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Bhania Faizal13008072003

SPECIAL TYPES OF CONCRETES

Guided By :Dr.A.K.VermaDr.Darshana Bhatt

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BIO CONCRETE

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WHAT IS BIO CONCRETE•Its is a special type of concrete invented by a group of microbiology researchers under the head of Henk Jonkers.

•Bio concrete is also called as BACTERIAL CONCRETE or self healing concrete.

•It is specially made to increase the lifespan or the durability of concrete structure by the self healing action of that concrete.

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INTRODUCTION•Crack formation is a typical phenomenon related to durability.

•Percolation of cracks may lead to leakage problems, causing deterioration of the concrete matrix or corrosion of embedded steel reinforcement.

•In recent years a bacteria-based self-healing concrete is being developed in order to extend the service life.

•A two component healing agent is added to the concrete mixture.

•The agent consists of bacteria and an organic mineral precursor compound.

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WHAT SPECIAL PRESENT IN BIO CONCRETEThere are two thing present in bio concrete.1) The special bacteria that has to resist the alkalinity

and the mechanical stress of concrete.

2) The chemical precursor to activate the bacteria.

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Ca(C3H5O2)2 + 7O2 → CaCO3 + 5CO2 + 5H2O

CO2 + Ca(OH)2 → CaCO3 + H2O(carbonation)

• The activated precursor intern induces the bacteria to react with that precursor and form a base of calcium carbonate called as limestone, the chemical equation is given below.

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• When a concrete structure is damaged and water starts to seep through the cracks that appear in the concrete, the spores of the bacteria germinate on contact with the water and nutrients. Having been activated, the bacteria start to feed on the calcium lactate. As the bacteria feeds oxygen is consumed and the soluble calcium lactate is converted to insoluble limestone. The limestone solidifies on the cracked surface, thereby sealing it up.

• The consumption of oxygen during the bacterial conversion of calcium lactate to limestone has an additional advantage. Oxygen is an essential element in the process of corrosion of steel and when the bacterial activity has consumed it all itincreases the durability of steel reinforced concrete constructions.

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• The two self-healing agent parts (the bacterial spores and the calcium lactate-based nutrients) are introduced to the concrete within separate expanded clay pellets 2-4 mm wide, which ensure that the agents will not be activated during the cement-mixing process. Only when cracks open up the pellets and incoming water brings the calcium lactate into contact with the bacteria do these become activated.• Testing has shown that when water seeps into the concrete, the bacteria germinate and multiply quickly. They convert the nutrients into limestone within seven days in the laboratory. Outside, in lower temperatures, the process takes several weeks.

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BEFORE HEALING AFTER HRALING

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HOW THE HEALING AGENTS ARE APPLIED

1)BY DIRECT APPLICATION The bacteria and the chemical precursor(calcium

lactate) are added directly while making the concrete.

2) ENCAPSULATION LWA a) The part of the coarse aggregate is replaced by

the light weight aggregate(LWA) , which is impregnated with twice the calcium lactate solution and the spores of bacteria.

b) After impregnation the clay particles with 6% healing agents and the concrete is made .

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ADVANTAGES :

• Microbial concrete in crack remediation .

• Better attack towards freeze-thaw attack .

• Reduction in permeability .

• Reduction in corrosion of reinforced concrete .

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DISADVANTAGES : • Cost of bacterial concrete is double than conventional concrete .

• Growth of bacteria is not good in any media and atmosphere .

• There is no IS code or any other code for design of concrete with bacteria.

• Investigation of calcite precipitation is costly .

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EVALUATION • The Concrete properties should not be negatively

affected by addition of a healing agent to the concrete mixture.

• A large amount of bacteria and certain mineral precursor compounds like calcium lactate do substantially influence concrete compressive and tensile strength

• When the healing agent is added, Optimization of healing agent is necessary so that it wont affect the characteristics of concrete

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A series of experiments was conducted by growing marine bacterium from 25 to 55°C and alkali PH range of 7 to 12 to test the thermophilic and alkaliphilic potentialof the bacterium. Biofilm ability of the bacterium was screened using crystal violet assay by tube method11. Four specimens (50 mm) were prepared by mixing ordinaryPortland cement with tap water using a water/cement weight ratio of 0.48. Bioconcrete specimens were prepared by centrifugation of bacterial cells during stationary phase followed by washing the cells with distilled water to remove chloride ions and the pellet was diluted to 10^5 cells/ml concentration. Mix proportion of cement, sand and aggregate (Chips) in 1:1.5:3 (by weight) and cell suspension cement ratio was fixed to 0.48 for a concrete grade of M30. Two mixtures were prepared one with cell suspension and other with water as control. When the mixture was set, it is then taken off from the specimen and it is then put for curing and the compressive strength for each 3days, 7days, 14days and 28days is carried out.

Research Article

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The addition of marine bacterium at 105 cell/ml concentration gives the maximum improvement in compressive strength. It can be observed that theoptimum concentration of marine bacterium concrete is also 105 cell/ml. Here incorporation of a high number of bacteria appeared to have a good effect on compressive strength development as bacterial test specimen appeared almost 15% stronger then control specimen at all tested times. Effect of bacteria on development of strength appeared however strongly dependent oncompound identity. The biofilm producing bacteria has ability to form rich polysaccharide layer which absorbs the water and has the good potential to give the compressive strength to the concrete which was the mostpeculiar feature of this kind of bacteria. Additions of calcium lactate did not significantly affect strength development as control specimen.

RESULTS

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• The concrete which is made with concrete wastes which is eco-friendly so called as “Green concrete”.

• Concrete that uses less energy in its production & produces less carbon dioxide than normal concrete is Green Concrete .

• “Green concrete” is a revolutionary topic in the history of concrete industry . This was first invented in Denmark in the year 1998 by Dr.WG.

INTRODUCTION

GREEN CONCRETE

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PRODUCTION OF GREEN CONCRETE

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ADVANTAGESo Reduction of the concrete industry's CO2-emmision

by 30 %.o Increased concrete industry's use of waste

products by 20%.o Green concrete requires less maintenance and

repairs.o Green concrete having better workability than

conventional concrete.o Good thermal resistant and fire resistant.o Compressive strength behavior of ceracrete with

water cement ratio is similar to conventional concrete.

o Flexural strength of green concrete is almost equal to that of conventional concrete.

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LIMITATION

o By using stainless steel, cost of reinforcement increases.

o Structures constructed with green concrete have comparatively less life than structures with conventional concrete.

o Split tension of green concrete is less than that of conventional concrete.

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SCOPE IN INDIAo “Green concrete” is a revolutionary topic in the

history of concrete industry.o As green concrete is made with concrete wastes it

does take more time to come in India because industries having problem to dispose wastes.

o Also having reduced environmental impact with reduction in CO2 emission.

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LIGHT TRANSMITTING

CONCRETE

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•  Litracon is a light transmitting concrete . It is a strong and solid material, even though it allows light to transmit through it .

• Litracon is the newest most functional revolutionary element . It is a green constructional element , since it allows lots of sunlight through it during day time , and it is an energy saving, eco-friendly material too. In terms of aesthetics., it has wide versatility . It creates a magic on the walls with the aid of light and shadow. Hence it becomes a feast to our eyes.

• Litracon was invented by young Hungarian architect Aron Losonczy. • In 2001,he successfully produced the first Litracon block. After a few years ,in 2004 he started a German based company ‘’ LiTraCon ‘’

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• It is manufactured as a prefabricated block. The concrete is embedded with thousands of optical glass fibers. These fibers form a matrix and run parallel between the two main surfaces. The fibers make up only a small proportion of the total volume of the block; approximately 4%.

• These fibers mingle within the concrete, and because of their size, become a structural component, similar to a conventional aggregate. The surface of the material therefore retains the appearance of homogeneous concrete. In this manner, the result is not only two materials glass and concrete mixed but a third, new material, which is homogeneous in its inner structure and on its main surfaces as well. The result is a transformation. A solid gray mass becomes a luminous wall, alive with shadows .

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Principle of operation

Optical fibers work as a cylindrical waveguide that transmits light along its axis , by the process of internal reflection.

• Core - The thin glass center of the fiber where the light travels.

• Cladding - The outer optical material surrounding the core that reflects the light back into the core. To confine the reflection in the core, the refractive index of the core must be greater than that of the cladding.

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• Coating - Plastic coating that protects the fiber from damage and moisture . solution used the same principle. For translucent concrete panel, needed a core material such as acrylic that will transmit light continuously into the inside of the building, a white cladding layer that reflects the light back into the core and concrete as the protective coating . With this idea, researchers tried with acrylic cylinders of different diameters to evaluate its reflection when casted into different mixes using white cement and white aggregates and sand. With those result researchers found a diameter that could reflect enough light using our standard 10cm thick panel cast into our typical white concrete mix.

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APPLICATIONSWhile there are limited examples of translucent concrete currently in use, some of the potential applications under consideration for implementation include:• Translucent concrete inserts on front doors of homes, allowing the resident to see when there is a person standing outside.

• Subways using this material could be illuminated with daylight.

• Translucent concrete walls on restaurants, clubs, and other establishments to reveal how many patrons are inside.

•Ceilings of any large office building or commercial structureincorporating translucent concrete would reduce lighting costs during daylight hours.

• Lane markers in roadways could incorporate various colors in the translucent concrete, allowing for dynamic adjustments when required by traffic fluctuations.

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ADVANTAGES•Litracon is a green building material. Hence can be used Office buildings, or commercial structures, reduces the lightning cost during daylight hours.

•Illuminated Pavements: Speed bumps if illuminated are more visible. Also illuminated sign boards .

•Homogeneous: Similar structural properties as that of traditional concrete are shown.

•Plastering or finishing work on surface is not required. Just surface is to be polished with sand paper to obtain a smooth translucent surface.

•Routine maintenance not required.

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DISADVANTAGESCost : Litracon blocks cost about EUR 1300/m2 due to the usage of Optical fiber , which is a costlier material. Hence initial cost is high.

Labours : Labours with technical skills and experience is required for handling of LTC blocks.

Litracon is a factory product. Cast-in-situ is not possible.

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CONCLUSION• Light transmitting concrete or translucent concrete is an emerging trend in concrete technology . It is considered as a special concrete which ensures future benefits .

• It is a green building material reducing the lightning cost during day time. It is proved to provide both aesthetic appearance and structural stability.

• LTC blocks can be used to build up to 20m high load bearing walls.

• If the price of the product gets reduced, it is sure that the future construction industry will be in the hands of litracon .

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The concrete blocks are prepared in a pre-fabricated mould with fine grained concrete and translucent fabric. Transparent blocks are prepared by relatively small amounts of fiber, consistency and solidity of transparent concrete. The process of making cubes in this process is same as regular concrete cube. The only difference is presence of optical fiber. The perforated plates are kept in position that it should allow fiber from one end to another without any obstacles. The mould is lined with grease or benzene oil to give it a smooth surface texture; hundreds of strands of optical fibers are passed through the holes in perforated sheets.The concrete mix is poured in to the mould layer by layer without disturbing the fiber by avoiding voids and mould is well compacted carefully . The mould is kept for 24hours for making it hard and next day the cube is demoulded carefully and the extra fiber is removed with the help of blade and surface is polished. The cube is kept for curing and strength is calculated for 7th, 28th day respectively.Mix Design The main objective is to determine the proportion of ingredients that would produce a workable concrete mix which gives required strength. In this study, three mortar specimens were prepared with w/c ratio of 0.45. The percentage of plastic optical fiber used is 5% by volume.

Experimental program

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Wooden mould.perforated sheets.

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Perforated plates with optical fibers.

casted mould

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Volume of the each cube =512000 mm3Volume of the fiber in one bundle =1050.32 mm3Total vol of the fiber in 1 cube =25207.68 mm3Percentage of Fiber in each cube (volume %)= 4.928 ≈ 5% % of fiber in each cube is = 5%

Weight of mortarWeight of mortar =1.024kg/cubeDensity of mortar = 2000kg/m3w/c ratio = 0.45 (1:2)Weight of fine aggregate = 337g /cubeWeight of cement = 686g/cube

Compression strength test using POF7-day Compression strength ( LOAD /AREA ) = (190 / ( 80*80*100 ) )= 29.68 N/mm2

28-day compression strength = 37.03 N/mm2

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Results and DiscussionThe compressive strength for mortar cubes with and without POF has been calculated for 7 and 28 days. From the test results, it is observed that compressive strength for 7 day with POF is 29.68 N/mm2 and that for 28 day is 37.03 N/mm2. It is well known that compressive strength of any mortar specimen should greater then 23N/mm2 according to ASTM C109 Part: 2. The value of compressive strength for conventional concrete for 7 day is 35.52 N/mm2.

ConclusionIt can be concluded that, compressive strength value using optical fibers do not have much reduction when compared to conventional concrete. The compressive strength of concrete cube also depends on diameter of the holes in the perforated sheets. Green buildings would get an easy accreditation under daylight savings with this. Large and tall office buildings can share the lighting when the ceilings are translucent. Energy savings as well as heat insulation simple adds to the list of its amazing properties. Translucent concrete is the future, as it is the smart way of optimising and utilising light, a smart way of living.

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REFERENCES

Indian concrete journal volume 77 -January -2003-N0.-1 Green concrete technology by R.M. Swamy on page no. 878

www.litracon.com

www.wikipedia.com

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THANK YOU