EXPERIMENTAL STUDY OF TRANSPARENT CONCRETE

PRESENTED BY:

K.S.SABHAPATHYFINAL YEAR (CIVIL)RCETmadurai

ABSTRACT

Building energy saving and safe evaluation for engineering structures have obtained the worldwide attention. It is much of importance for developing a new kind of building material, which can integrate green energy saving with self-sensing properties of functional material. In this paper, based on the excellent properties of light guiding and elasto-optic effect of optical fiber, a novel smart transparent concrete is researched by arranging the optical fibers into the concrete. To evaluate the effectiveness of the smart transparent concrete, the light guiding based on white light test, long-term durability based on freezing and thawing test and chloride ion penetration test, and self-sensing property based on stress elasto-optic effect test are made respectively. The experiments results show that the smart transparent concrete has good transparency, mechanical and self-sensing properties.

INTRODUCTION

With the economic growth and science-technology development, more and more large-scale civil engineering structures such as tall buildings, underground buildings and landmark buildings and so on are built around the world. While the economic growth is a kind of extensive growth: high input, high consumption and high pollution, for that the energy saving technology is low, especially in developing countries. The brightness of indoor environment is entirely maintained by artificial lighting, which has consumed a large number of resources. Moreover civil engineering structures always suffer from external environmental effects, economic loss and casualties are serious once damaged. And now, building energy saving and building safety have been attracted much attention. Many large span bridges and new landmark buildings have been successfully implemented structural health monitoring systems. Optical fiber sensors such as fiber Bragg Grating, Brillouin distributed sensors and plastic optical fiber sensors have been widely used for the in situ monitoring of major projects.

WHAT IS OPTICAL FIBERS….. ??? & WHAT IS ITS IMPACT IN CIVIL ENGINEERING ……???

OPTICAL FIBER• An optical fiber is a hair thin

cylindrical fiber of glass or any transparent dielectric medium.

• The fiber which are used for optical communication are wave guides made of transparent dielectrics.

• Its function is to guide visible

and infrared light over long distances.

STRUCTURE

Core – 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 5um to 100 um.

Cladding – 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.

Buffer Coating – plastic coating that protects

the fiber made of silicon rubber. The typical diameter of fiber after coating is 250-300 um.

WORKING PRINCIPLETotal Internal Reflection

• When a ray of light travels from a denser to a rarer medium such that the angle of incidence is greater than the critical angle, the ray reflects back into the same medium this phenomena is called total internal reflection.

• In the optical fiber the rays undergo repeated total number of reflections until it emerges out of the other end of the fiber, even if the fiber is bent.

The arrow and the bent pencil

TOTAL INTERNAL REFLECTION IN FIBER

The life of fiber is longer than copper wire

Handling and installation costs of optical fiber is very nominal

It is unaffected with electromagnetic interference

Attenuation in optical fiber is lower than coaxial cable or twisted pair.

There is no necessity of additional equipment for protecting against grounding and voltage problems.

As it does not radiates energy any antenna or detector cannot detects it hence provides signal security

ADVANTAGES OF OPTICAL FIBER COMMUNICATION

APPLICATION

• Optical fiber have wider range of application in almost all field, some are been specified below

• In telecommunication field• In space applications• Broadband applications• Computer applications industrial applications • Mining applications• In medical applications• In military applications etc.

OPTICAL FIBER IN TRANSPARENT CONCRETE

• Translucent concrete is a concrete based building material having light-Transmissive property.

• Light-Transmissive property is mainly due to uniform distribution of high numerical aperture Plastic Optical Fibres (POF) throughout its body.

• Hence it is also known to be transparent concrete, LiTraCon.

MATERIAL USED FOR TRANSLUCENT CONCRETE• The two basic materials used

for making transparent concrete

Fine concrete Optical fibres• Fine concrete: Consists of

cement and fine aggregate such as sand.

• Optical fibres: There are 3 kinds

Multimode graded-index fibre

Multimode step-index fibre Single-mode step-index

fibres.

PRINCIPLE• Translucent concrete works Based on “Nano-

Optics”.• These fibres passes as much light when tiny slits

are placed directly on top of each other. Hence optical fibers in the concrete act like the slits and carry the light across throughout the concrete.

MANUFACTURING PROCESS• The manufacturing

process of transparent concrete is almost same as regular concrete.

• Small layers of the concrete are poured into the mould and on top of each layers, a layer of fibres is infused.

• Fabric and concrete are alternately inserted into moulds at intervals of approximately 2 mm to 5mm.

MANUFACTURING PROCESS• Light-transmitting concrete is

produced by adding 4% to 5% optical fibres by volume into the concrete mixture.

• The concrete mixture is made from fine materials and does not contain coarse aggregate.

• Thousands of strands of optical fibres are cast into concrete to transmit light

• Smaller or thinner layers allow an increased amount of light to pass through the concrete.

EXPERIMENTAL SAMPLE MOULD

• We designed our sample mould with simple plastic tray.

• used optical fiber cable at size of (100 um)

• due to small thickness of optical cable we are using fine concrete (without coarse aggregate)

• making a ratio of 1:2 for mixing

• clay is used to withstand optical cables for support.

WORKING METHOD• choosing a desire

mould.• make a needed design.• attach clay on the

bottom of the mould.• induce optical fiber

cables at desired shape.• after induced pour fine

concrete at its approximate ratio.

• set to dry and allow to curing.

OUTPUT• We get out transparent concrete in desired shape.

EXPERIMENTS OF SMART TRANSPARENT CONCRETE

• Evaluation Method of Light Guiding of Smart Transparent Concrete :

There are many performance indicators to be considered whether the transparency of material is good or not, such as transmittance, haze, refractive index, birefringence and dispersion and so on. In this paper, the transmittance is used to appraisal the light guiding of smart transparent concrete. For the homogeneous materials such as homogeneous glass or LiTraCon above mentioned, their transmittance can be directly calculated by the ratio of the incident energy and transmission energy of light expressed as following equation:

Light Guiding Experiment of Smart Transparent Concrete

Newport 835 Optical Power Meter Measuring area of the concrete in the Light Guiding Experiment

COMPRESSION TEST FOR MOULD

PROCESS OF FREEZING & HEATING

EXPECTED STRENGTH

PRODUCT LITRACON - LIGHT TRANSMITTING CONCRETE

   

Form Prefabricated blocks    

Ingredients 100% concrete, 4% optical fibre

   

Density 2100-2400 Kg/m3    

Block size 150mm x 80mm    

Thickness 25-50mm    

Colour Grey    Fibre distribution Organic    

Finished Polished    

Compressive strength 31.44 N/mm2    

APPLICATIONS• In furniture for the

decorative and aesthetic purpose.

• Light sidewalks at night. • Increasing visibility in

dark subway stations. • Lighting indoor fire

escapes, in the event of a power failure.

• Illuminating speed bumps on roadways at night.

CONCLUSION• A novel architectural material called transparent

concrete can be developed by adding optical fibre or large diameter glass fibre in the concrete mixture. The transparent concrete has good light guiding property and the ratio of optical fibre volume to concrete is proportion to transmission. The transparent concrete not looses the strength parameter when compared to regular concrete and also it has very vital property for the aesthetical point of view. It can be used for the best architectural appearance of the building. Also used where the light cannot reach with appropriate intensity. This new kind of building material can integrate the concept of green energy saving with the usage self-sensing properties of functional materials.

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“TRANSPARENT CONCRETE IS DEFINITELY THE PRESENT AND THE

FUTURE”