WASTE & RECYCLED MATERIAL IN CONCRETE TECHNOLOGY Presented By SABINA NARAYANAN.P
CONTENTS NEED OF RECYCLING OF WASTE MATERIALS ROLE OF WASTE MATERIALS IN CEMENT CLINKER PRODUCTION PORTLAND CEMENT MANUFACTURE FROM WASTE MATERIALS RECYCLING OF CONCRETE. MINING & QUARRYING WASTES APPLICATION OF MISCELLANEOUS WASTES 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 partial substitutes for the fuel in the production of cement clinker
NEED OF RECYCLING OF WASTE MATERIALS RRise in population Large scale demand for housing OOver stressing the reserves of traditional building materials CCement material presently not in a position to cope the millions of the country The enormous amount of waste materials RRecycling becoming imperative & mandatory
ROLE OF WASTE MATERIAL IN CEMENT CLINKER PRODUCTION MMany waste materials contain basic ingredients that are needed for the manufacturing of cement clinker FFly ash can also be used as a source of raw material Lime sludge can be used as a substitutes for lime stone RRed mud a waste material from the production of alumina used as a raw material for cement clinker production PPhosphogypsum as a mineralizer for making clinker
FLY ASH CEMENT Fly ash is the ash component of Coal liberated during combustion. Fly ash can be incorporated into Portland cement in one of the three ways. Fly ash can be used as a admixture or as replacement of Portland cement. Fly ash addition to Portland cement results in increased workability. In fly ash cement development of compressive strength is slow At longer periods of curing Fly ash concrete develops higher strengths than the normal concrete
WHY CHARACTERISTICS? Not a specially manufactured product governed by strict rules Variation in carbon, particle shape & size distribution, presence of minerals etc.. Exhibits different characteristics with different compounds. No proper processing is available. Change in the behavior of concrete.
FLY ASH Finely divided residue resulting from combustion of powdered coal. Common ingredient in concrete. First used in construction of Hungry Horse Dam in USA In India, first used in Rihad Dam. High volume fly ash is of current interest. Quality of fly ash is governed by IS:3812-1981
INFLUENCE OF FLY ASH ON STRENGTH DEVELOPMENT IN 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.
WELCOME ASH CEMENT 3 DAYS 7 DAYS28 DAYS90 DAYS 70:3031.945.458.763.9 50:5026.139.057.660.7 30:7024.035.442.750.1 0:10022.432.542,447.4 COMPRESSIVE STRENGTH
ADVANTAGES OF FLY ASH CONCRETE Addition of fly ash to concrete minimize or eliminates the expansion due to alkali aggregate reaction WORKABILITY TIME OF SETTING
DURABILITY OF FLY ASH CONCRETE Sufficiently cured fly ash concrete has dense structure & hence more resistance to deleterious substances. This reduces the corrosion of reinforcement. Class F fly ash reduces alkali-silica reactivity because of the dense structure & hence expansion is reduced which increases durability. Because of the reduced permeability the chloride ingress is reduced.
STRUCTURES USED FLY ASH ASH Sl. No StructuresStateCement replaced (%) Source of fly ash 1.Gurgoan tunnel Haryana 15Delhi 2.Jawar sagar Dam Rajasth an 20 Delhi 3.Kakki Dam Kerala 20 Neyveli 4.Navora barrage U.P. 15 Harduaganj 5.Rihad Dam UP 15Bokaro 6. Sone Barrage Bihar15Bokhara 7.Umium Project AssamNot available Durgapur 8. Chandil damBihar 25Talcher
BLAST FURNACE SLAG CEMENT Portland blast furnace slag cement can replace Portland cement where high strength is not required. It is produced by intergrinding Portland cement clinker & granulated blast furnace slag. The workability of this cement is as good as Portland cement concrete. This is resistant to a number of aggressive agents including sulphates of Al,Mg,NH 4 etc… The rate of hardening is slower than the normal Portland cement concrete. The 90 days strength is ≤ of Portland cement concrete. More resistant to sea water &other chemical agents than Portland cement.
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 The rice husk ash cement on hydration produces practically no Ca(OH) 2 &hence is superior to Portland.
RECYCLING OF CONCRETE Except structures which have to be preserved as moments a great number of them have to be demolished sooner or later. Concrete accounts of nearly 75% by weight of all construction material. Millions of tons of concrete debris are generated by natural disaster. Depletion of normal aggregate sources, stricter environmental laws & waste disposal problems make recycling of concrete.
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
USES OF RECYCLED CONCRETE Smaller pieces of concrete are used as gravel for new construction projects. Sub base gravels laid down as the lowest layer in a road. Recycled concrete can also be used as the dry aggregate for brand new concrete. Larger pieces can be used for erosion control.
MINING & QUARRYING WASTES Large amount of wastes produced in mining & quarrying operations. Mineral mining wastes are “waste rock” or “mill tailings”. Manufacturing of bricks,light weight aggregates & autoclaved concrete blocks.
APPLICATION OF MISCELLANEOUS WASTES Collier spoil Waste glass Red mud Burnt clay Saw dust
COLLIERY SOIL IIn coal operations about one half of the material is separated & discarded as colliery soil. TThis soil is used to fill in road embankments. IIt can also be used to produce light weight concrete.
WASTE GLASS Millions of tons of waste glass are generated annually.. The strength of concrete less than with gravel aggregate. This is used to make light weight aggregates.
RED MUD Red mud is a waste product resulting from the extraction of alumina from bauxite ore. It is sufficiently plastic to be moulded into balls. Firing at about 1260 to 1310 c produces a strong dense aggregate.
BURNT CLAY High permeability. Concrete contains burnt clay has high fire resisting capacity.
SAW DUST SSaw dust concrete is used only to a limited extent because of its low strengths. TThe addition of sand can improve strength. SSaw dust cement has a good insulation value. LLow thermal conductivity. CConcrete containing large amounts of saw dust is flammable.
ROLE OF WASTE MATERIALS AS AGGREGATES Use of waste & byproducts as aggregates has greater potential because 75% of concrete is composed of aggregates. 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.