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Published by Parthasarathi Sen, 2019-10-25 05:47:59

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WASTE & RECYCLED
MATERIAL IN CONCRETE

TECHNOLOGY

CONTENTS

Ø NEED OF RECYCLING OF WASTE MATERIALS
Ø ROLE OF WASTE MATERIALS IN CEMENT CLINKER

PRODUCTION
Ø PORTLAND CEMENT MANUFACTURE FROM WASTE

MATERIALS
Ø RECYCLING OF CONCRETE.
Ø MINING & QUARRYING WASTES
Ø APPLICATION OF MISCELLANEOUS WASTES
Ø ROLE OF WASTE MATERIAL AS AGGREGATES

ABSTRACT

• World wide consumption of concrete amounts to more than
1000 Kgs/person

• The demand is expected to increase in future
• Concrete comprises in quantity the largest of man made

material

INTRODUCTION

Concrete made with Portland cement ,water admixtures and
aggregates comprises in quantity the largest of all man made material

Historically whenever new compounds were produced ,or
waste materials accumulated in industries ,they were incorporated as
one of ingredients of concrete. Typical examples are fly ash
phosphogypsum,blast furnace slag, saw mil waste, rice husk, cotton
etc.The wide spread need for conserving resources & environment will be
reflected major emphasis on the use of wastes & by products.

Recycling of concrete materials also offers some promise.
Attempts are already being made to use municipal refuse & waste oil as

NEED OF RECYCLING OF WASTE
MATERIALS

Ø Rise in population
Ø Large scale demand for housing
Ø Over stressing the reserves of traditional building

materials
Ø Cement material presently not in a position to cope

the millions of the country
Ø The enormous amount of waste materials
Ø Recycling becoming imperative & mandatory

ROLE OF WASTE MATERIAL IN CEMENT
CLINKER PRODUCTION

Ø Many waste materials contain basic
ingredients that are needed for the
manufacturing of cement clinker

Ø Fly ash can also be used as a source of raw
material

COMPRESSIVE STRENGTH OF MORTAR (MPA)

Cement 1 day 3 days 7 days 28 days
17.3 26.2 37.4 53.7
Phosphogypsum
Minerals 8.2 22.0 37.4 50.0

Normal Cement

PORTLAND CEMENT MANUFACTURED FROM WASTE
MATERIALS

Ø FLY ASH CEMENT

Ø BLAST FURNACE SLAG CEMENT
Ø RICE HUSK ASH CEMENT

FLY ASH CEMENT

Ø Fly ash is the ash component of Coal liberated during
combustion .

Ø Fly ash can be incorporated into Portland cement in one of
the three ways.

Ø Fly ash can be used as a admixture or as replacement of
Portland cement.

Ø Fly ash addition to Portland cement results in increased
workability.

Ø In fly ash cement development of compressive strength is
slow

Ø At longer periods of curing Fly ash concrete develops higher

WHY CHARACTERISTICS?

Ø Not a specially manufactured product governed by
strict rules

Ø Variation in carbon, particle shape & size distribution,
presence of minerals etc..

Ø Exhibits different characteristics with different
compounds.

Ø No proper processing is available.
Ø Change in the behavior of concrete.

MACROSCOPIC VIEW OF FLY ASH

FLY ASH

Ø Finely divided residue resulting from combustion of
powdered coal.

Ø Common ingredient in concrete.
Ø First used in construction of Hungry Horse Dam in USA
Ø In India, first used in Rihad Dam.
Ø High volume fly ash is of current interest.
Ø Quality of fly ash is governed by IS:3812-1981

INFLUENCE OF FLY ASH ON STRENGTH
DEVELOPMENT IN CONCRETE

PERMEABILITY OF FLY ASH CONCRETE

Hungry Horse Dam, Montana, is a thick-arch structure
that was built between 1948 and 1953 with concrete

containing 120,000 metric tons of fly ash. The use of coal
fly ash in cement and concrete displaces Portland
cement.

Fly ash used in the construction of buildings at Chennai

Roman Coliseum: An classic example of Roman structures which was build with fly ash concrete.

COMPRESSIVE STRENGTH 90 DAYS

ASH 3 7 DAYS 28 DAYS 63.9
CEMENT DAYS 60.7

WELCOME70:30 31.9 45.4 58.7

50:50 26.1 39.0 57.6

30:70 24.0 35.4 42.7 50.1

0:100 22.4 32.5 42,4 47.4

ADVANTAGES OF FLY ASH CONCRETE

Ø Addition of fly ash to concrete minimize or eliminates the expansion due
to alkali aggregate reaction

Ø WORKABILITY
Ø TIME OF SETTING

DURABILITY OF FLY ASH CONCRETE

Ø Sufficiently cured fly ash concrete has dense structure & hence more
resistance to deleterious substances.

Ø This reduces the corrosion of reinforcement.

Ø Class F fly ash reduces alkali-silica reactivity because of the dense structure &
hence expansion is reduced which increases durability.

STRUCTURES USED FLY ASH ASH

Sl. No Structures State Cement replaced Source of fly
1. (%) ash
2. Gurgoan Haryana 15 Delhi
3. tunnel Delhi
4. Rajasthan 20
5. Jawar sagar 20 Neyveli
6. Dam Kerala 15 Harduaganj
7. U.P. 15
8. Kakki Dam 15 Bokaro
UP Bokhara
Navora Bihar Not available Durgapur
barrage 25 Talcher
Rihad Dam Assam
Bihar
Sone Barrage
Umium
Project

Chandil dam

FLY ASH MISSION PROJECT SITES

BLAST FURNACE SLAG CEMENT

Ø Portland blast furnace slag cement can replace Portland
cement where high strength is not required.

Ø It is produced by intergrinding Portland cement clinker &
granulated blast furnace slag.

Ø The workability of this cement is as good as Portland cement
concrete.

Ø This is resistant to a number of aggressive agents including
sulphates of Al,Mg,NH4 etc…

Ø The rate of hardening is slower than the normal Portland
cement concrete.

Ø The 90 days strength is ≤ of Portland cement concrete.

RICE HUSK ASH CEMENT

In the rice milling operation one ton of rice paddy
produces 400 kg of husk. Burning of the husk results in 20% by a
weight of ash. Blending this ash with cement produces a suitable
blended cement

ADVANTAGE

Ø The rice husk ash cement on hydration produces practically
no Ca(OH)2 &hence is superior to Portland.

RECYCLING OF CONCRETE

Ø Except structures which have to be preserved as moments a
great number of them have to be demolished sooner or later.

Ø Concrete accounts of nearly 75% by weight of all construction
material.

Ø Millions of tons of concrete debris are generated by natural
disaster.

WHAT IS CONCRETE RECYCLING…?

Breaking , removing & crushing hardened concrete from an
acceptable source. Old concrete pavements often are
excellent sources of material for producing RCA

RECYCLING PROCESS

USES OF RECYCLED CONCRETE

Ø Smaller pieces of concrete are used as gravel for new construction projects.
Ø Sub base gravels laid down as the lowest layer in a road.
Ø Recycled concrete can also be used as the dry aggregate for brand new

concrete.
Ø Larger pieces can be used for erosion control.

MINING & QUARRYING WASTES

Ø Large amount of wastes produced in mining & quarrying
operations.

Ø Mineral mining wastes are “waste rock” or “mill tailings”.

Ø Manufacturing of bricks ,light weight aggregates & autoclaved

CONCRETE RECYCLING MACHINE

APPLICATION OF MISCELLANEOUS WASTES

Ø Collier spoil
Ø Waste glass
Ø Red mud
Ø Burnt clay
Ø Saw dust

COLLIERY SOIL

Ø In coal operations about one half of the material is separated
& discarded as colliery soil.

Ø This soil is used to fill in road embankments.

Ø It can also be used to produce light weight concrete.

WASTE GLASS

Ø Millions of tons of waste glass are generated annually..
Ø The strength of concrete less than with gravel aggregate.
Ø This is used to make light weight aggregates.

RED MUD

Ø Red mud is a waste product resulting from the extraction of
alumina from bauxite ore.

Ø It is sufficiently plastic to be moulded into balls.

Ø Firing at about 1260 to 1310 c produces a strong dense
aggregate.

SAW DUST

SAW DUST

Ø Saw dust concrete is used only to a limited extent because of
its low strengths.

Ø The addition of sand can improve strength.
Ø Saw dust cement has a good insulation value .
Ø Low thermal conductivity.
Ø Concrete containing large amounts of saw dust is flammable.

ROLE OF WASTE MATERIALS AS AGGREGATES
Ø Use of waste & byproducts as aggregates has greater potential

because 75% of concrete is composed of aggregates.

Ø Various aggregates examined includes reclaimed concrete mining
& quarrying wastes, colliery soil, waste glass, red mud, burnt clay
& saw dust

CONCLUSION

In the coming future Recycling of Waste Materials
& by production for concrete technology will achieve new
heights, as attempts are already being made to use
municipal refuse & waste oil as partial substitutes for
production of cement clinker. We have to promote &
development in the area of utilization of waste materials.

Variability of the physical & chemical characteristics
& availability at locations far removed from populations
areas may inhibit the wide spread use of many types of
wastes. Future work will have to be directed to study of
the long term durability of concretes containing these
materials.


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