
establishments help see how many people are actually inside it.
Transparent concrete walls in an office can be seen in fig:7.10.
Fig 7.10: Transparent concrete walls in an office
 Ceilings of large corporate buildings with translucent concrete would help
reduce a great deal of lighting costs during day time.Fig:7.11 shows
transparent concrete ceiling.
Fig 7.11: Transparent concrete ceiling

 Speed bumps in parking lots and highways can use translucent concrete
blocks with a light source beneath or reflecting from other vehicles/sources
help in navigation very effectively. Even lane markers in highways can use
this material to light up the roads.Fig:7.12 shows highway marked with
transparent concrete.
Fig 7.12: Highway marked with transparent concrete
 Sidewalks with translucent concrete fitted with a single light source
beneath would add a lot to the scenic beauty as well as safety and also
encourage walking or foot travel during night times. Iluminated panels can
be seen in fig:7.13.
Fig 7.13: Transparent concrete panel

 Translucent concrete blocks incorporated in inner walls help during times
of power cuts at night leading to a great deal of safety. Similarly for
subways and airports etc., this translucent concrete blocks would add to
the visibility. Transparent concrete wall can be seen in fig:7.14.
Fig 7.14: Exterior translucent wall
 Translucent concrete blocks can be made in desired shapes and used as
decorative materials like bookshelves and sunshades, tables and statues. A
wash stand made of light transmitting concrete can be seen in fig: 7.15.
Fig 7.15: Wash stand made of transparent concrete

 They can also be placed as random designs on security walls which also
enhance security giving the resident a hazy view of the perimeter. Fig 7.16
shows the silhouette of a person through a transparent concrete wall.
Fig 7.16: Transparent concrete wall
 Places like schools, museums and prison cells outer walls can find
translucent walls very useful as they add safety as well as security and
supervision.

8. A FEW EXAMPLES
8.1. EUROPEAN GATE
European gate is an artistic installation which was designed to mark the
celebration of Hungary joining the European Union (EU), located at the public
entrance of Fortress Monostorin the Hungarian town of Komarom. This is one of
the most impressive pieces of art conjugating visual lighting display as well as
artistic using translucent concrete. The sun illuminates the 37.6ft large Litracon
piece of the statue in the mornings and late afternoons, and by night an even more
impressive view can be seen because of the embedded light sources. Day and
night view of European gate is shown in fig: 8.1.
Fig 8.1:Day and night view of European gate
8.2. CELLA SEPTICHORA VISITOR CENTRE
The 2 tons heavy Litracon door serves as the main entrance of the Visitors
Centre. It was made out of 48pcs of 10cm thick blocks. The blocks are in steel
frame to be able to move the structure. On daytime, one can see the shadows of
the pedestrians and the surrounding trees from inside. By night, the door is

illuminated from inside. Day view and night view of litracon door is shown in fig
8.3 and fig: 8.4.
Fig 8.3: Day view of litracon door from inside
Fig 8.4: Night view of litracon door

8.3. MONTBLANC BOUTIQUE, TOKYO, JAPAN
Litracon blocks (600x300x30mm) were used to create a wall that works as
a free-standing sculptural element in this flagship boutique for Montblanc. As
much as 30 Esq. of white Litracon was used. The illumination ensures that light
and shadow constantly do a dance on the wall.Fig:8.5 shows a transparent wall
transmitting sunlight to interior of the montblanc boutique.
Fig 8.5: Montblanc boutique
8.4. NEW HEADQUARTERS OF BANK OF GEORGIA
The office building is characterized by an amazing architecture and has
been the headquarter of the Georgian ministry for highway engineering before
becoming headquarter of Bank of Georgia, Tbilisi, with a total area of 10.960
square meters. It consists of five horizontal two-storied building parts which are
arranged like stacks. Thousands of embedded optical fibers are channeling the
light through the translucent concrete of wall and counter cladding. Walls, walks,
receptions, offices and consultation desks are shinning and glowing from within.
An office room of bank can be seen in fig: 8.6.

Fig 8.6: New headquarters of bank of Georgia

9. DISADVANTAGES
Following are the disadvantages of transparent concrete:
 The main disadvantage is that these concrete has a very high initial cost
because of the optical fibers.
 Casting of translucent concrete block is difficult for the labor, so special
skilled person is required.

10. CONCLUSIONS
A transparent concrete is aesthetically pleasing. Optical fiber based
transparent concrete could be regarded as an art which could be used in museums
and specific exhibitions rather than just a construction material. Although ease of
construction is to be compromised, the material is bound to be accepted
universally due to its advantages. With the concept of green technology catching
up, electrical supply, being supplemented by natural sources, it becomes
absolutely necessary to utilize the natural resource. Although litracon has yet to be
made available for commercial use, it has already been suggested that buildings
made with the material could save electricity that would otherwise be required for
daytime lighting. Moreover, this light transmitting concrete can be utilized in the
production of special types of home furniture. In future, the cost of light
transmitting concrete is expected to decrease with the advancement in technology,
manufacturers and as well as the users. Translucent concrete is the future. It is the
smart way of optimizing and utilizing light, a smart way of living.

REFERENCE
1) Basma F. Bashbash, Roaa M. Hajrus, Doaa F. Wafi, Mamoun A. Alqedra
“Basics of Light Transmitting Concrete”: Global Advanced Research
Journal of Engineering, Technology and Innovation (ISSN: 2315-5124)
Vol. 2(3) pp. 076-083, March, 2013
2) B. Sawant, R. V. Jugdar, S. G. Sawant, “Light Transmitting Concrete by
using Optical Fibre”:International Journal of Inventive Engineering and
Sciences (IJIES)ISSN: 2319–9598, Volume-3 Issue-1, December 2014
3) Bhavin K. Kashiyani, Varsha Raina, Jayeshkumar Pitroda, Dr. Bhavnaben
K. Shah. “A Study on Transparent Concrete”: A Novel Architectural
Material to Explore Construction Sector: International Journal of
Engineering and Innovative Technology (IJEIT),Volume 2, Issue 8,
February 2013
4) M.N.V.Padma Bhushan, D.Johnson, Md. Afzal Basheer Pasha And Ms. K.
Prasanthi. “Optical Fibres in the Modeling of Translucent Concrete
Blocks”: International Journal of Engineering Research and Applications
(IJERA), Vol. 3, Issue 3, May-Jun 2013, pp.013-017
5) Pacific science review, vol 15,no 1,2013,pp.51-55
6) Patil Gaurao S, Patil Swapnal V. “Light Transmitting Concrete- A New
Innovation”: International Journal of Engineering Research and General
Science, Volume 3, Issue 2, Part 2, March-April, 2015,ISSN 2091-2730
7) P.M.Shanmugavadivu, V. Scinduja, T.Sarathivelan, C.V Shudesamithronn,
“An Experimental Study On Light Transmitting Concrete”: IJRET:
International Journal of Research in Engineering and Technology,
Volume: 03, Special Issue: 11, Jun-2014,
8) Soumyajit Paul, Avik Dutta.“Tranclucent concrete” :International Journal
of Scientific and Research Publications, Volume 3, Issue 10, October 2013
9) www.inventorspot.com

Light Transmitting Concrete or Transparent Concrete

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Viewers also liked

Viewers also liked (19)

Similar to Light Transmitting Concrete or Transparent Concrete

Similar to Light Transmitting Concrete or Transparent Concrete (20)

Recently uploaded

Recently uploaded (20)

Light Transmitting Concrete or Transparent Concrete