introduction · 2018. 7. 15. · reinforcement cement concrete works. the aggregate crushing...

EXPERIMENTAL STUDY ON STRENGTH AND DURABILITY

OF COAL ASH ADMIXED CONCRETE

Sudip Das

Assistant Professor, Aarupadai Veedu Institute Of Technology,

Vinayaka Missions University, Chennai –603104,

E mail: [email protected]

Abstract— This experimental study deals with Mechanical properties, compressive strength and

durability properties, alkalinity test, carbonation depth of coal ash admixed concrete with ordinary

concrete. The percentile of coal ash was varies from 5%, 10%, 15%, 20% and 25% in replacement of

cement. The influence of coal ash content in the concrete had been studied by measuring the compressive

strength of the concrete cubes for 7 days and 28 days. The influence of coal ash in concrete cubes has

been studied by measuring the maximum compressive strength and durability and by observing the

ultimate load capacity. The cubes were tested in Compressive Testing Machine.

Keywords: Coal ash, Compressive strength, Alkalinity test, Carbonation depth

1. INTRODUCTION

Concrete is a composite material which is being

used in variety of structures. More commonly

the construction material like aggregates,

cement, and steel bars are to be transported from

distant places to the site which is quite

expensive. Therefore, the aggregates are

preferably to be used available in the vicinity.

Due to development in infrastructure all around

the world, utilization of concrete is increasing at

a higher rate. Natural aggregates such as gravel

or crushed rock and sand are the major

constituent of the concrete. Few decades ago,

these aggregates have been easily available at

economic prices But, the negative impact of

increasing demand for concrete is leading to

extensive extraction of aggregates from natural

resources.

This excessive extraction results into

environmental degradation, ecological

imbalance and create a question about the

preservation of natural resources of aggregates.

So, it has challenge to every engineer and

researcher to develop new materials which can

replace the aggregates, and mitigate the

problems, related to preservation of natural

resources of aggregates. Apart from it, the

amount and type of industrial waste have

increased due to normal growth in population.

Many of industrial waste such as Coal bottom

ash, Blast furnace slag, Copper slag etc. cause a

waste disposal crisis, thereby leading to the

environmental problems. However, this

International Journal of Pure and Applied MathematicsVolume 119 No. 16 2018, 2117-2126ISSN: 1314-3395 (on-line version)url: http://www.acadpubl.eu/hub/Special Issue http://www.acadpubl.eu/hub/

2117

environmental problem can be reduced by

making more appropriate use of the industrial

waste. The use of industrial waste in concrete is

a suitable path towards effective disposal of

waste as well as preservation of natural

resources of aggregates.

Several researchers have investigated the

optimum use of CBA as Cement in concrete and

its effects on the different mechanical and

durability properties. The properties of CBA are

much similar to Cement. Therefore it could be

regarded as the substitute of the Cement in

concrete construction. The use of this ash in

concrete provides potential environmental as

well as economic benefits for concrete industries

and particularly in thermal power plant where a

considerable amount of CBA is produced.

2. SCOPE OF THE PROJECT:

To identify alternative source of good

quality material as cement content and

also try to minimize the negative impact

on environment.

To ensure the sustainability

development and eco friendly

construction technique by using

industrial waste.

To reduce the cost of construction by

using waste materials.

3. LITERATURE SURVEY

Influence of High Temperature On Compressive

Strength Of Coal Bottom Ash Concrete

Devinder Singh1 and Jaspal Singh

2 It is very

important to observe the thermal stability of

concrete when exposure to higher temperatures.

So, this study aims to find the effect of elevated

temperature on the residual compressive strength

of concrete containing Coal Bottom Ash (CBA).

Five concrete mixtures were prepared at

different replacement levels of CBA (0%, 10%,

20%, 30%, and40%) with fine aggregates and

subjected to different temperature levels. Sixty

cubes were casted (with three cubes for each

testing condition) and cured for 28 days. Then

after, they were heated to 1500C, 3000C and

6000C for two and half hour duration in the

muffle furnace. The significant strength loss was

observed for all type of concrete after exposure

to1500C.There was more critical strength loss

for reference as well as CBA concrete, when

heated in range of 300-6000C. Based on the test

results, it can be concluded that the replacement

of fine aggregates with CBA cannot change the

strength properties of concrete during heating.

Durability Study On Alumina-Silicate Concrete

Synthesized Using Anthracite Coal Fly Ash.

S. Nagan11, K. Kannapiran

2 and T. Sujatha

2

described that ever since our ancestors

constructed dwellings, mortars such as mud, red

earth, lime, cement etc. played vital role as

binders. Of late it is found that production of

cement contributes significantly to emission of

CO2 and the quantum is manifold and

uncontrollable. This forces scientists to invent an

alternative binding material to cement.

International Journal of Pure and Applied Mathematics Special Issue

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Geopolymer, a member of inorganic family,

found as suitable substitute to cement need to be

tested for its durability and serviceability for

promotion globally. Fly ash, a by-product

produced by industry can be used as feedstock

for geo-polymer. Variations in the ratio of

aluminum to silicon in our Indian fly ashes, and

alkali to silicon, produce geo-polymers with

different physical and mechanical properties

demand intensive study. This paper describes the

durability property of dry- cured ―low-calcium

fly-ash-based geo-polymer concrete‖. The

experimental work involves conduct of

durability tests currently available for OPC as

per ASTM standards on low-calcium Indian fly

ash based geo-polymer concrete. It has excellent

compressive strength, suffers very little drying

shrinkage and low creep, excellent resistance to

sulphate attack, and good acid resistance. The

Geopolymer concrete was dry cured at 70O C.

This paper effectively implies the variations of

M30 and M50grade of concrete with NaOH

molarities as 14M.

4. MATERIALS

CEMENT

Ordinary Portland cement is the

most common type of cement in general usage.

It is a basic ingredient of concrete, mortar, and

plaster. It consists of a mixture of oxides of

calcium, silicon and aluminum. Portland cement

and similar materials are made by heating

limestone (a source of calcium) with clay, and

grinding this product (called clinker) with a

source of sulfate (most commonly gypsum).

Generally, the OPC is classified

into three grades namely 33grade, 43 grade and

53 grade, of these Ordinary Portland Cement

with grade 43 has been used in this project. The

specific gravity of cement was 3.15 and fineness

of cement was 10%.

Specific gravity (Le – Chatelier flask)

(IS: 1727-1967)

Standard consistency (IS: 4031 – 1988

Part 4)

Initial setting time (IS: 4031 – 1988 Part

5)

Final setting time (IS: 4031 – 1988 Part

5)

3.2.2 AGGREGATES

Fine and Coarse aggregates

make up the bulk of a concrete mixture.

Aggregates are inert granular materials such as

sand, gravel, or crushed stone that, along with

water and Portland cement, are an essential

ingredient in concrete. For a good concrete mix,

aggregates need to be clean, hard, strong

particles free of absorbed chemicals or coatings

of clay and other fine materials that could cause

the deterioration of concrete. Aggregates, which

account for 60 to 75 percent of the total volume

of concrete, are divided into two distinct

categories-fines and coarse.

Recycled aggregates from

construction, demolition and excavation waste

are increasingly used as partial replacements of


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natural aggregates, while a number of

manufactured aggregates including air-cooled

blast furnace slag and bottom ash are also

permitted.

Decorative stones such as

quartzite, small river stones or crushed glass are

sometimes added to the surface of concrete for a

decorative ―exposed aggregate‖ finish, popular

among landscape designers.

3.2.3 FINE AGGREGATE

It may be either natural sand

e.g. river sand and Sea sand or Artificial sand

(Prepared by crushing stone and gravel to

powder form). Sand used as a fine aggregate in

concrete mix aggregate size is less than 4.75mm

and specific gravity is 2.60.

Functions of fine aggregate is to

produce workability and uniformity to concrete,

to fill up the voids to coarse aggregate, to assist

the cement paste to hold the particles of coarse

aggregate in the suspension and to prevent the

possibility of segregation.

3.2.4 COARSE AGGREGATE

The size of aggregate which is bigger

than 4.75mm is considered as coarse aggregate.

We have used 20mm size of coarse aggregate

that could be conveniently used for concrete

making. The specific gravity of coarse aggregate

was 2.65. Using the maximum size will result in

reduction of cement content, water requirement

and drying shrinkage.

It is mainly used for providing bulk to

the concrete. The strength of concrete depends

on the strength of the coarse aggregate and

hence selection of suitable coarse aggregate is

very essential. It should be hard, strong, dense,

durable, rough and free from salt, alkali and

organic matters. Blue granite, genesis,

crystalline and lime stone or good sand stone are

crusted into small pieces of varying sizes (5mm

to 20mm) and used as coarse aggregate in

reinforcement cement concrete works.

The aggregate crushing strength should

not exceed 45% and abrasion value should not

exceed 50% for aggregate in R.C.C. for light

weight concrete clinker slag, coke, coal etc., are

used as coarse aggregate. Well graded aggregate

provides denser concrete with lesser voids

3.2.5 WATER

Combining water with a cementitious

material forms a cement paste by the process of

hydration. The cement paste glues the aggregate

together, fills voids within it, and allows it to

flow more easily.

Less water in the cement paste will yield

a stronger, more durable concrete, more water

will give an easier flowing concrete with a

higher slump. Impure water used to make

concrete can cause problems, when setting, or in

causing premature failure of the structure. pH

value of water is 7 which is taken from IS code

456-2000 in clause IS 5.4.2.


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3.2.6 CONPLAST SP430:

CONPLAST SP430 is used where a high degree

of workability and its retention are required.

Where delays in transportation or placing are

likely or when high ambient temperature causes

rapid slump loss. It facilitate production of high

quality concrete

CONPLAST SP430 complies with IS:9103

:1999 and BS : 5075 part 3 and ASTM - C - 494

type ‗F‖ as a high range water reducing

admixture and Type G high dosage.

It is supplied as a brown

liquid instantly dispersible in water, it has been

specially formulated to give high water

reduction up to 25% without loss of workability

or to produce high quality concrete of reduced

permeability. Specific gravity up to 1.20 to 1.30

at 300C.

Table 1.1 Mix Proportions:

Table 1.2 Preparation of cube specimen for

compression strength

Type of

specimen

% of

coal ash

added

7 days 28 days

Conventional 0 3 3

Coal ash 5% 3 3

Coal ash 10% 3 3

Coal ash 15% 3 3

Coal ash 20% 3 3

Coal ash 25% 3 3

3.3 PROCESS OF MANUFACTURE OF

CONCRETE

Production of quality

concrete requires meticulous care exercised at

good stage of manufacture of concrete. It is

interesting to note that the ingredients of good

concrete and bad concrete are the same. With the

same material of intense care is taken to exercise

control at every stage it will result in good

concrete.

The various stages of manufacture of concrete

are

Batching

Mixing

Placing

Casting

Compaction

Curing

Cement Fine

aggregate

Coarse

aggregate

Water

362.63

621.06

1345.49

186

1

1.71

3.71

0.41


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3.3.1 BATCHING

Weight batching is the correct method

of measuring the materials. Use of weight

system in batching, facilities accuracy,

flexibility and simplicity. In our concreting job,

cement is accurately weighed and exact

proportion as designed is maintained.

3.3.2 MIXING

Mixing of reinforced concrete

needs careful conditions to avoid segregation

and the difficulty of mixing the materials

uniformly and increase in the aspect ratio,

volume percentage, size and quantity of coarse

aggregate intensify the difficulties and balling

tendencies.

Mixing of concrete may be done by any

one of the conventional method of hand mixing

(or) machine mixing. But it is necessary to have

a uniform dispersion and aggregate constituents

to prevent segregation or balling of aggregate

during mixing.

Mixing of RC required normal vibration

to move the mix and consolidate it into forms.

External vibration may preferable to prevent

segregation, the mixing was done by hand as the

specimen mould was small and quantity of mix

was less. Correct quantity of cement, sand,

aggregate and water required for batched were

weighted accurately. Cement and sand were

mixed with coarse aggregate.

Then the correct quantity is taken in a

wire mesh basket. And it was uniformly

dispersed throughout the mix. Then the ix was

thoroughly mixed by wearing glows to the hand.

In dry state water was added finally and mixing

was done gradually.

Hand mixing is adopted in this study as

the quantity of concrete required per batch was

very small. Cement, required amount of fine

aggregate were mixed thoroughly and kept

ready. Then required quantity of coarse

aggregate is added the mix and mixing is done

again. The required quantity of water is then

added with the mix. In the prepared mix the

required percentage of coal ash is added and

mixed thoroughly


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.

3.3.3 PLACING

It is enough that a concrete mix

correctly designed, batched, mixed and

transported, it is utmost importance that the

concrete must be placed in systematic manner to

yield optimum results.

3.3.4 COMPACTION

The test specimens are made as soon as

practicable after mixing and in such a way to

produce full compaction of the concrete with

neither segregation nor excessive laitance

3.3.5 CASTING

The specimens were cast in cast-iron

steel moulds. The inside of the moulds is applied

with oil to facilitate the easy removal of

specimens. Concrete mix is placed in three

layers and each layer is compacted with table

vibrator. The test cube specimens are made after

mixing and in such away as to produce full

compaction of the concrete with neither

segregation nor excessive laitance. The concrete

is filled into the cube mould in layers

approximately 5 cm deep.

Concrete slides form it, in order to ensure by

hand or by vibration. After the top layer has

been compacted the surface is brought to the

finished level with the top of the cube mould

using a trowel.

The standard tamping bar is used and the strokes

of the bar distributed in a uniform manner over

the cross section of the cube mould. The number

of strokes per layer required to produce the

specified conditions vary according to the type

of concrete. For specimens, in no case the

concrete should be subjected to less than 35

strokes per layer for 15cm cube. The stroke

penetrate into the under lying layer and the

bottom layer is needed throughout its depth.

Where voids are left by the tamping bar the sides

of the mould are tapped to close the voids.


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3.3.6 CURING

This is the method of curing because it

satisfies all the requirements of curing namely,

promotion of hydration, elimination of shrinkage

and absorption of heat of hydration. The casted

specimens are immersed in curing tanks for a

period of 7 and 28 days

The concrete still retains its alkaline

characteristic the color of the concrete

will change to purple.

There is no carbonation takes place in

the copper slag concrete at the age of 7

and 28 days.


2124

Table 1.3 Compressive Strength Results for

28 days cube specimen For coal ash Concrete

CONCLUSIONS

The compressive strength of the

specimen was compared with one

another and final outputs shows that

there is slight increase in

compressive strength when coal ash

is added with the concrete.

Hence Coal ash can be used as a very

good replacement material in the

preparation of plain concrete.

The coal ash admixed concrete with

cement content of 15 %is been

identified as the higher level of

strength.

The higher strength of coal ash

admixed concrete was recorded

29.22 N/mm2 at 7 days and

41.11N/mm2 at 28 days.

These results were concluded from

the study.

REFERENCES

IS:383-1970 Specifications for coarse

and fine Aggregates from Natural

sources for concrete. New Delhi, India:

Bureau of Indian Standards.

IS:10262-2009 Recommended

guidelines for concrete mix design. New

Delhi, India: Bureau of Indian Standards.

IS:1199-1959 Indian standard methods

of sampling and analysis of concrete.

New Delhi, India: BIS

IS:516-1959. Indian standard code of

practice- methods of test for strength of

concrete. New Delhi, India: BIS743

20.5525.1

28.6729.2221.72

19.33

010203040

0 5 10 15 20 25

com

pre

ssiv

e s

trn

gth

in

N/m

m2

Replacement in %

Compressive strength for 7

days

Compressive strength

NOS Moulds % of

coal

ash

added

Load

(KN)

Compressive

strength

( N/mm2)

1 Cube 0 785 34.89

3 Cube 5% 790 35.10

5 Cube 10% 872.5 38.78

7 Cube 15% 925 41.11

9 Cube 20% 515 32.88

11 Cube 25% 510 25.66


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introduction · 2018. 7. 15. · reinforcement cement concrete works. the aggregate crushing...

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