waste material concrete

8/10/2019 waste material concrete

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WASTE MATERIAL CONCR


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What is waste material concrete

Concrete is basically made of aggregates glued by a cementitipaste, which is made of cementitious materials and water.


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Why waste materials are used inconcrete?

Growth of cement usages leads to the greater production of CO2 gas which is one of the

GLOBAL WARMING


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Why waste materials are used inconcrete?

Excavation of sand and stone from rive banks is one of the main causes for disaster caus

FLOODS


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What are properties that wastematerial must have?

Similar grain size

Similar mechanical properties

Good workability

No effect on cement chemistry

Cost effective


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What are all the waste materials usin concrete?

Fly Ash

Rice Husk Ash

Blast Furnace Slag

Silica Slag

Copper Slag

Plastic And E-waste

C And D Waste


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Fly ash

It is residue left from burning coal, which is collected on an electrostatic p

in a baghouse. It mixes with flue gases that result when powdered coal is

electric power.

Fly ash is pozzolanic, which means its a siliceous or siliceous-and-alumi

that reacts with calcium hydroxide to form a cement.

When portland cement reacts with water, it produces a hydrated calcium

and lime

Properly selected fly ash reacts with the lime to form CSHthe same cemas in portland cement. This reaction of fly ash with lime in concrete impr

Typically, fly ash is added to structural concrete at 15-35 percent by weig

cement, but up to 70 percent is added for mass concrete used in dams, rol

concrete pavements, and parking areas.

Special care must be taken in selecting fly ash to ensure improved proper


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Fly ash


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Advantages :

The advantages of using fly ash far outweigh the disadvanta

The most important benefit is reduced permeability to water aggressive chemicals.

Properly cured concrete made with fly ash creates a denserbecause the size of the pores are reduced.

This increases strength and reduces permeability.


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Advantages :

The use of fly ash can result in better workability, pumpability, cohefinish, ultimate strength, and durability.

The fine particles in fly ash help to reduce bleeding and segregatioimprove pumpability and finishing, especially in lean mixes.

Properly proportioned concrete containing fly ash should create a

Good quality fly ash generally improves workability or at least produsame workability with less water. The reduction in water leads to imstrength.


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Disadvantages

Poor-quality fly ash can have a negative effect on concrete.

The principle advantage of fly ash is reduced permeability atbut fly ash of poor quality can actually increase permeability

Some concrete will set slowly when fly ash is used

Freeze-thaw durability may not be acceptable with the use oconcrete


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Rice husk ash

RHA, produced after burning of Rice husks (RH) has high reactivity andpozzolanic property.

Indian Standard code of practice for plain and reinforced concrete, 2000, recommends use of RHA in concrete but does not specify quan

Chemical compositions of RHA are affected due to burning process atemperature. Silica content in the ash increases with higher the burnintemperature.

RHA produced by burning rice husk between 600 and 700C temperahours, contains 90-95% SiO2, 1-3% K2O and < 5% unburnt carbon. Unde

burning condition in industrial furnace.

Portland cement contains 60 to 65% CaO and, upon hydration, a conportion of lime is released as free Ca(OH)2, which is primarily responsibpoor performance of Portland cement concretes in acidic environme

RHA replacing 10% Portland cement resists chloride penetration, improcapillary suction and accelerated chloride diffusivity.


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Application of Rice husk ash

From RHA we manufacture organic micro-silica / amorphous silica, withof above 89%, in very small particle size of less than 35 micronsSilpozz

in High Performance Concrete.

This product can be used in a variety of applications like:

green concrete high performance concrete refractory ceramic glaze insulator roofing shingles waterproofing chemicals oil spill absorbent specialty paints flame retardants carrier for pesticides insecticides and bio fertilizers etc etc.


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Advantages

RHA contains silica in amorphous and highly cellular form, with 50-1surface area.

RHA with cement improves workability and stability, reduces heat ethermal cracking and plastic shrinkage.

This increases strength development, impermeability and durabilitystrengthening transition zone, modifying the pore-structure, blockinvoids in the hydrated cement paste through pozzolanic reaction.

RHA minimizes alkali-aggregate reaction, reduces expansion, refinestructure and hinders diffusion of alkali ions to the surface of aggreporous structure.

Pozzolanic reaction of RHA consumes Ca(OH)2present in a hydratecement paste, reduces susceptible to acid attack and improves rechloride penetration.

This reduces large pores and porosity resulting very low permeabili


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Silica fume

Silica fume is a byproduct of producing silicon metal or ferrosilicon

its chemical and physical properties, it is a very reactive pozzolan.

Concrete containing silica fume can have very high strength and durable.

Silica fume is available from suppliers of concrete admixtures and,specified, is simply added during concrete production.

Placing, finishing, and curing silica-fume concrete require special a

the part of the concrete contractor.


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Silica fume

Silica fume consists primarily of amorphous (non-crystalline) silicon

The individual particles are extremely small, approximately 1/100thaverage cement particle

The quality of silica fume is specified by ASTM C 1240 and AASHTO


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Silica fume

The other names for silica fume:

Condensed silica fume

Microsilica

Volatilized silica

There are several materials that are physically and chemically quite simfume.

Precipitated silica

Fumed silica

Gel silica

Colloidal silica

Silica flour and silica dust


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process


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How does silica fume work in concre

In cementitious compounds, silica fume works on two levels, described here is a chemical reaction called the "pozzolanic" react

The hydration (mixing with water) of Portland cement prodcompounds, including calcium silicate hydrates (CSH) and calciu(CH).

The CSH gel is known to be the source of strength in concrete. Wheis added to fresh concrete it chemically reacts with the CH additional CSH.

The benefit of this reaction is twofold; increased compressive chemical resistance. The bond between the concrete paste andaggregate, in the crucial interfacial zone, is greatly increasedcompressive strengths that can exceed 15,000 psi.

The additional CSH produced by silica fume is more resistant toaggressive chemicals then the weaker CH.


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Advantages

Increased cohesion

Reduces bleeding

Enhanced mechanical property

Reduce permeability

Chlorine resistance

Avoid sulphate attack

Workablity

Resistance to acid or chemical attack


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Blast furnace slag

Ground granulated blast-furnace slag (GGBFS), referred to as slagglassy granular material formed when molten blast-furnace slag is chilled, as by immersion in water.

Ground granulated blast furnace slag (GGBFS) has been used for years as a supplementary cementitious material in Portland cemenconcrete, either as a mineral admixture or as a component of blencement.

The use of GGBFS as a partial Portland cement replacement takes

advantage of the energy invested in the slag making process andcorresponding benefits with respect to the enhanced cementitiouproperties of the slag.

Grinding slag for cement replacement requires only about 25 percthe energy needed to manufacture Portland cement.


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ENGINEERING PROPERTIES

Hydraulic Reactivity

Fineness

Strength Development

Workability

Low Heat of Hydration

Reduce Alkali-Aggregate Reactivity

Sulfate Resistance


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Advantages

There are two primary advantages for adding GGBFS to concretseparate material, rather than inter grinding it in the cement:

1. Each material can be ground to its own optimum fineness

2. The proportions can be adjusted to suit the particular proje


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Cont

The siliceous and silica-aluminous substances available in copconsidered pozzolanic; they react chemically with calcium hpresence of water at normal temperature to form cementitiothe form of a gel.

The siliceous and silica-aluminous substances available in copconsidered pozzolanic; they react chemically with calcium hpresence of water at normal temperature to form cementitiothe form of a gel.


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Uses of copper slag

Copper slag has also gained popularity in the building industfill material.

Contractors may also use copper slag in place of sand duringconstruction.

Copper slag can also be used as a building material, formed

Copper slag is widely used in the sand blasting industry and it

used in the manufacture of abrasive tools. Copper slag is widely used as an abrasive media to remove r

coating and other impurities in dry abrasive blasting due to ithardness (6-7 Mohs), high density (2.8-3.8 g/cm3) and low frecontent.


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Physical properties


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Plastic and E- waste

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waste material concrete