A Project Report on Flyash

A PROJECT REPORT ON FLYASH

In Partial Fulfillment for the Award of Bachelor of Technology Degree Of Rajasthan Technical University, KOTA

2014-2015

Submi tte tted d by :-

ABHIJEET PARASHAR RAVI PRAKASH SWAMI BHARAT BHUSHAN PIPLIWAL

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ACKNOWLEDGEMENT

We thank the Head of the Department of CIVIL ENGINEERING(CE), Prof. Dr .D.K SHARMA for cooperating us for making this project.Our special thanks go to the Principal, GRIET, Prof., for giving us such a wonderful opportunity to do this project.Without these people, it wouldn’t have been possible to do this project on “ROLE OF FLY-ASH BRICKS IN CONSTRUCTION”. CONSTRUCTION”.

ABHIJEET PARASHAR RAVI PRAKASH SWAMI BHARAT BHUSHAN















ABSTRACT

Fly ash is a fused residue of clay minerals present in coal. The high temperature generated when coal burns in thermal power plants, transforms the clay minerals in coal powder into a variety of fused fine particles of mainly aluminium silicate composition.

Pulverized fuel ash commonly known as fly ash. It is a useful by-product from thermal power stations using pulverized coal as fuel and has considerable pozzolonic activity. This national resource has been gainfully utilized for manufacture of fly ash-lime bricks as a supplement to common burnt clay buildings bricks leading to the conservation of natural resources and improvement in environment quality. Fly ash-lime bricks are obtained from materials consisting of pulverized fly ash in major quantity, lime and and an accelerator accelerator acting as a catalyst. Fly ash-lime bricks are generally manufactured by intergrading blending various raw materials are then moulded into bricks and subjected to curing cycles at different temperatures and pressures. On occasion as and when required, crushed bottom fuel ash or sand is also used in the composition of the raw material. Crushed bottom fuel ash or sand is also used in the composition as a coarser material to control water absorption in the final product. Fly ash reacts with lime in presence of moisture from a calcium hydrate which is a binder material. Thus fly ash – lime in presence of moisture form a calcium – silicate hydrate which is binder material. Thus fly ash – lime brick is a chemically ended bricks. These bricks are suitable for use in masonry construction construction just like common burnt clay bricks.















CONTENTS 1. INTRODUCTION INTRODUCTION 1.1 General 1.2 Utilization of fly ash in cement and bricks 1.3 Fly ash production 1.4 scope and objectives

2. LITERATURE REVIEW 2.1 General 2.2 Characteristics of fly ash 2.2.1 Physical Physical Properties Properties Of Fly Ash Ash 2.2.2 Chemical Compositions Compositions Of Fly Ash 2.2.3 Mineralogy of Fly Ash 2.2.4 Reactivity 2.3 Classification of Fly Ash 2.4 Fly Ash utilization 3. FLY ASH BUILDING BLOCKS/BRICKS 3.1 Raw Materials Required 3.1.1 Fly Ash (pulverized fuel ash) 3.1.2 Lime 3.1.3 Gypsum 3.1.4 Sand















3.3 Market Demand 4. METHODOLOGY 4.1 Manufacturing process of bricks 4.2 Characteristics of Fly Ash Bricks 4.3 Technical Specifications Specifications 4.4 Comparison of normal clay bricks and Fly F ly ash bricks 4.6 Fly Ash Brick Site Visit 4.7 Brick making making machines 4.8 Advantages & Disadvantages Disadvantages 4.9 Uses 5. TEST RESULTS AND DISCUSSION

5.1 General 5.2 Test results 5.2.1 WATER ABSORBTION TEST 5.2.2 COMPRESSIVE STRENGTH TEST

6. CONCLUSION CONCLUSION 7. BIBILOGRAPH















INTRODUCTION 1.1 GENERAL

Fly ash brick First invented in 2007..... American civil engineer Henry liu announced the invention of a new type of fly ash brick in 2007. Lius’s brick is compressed compressed of at 4,ooo psi and cured for 24 hrs in a 150 F(66 C) steam bath, then toughened with air entrainment agent , so that it lasts for more than 100freeze 100freeze thaw cycles. Owing to high concentration of calcium in class c fly ash , the brick can be described as self cementing. Since method contains no clay and uses pressure instead of heat ,it saves energy, reduces mercury pollution,costs 20% less than traditional manufacturing techniques. This type of brick is now manufactured under license in USA. Fly ash bricks are constructed at least partially from the residue of burnt coal .Depending on the type of coal that is burned, the resulting fly ash can take a number of different forms. Some kinds of fly ash require a cementing agent, such as quicklime or Portland cement . Other types contain a large enough percentage of lime that they are self setting, requiring only the addition of water to be turned into fly ash bricks. These bricks have been utilized in construction since the 1950s in some parts of the world, and in certain configurations are able to meet or exceed specifications for clay or cement bricks. When coal is burned, one of the results is a fine powder known as fly ash. While other ashes might settle at the base of the furnace where the coal is being burned, fly ash is light and fine enough that flue gases often are able to carry it up through the chimney. In the past, this ash was typically allowed to escape into the atmosphere, though in many locations environmental regulations the fly ash must be captured for safe disposal or reuse. Since toxic materials like mercury and lead may be highly concentrated in fly ash, this can lead to environmental or health concerns.

















1.2 UTILISATION OF FLY ASH IN CEMENT AND BRICKS

It has been above 70 years to research and use fly ash. With its application, the action mechanism of fly ash had been recognized. During the initial stage, only its pozzolanic activity is paid attention [ 8 and 9]. Many researchers devoted themselves to the research of the potential activity of fly ash and the hydration process of fly ash cement. With the deepening of the cognition for fly ash properties, some people found that the particles of fly ash have the morphology that is different to other pozzolanic materials. It is the unique particle morphology to make it have the ability reducing water, which other pozzolanic materials do not have [ 10, 11, 12 and 13 ]. and In 1981, Yinji [ 15 ] and Danshen [ 16 ] summarized the previous research results and put forward the hypothesis of "fly ash effects." They considered that fly ash has three effects in concrete, i.e., morphological, activated and micro aggregate effects. The three effects are relative each other. This shows that the morphological effect is the important aspect of fly ash effects.

1.3 Fly Ash Production

In each country utilization of fly ash depends on the local condition and has much to do with the fact that fly fl y ash is multifunctional material and can be used for various purposes. In the building industry fly ash can be used in different ways for different products. In concrete fly ash can be used as partially replacement of cement and/or sand to enhance workability of fresh concrete, to reduce heat of hydration and to improve concrete impermeability and resistance to sulfate attack.The properties of fly ash are varying depending on the coal kind and origin and on the power plant mode of operation. In certain uses some kind of beneficiation is required, either to improve its properties for the specific use or to achieve homogeneity. In concrete, fly

















Table 1 Fly ash production and utilization

S.NO

ZONE NAME

FA GENERATION

UTILIZATIONS

UTILIZATIONS

(Million tones)

(Million tones)

(%)

1.

SOUTHERN

13.5

0.8

6

2.

WESTERN

16.5

0.8

5

3.

EASTERN

10.21

2.94

28.8

4.

NORTHERN

15.5

2.3

14.8

6.84

54.6

TORAL

55.71

(ALL INDIA)

The minimum and maximum percentages of fly ash in PPC, specified by IS – 456, have risen from 10% to 15% and from 25% to 35% respectively. The government of India has issued a notification that makes it mandatory to use at least 25% ash in the manufacture of clay bricks, blocks, or tiles within a radius of 50 km from f rom coal or lignite based thermal power plants.

















1.4 SCOPE AND OBJECTIVE OF STUDY

The relationship of fly ash bricks to construction sector, in the context of fly ash generation by coal based thermal power plants.The present status of fly ash brick manufacture in India, availability of fly ash, and potential of utilization of fly ash bricks. Status of fly ash brick technologies in India by way of research work being done by various institutions, and technologies being used for manufacture of these bricks. Keeping in view, the technological status for fly ash brick manufacture, assessment of the technologies for its relevance and suitability, keeping in view material inputs required, energy requirements, costs, infrastructure requirements requirements etc. It may also be noted that various cements cements and mixes which can be made using fly ash, have the potential become raw materials for fly ash bricks and blocks of various specifications. Therefore, this aspect has also been discussed.Utilization of fly ash can result not only in reducing the magnitude of the environmental problems, but it is also to exploit fly ash as raw material for value added products (and conserve traditional materials), and for extraction of valuable valuable materials. Amongst many uses that that fly ash can be put to, to, that in building materials is particularly suitable. It is i s also anticipated, that there would be considerable short-fall in production of various building materials. According to a study, there would be a large short-fall in the production of bricks – to the tune of 25 billion bricks on an estimated demand of 100 billion bricks per year in India by the turn of the century.

















2. LITERATURE REVIEW

2.1

GENERAL

Fly ashes from Vijayawada thermal power plants were used in the experiments of the present study. A brief review of literature about the physical and chemical properties; mineralogy and morphology behavior of fly ashes is presented. Literatures regarding concrete applications of fly ashes have been used in construction are also discussed. Fly ash is produced from burning of pulverized coal in thermal power plants. The pulverized coal is fed into the boilers and burnt with the supply of additional air. The temperature in the boiler exceeds 1600 °C and the most of the mineral matter present in the coal are fused and altered physically and chemically. The resulting residue is called coal combustion by-products namely bottom ash, economizer ash, air pre-heater ash, and electrostatic precipitator ash (fly ash). These ashes are handled and disposed off separately owing to their differing qualities by mechanical, hydraulic and pneumatic conveying systems. The quality of ash produced is dependent on various factors like source coal and its degree of pulverization, design of furnace, changes in coal supply, changes in boiler load, and firing condition. Because of this inherent variability of the material, it is necessary to study the characteristics and engineering behavior of fly ash in detail before its use in an application.

















2.2.1 Physical Properties Of Fly Ash

The specific gravity, loss on ignition and specific surface area are are the prominent prominent physical properties of fly ashes. The specific gravity of fly ash may vary from 1.3 to 4.8 . The iron oxide content plays a decisive role in the specific gravity of the material. The specific gravity is more for fly ashes containing more iron oxide and vice versa. The presence of opaque spherical magnetite and hematite particles in sufficient quantity will increase the value of specific gravity to about 3.6 to 4.8. On the other hand, as the amount of quartz and mullite increases, the specific gravity decreases. decreases. However, coal particles particles with some minerallic minerallic impurities will have have lower specific gravity in the range 1.3 to 1.6. The range of specific gravity of Canadian fly ashes is reported to be in i n the range of 1.91 to 2.94 and that of American fly ashes in the range of 2.14 to 2.69.

2.2.2 Chemical Compositions Of Fly Ash

The main chemical compounds of class F fly ash are silica, alumina and iron oxide. Other minor constituents include oxides of calcium, magnesium, titanium, sulphur, sodium and potassium. Class C fly ash contains relatively higher proportion of calcium oxide and lesser proportion of silica, alumina and iron oxide than class F flyash. fly ash.

2.2.4 Mineralogy of Fly Ash

Fly ash consists of both crystalline and amorphous phases. The crystalline phases could be α− quartz, mullite, silimanite, crystallite, cristobalite, sulphates of iron, magnetite etc. The amorphous phases could be of silica and silicates predominantly of aluminium but containing calcium, magnesium, and iron in varying concentration with and without traces of sodium and



















flyashes the proportions were quartz (0 - 4%); mullite (0 –16%); magnetite (0 –30%); and hematite (1 –8%). The glass proportions in these fly ashes were found to range from 50 to 90%.. 90%. .

2.2.4.1 Reactivity

It is generally agreed that the glass or non-crystalline constituent of Class F fly ash goes into reaction with Ca(OH)2,which is added as lime or released from the hydration of portland cement. However, there are many other factors that influence there activity and relative rates of hydration such as fineness, particle shape, particle size distribution. Fly ash is generally judged for its quality in terms of strength behaviour. This is studied for pozzolanic characteristics in two approaches; lime reactivity strength(LRS) and pozzolanic activity index (PAI). IS:3812-1981,accords two grades to fly ash based on LRS2. Grade I is identified with a minimum 4 MPa LRS whereas fly ash with lower strength at 3 MPa is categorised as Grade II. The same code has also specified replacement compressive strength(PAI) at 80 percent as another yardstick. The LRS given forthese grades generally does not correlate with pozzolanic activity index. It is observed that certain fly ashes registering low LRS prove better for PAI and certain other fly ashes recording good LRS have shown lower PAI. Hence to as certain the suitability of fly ash as supplement to cement,the reactivity study in terms of PAI is desirable .



















Fly ash is comprised of the non-combustible mineral portion of of coal consumed in a coal fueled power plant. Fly ash particles are glassy, spherical shaped “ball bearings” — typically finer than cement particles — that are collected from the combustion air-stream exiting the power plant.

There are two basic types of fly ash:

A) Class F B) Class C. Both types react in concrete in similar ways. Both Class F and Class C fly ashes undergo a “pozzolanic reaction” with the lime (calcium hydroxide) created by the hydration (chemical reaction) of cement and water, to create the same binder (calcium silicate hydrate) as cement. In addition, some Class C fly ashes may possess enough lime to be self- cementing, in addition to the pozzolanic reaction with lime from cement hydration.

2.4 FLY ASH UTILIZATION



















3. FLY ASH BUILDING BLOCKS/BRICKS

3.1 General Fly Ash bricks are alternative to burnt clay bricks in the construction sector in India.At this time India is witnessing a new phase in development. With rapid economicgrowth and high rate of urbanisation. Construction provides the direct means for thedevelopment, expansion, improvement and maintenance of human settlements isparticular and economic growth in general. Construction activity accounts for morethan 50% of the development outlays in India. Building construction costs areincreasing at rates which are So per cent over inflation.

This is primarily due to the increase in the cost of basic building materials like burntbrick, steel, cement, timber, etc. As a result, the cost of construction usingconventional building materials and construction forms range from As. 40001- to As.6000/- per sqm even for normal housing. Construction costs of this order is beyondthe affordable capacity of the



















India, from Rajasthan fly ash will be available from Kota Thermal Power Plant that is 15 years old.It can also be obtained from the cities like Ahmadabad , Bikaner , Barmer etc.

3.2 Raw Materials Required

Fly Ash bricks are made of fly ash, lime, gypsum and sand stone and water . These can be extensively used in all building constructional activities similar to that of common burnt clay bricks. The fly ash bricks are comparatively lighter in weight and stronger than common claybricks. Since Since fly ash is being accumulated accumulated as waste material in large quantity near near thermalpower plants and creating serious environmental pollutionproblems, its utilisation as main raw material in the manufacture of bricks will not only create ample opportunities for its proper and useful disposal but also help in environmental pollution control to a greater extent in the surrounding areas of power plants







































3.2.2 Lime

Lime is truly a versatile material in building construction projects. Lime can be used to prepare the construction site by stabilizing the soil or remediating brownfield sites. Lime can be used in the construction of masonry systems as a component of mortar or the masonry unit. Exterior (stucco) and interior plaster systems can also contain lime. Finally, the decorative finishes can be created with lime washes. Lime provides benefits in the plastic and hardened state to mortars and plasters. In the plastic state, lime can enhance the workability and water retention of plasters and mortars. In the hardened state, lime products react with carbon dioxide to regenerate calcium carbonate or limestone. This is a slow, gradual process which increases the hardness of the finished surface and allows for the healing of hairline cracks by a process called autogenous healing. Since initial



















3.2.3 Gypsum

Gypsum is a very soft sulfate mineral composed of calcium sulfate dihydrate , with the chemical formula CaSO 4·2H 2O . It is found in alabaster , a decorative decorative stone used in Ancient Egypt . It is the second softest mineral on the Mohs scale of mineral hardness . It forms as an evaporite mineral and as a hydration product of anhydrite .

Gypsum is a common mineral, with thick and extensive evaporite beds in association with sedimentary rocks . Deposits are known to occur in strata from as far back as the Archaean eon



















Table 3.2.1: Grading limits of Fine Aggregates IS: 383-1970

IS SIEVE

Percentage passing by weight for

DESIGNATION Grading - I

Grading - II

Grading - III

Grading - IV

10 mm

100

100

100

100

4.75 mm

90-100

90-100

90-100

95-100

2.36 mm

60-95

75-100

85-100

95-100

1.18 mm

30-70

55-90

75-100

90-100





































The water is required for preparation of mortar, mixing of cement concrete and for curing work etc during construction work. The quality and quantity of water has much effect on the strength of mortar and cement in construction work.

Quality of Water : The water used for mixing and curing should be clean and free from injurious quantities of alkalis, acid, oils, salt, sugar, organic materials, vegetable growth and other substances that may be deleterious to bricks, stone, concrete or steel. Potable water is generally considered satisfactory for mixing. The pH value of water should be not less than 6.





















ii) Clay- Flyash Bricks :

Manufacturing process of clay flyash bricks by manual manual or extrusion process involves mixing mixing of flyash (60 %) with clay of moderate plasticity. The green bricks are dried under ambient atmospheric conditions or in shed to equilibrium moisture level of below 3 percent. Dried bricks



















3.5 Market Demand

180 billion tones of common burnt clay bricks are consumed annually approximately 340 billion



















Approximately 10,000 hectares of top soil is being lost every year for brick manufacturing and road construction. If we continue in this format, very soon, we will not have sufficient soil to produce our minimum required food.



















• Another type of fly ash brick is made by mixing soil, plaster of paris, fly ash and water, and allowing the mixture to dry. Because no heat is required, this technique reduces air pollution. More modern manufacturing processes use a greater proportion of fly ash, and a high pressure manufacturing technique, which produces high strength bricks with environmental benefits.



















• Economical & environment friendly. • 28% lighter than ordinary clay bricks. • Compressive strength: 7.5N/mm2 on an average.









































































































































































































A Project Report on Flyash

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