Recycle & Reuse Of Waste Material In Civil

COLLEGE OF ENGINEERING PUNE

Abstract:The purpose of this paper is to

which makes it suitable for various architectural and decorative applications.

transmit information on the state of practice

Also, the reduction of portland cement

for recycling and reuse of concrete materials

production will reduce carbon dioxide

from building demolitions.

(CO2) emissions, reduce energy

Civilization also produces waste products. Disposal issue of the waste products is a challenge. Some of these

consumption and reduce the rate of global warming. By weight, concrete makes up the

materials are non-biodegradable and often

largest portion of the solid waste stream.

leads to waste disposal crisis and

Billions of tons of concrete have been used

environmental pollution. The present article

since World War II to construct buildings,

seeks the possibilities of whether some of

bridges, dams, roads, and other structures.

these waste products can be utilized as

When the useful life of these structures is

highway construction materials.

over, the materials from which they were

Use of waste material in construction is an

built will find their way into the waste

issue of great importance in this century.

stream as rubble. Thousands of structures on

Utilization of waste glass and rubber

those installations will be removed. A

particles in concrete addresses this issue.

survey of all installations identified 8,000

The combination of waste glass with

buildings, totaling 50 million square feet, as

portland cement (Glascrete) offers an

candidates for removal. If these buildings

economically viable technology for high

are removed using traditional demolition

value utilization of the industrial waste.

techniques, hundreds of thousands of tons of

Glascrete has attractive appearance due to

waste will be generated and disposed of in

the smooth and colorful glass aggregates,

landfills.

Industrial waste in

exhaustible in nature, its quantity is

highway construction: -

declining gradually. Also, cost of extracting

Introduction: Civilization also produces waste products. Disposal issue of the waste products is a challenge. Some of these materials are not biodegradable and often leads to waste disposal crisis and environmental pollution. The present article seeks the possibilities of whether some of these waste products can be utilized as highway construction materials. Traditionally soil, stone aggregates, sand, bitumen, cement etc. are used for road

good quality of natural material is increasing. Concerned about this, the scientists are looking for alternative materials for highway construction, and industrial waste product is one such category. If these materials can be suitably utilized in highway construction, the pollution and disposal problems may be partly reduced. The following table presents a partial list of industrial waste materials that may be used in highway construction:

construction. Natural materials being Waste product

Source

Possible usage

Fly ash

Thermal power station

Bulk fill, filler in bituminous mix, artificial aggregates

Blast furnace slag

Steel industry

Base/ Sub-base material, Binder in soil stabilization (ground slag)

Construction and

Construction industry

Base/ Sub-base material, bulk-fill, recycling

demolition waste Colliery spoil

Coal mining

Bulk-fill

Spent oil shale

Petrochemical industry

Bulk-fill

Foundry sands

Foundry industry

Bulk-fill, filler for concrete, crackrelief layer

Mill tailings

Mineral processing industry

Granular base/sub-base, aggregates in bituminous mix, bulk fill

Cement kiln dust

Cement industry

Stabilization of base, binder in bituminous mix

Marble dust

Marble industry

Filler in bituminous mix

Waste tyres

Automobile industry

Rubber modfied bitumen, aggregate.

Glass waste

Glass industry

Glass-fibre reinforcement, bulk fill

Nonferrous slags

Mineral processing industry

Bulk-fill, aggregates in bituminous mix

China clay

Bricks and tile industry

Bulk-fill, aggregates in bituminous mix

Material acceptability criteria: -

susceptibility etc., whichever are applicable.

Roads are typically constructed from

There are a large number tests suggested by

layers of compacted materials, and generally

various guidelines/specifications; presently

its strength decreases downwards. For

the performance based tests are being

conventional materials, a number of tests are

emphasized, rather than the tests which

conducted and their acceptability is decided

estimate the individual physical properties.

based on the test results and the

The tests and specifications, which are

specifications. This ensures the desirable

applicable for conventional materials, may

level of performance of the chosen material,

be inappropriate for evaluation of non-

in terms of its permeability, volume

conventional materials, such as industrial

stability, strength, hardness, toughness,

wastes. This is because the material

fatigue, durability, shape, viscosity, specific

properties, for example, particle size,

gravity, purity, safety, temperature

grading and chemical structure, may differ

substantially from those of the conventional

same set-up and be compared. Figure-1

materials. Thus for an appropriate

presents a flow chart to evaluate the

assessment of these materials, new tests are

suitability of industrial waste for potential

to be devised and new acceptability criteria

usage in highway construction. Health and

are to be formed. However, with the advent

safety considerations should be given due

of performance based tests, it is expected

importance handling industrial waste

that the performances of the conventional as

materials.

well as new materials can be tested on a

Suitability of industrial

industrial wastes for its utilization

wastes as highway

in highway construction. The

material: Limited information is available on suitability of individual

following table (Table-2) summarizes the advantages and disadvantages of using specific

industrial wastes in highway construction.

Conclusion: It appears that some of the

construction. However, environmental consequences of

industrial waste materials may find

reuse of such materials needs to be

a suitable usage in highway

thoroughly investigated.

Glascrete: Portland Cement

decrease in particle size. This means that the

Concrete with Waste Glass as

ASR expansion increases with increasing

Aggregates: The partial replacement of natural aggregate by waste glass in Portland cement concrete is studied in this article. As mentioned earlier, the main problem to be confronted here is the alkali-silica reaction(ASR) expansion. The research showed that there are several approaches that can effectively control the expansion of ASR due to glass aggregate, in addition to the conventional approaches used to minimize ASR expansion of regular Portland cement concrete, such as using silica fume and various additives. First, the particle size of glass aggregate was found to have a major influence on ASR expansion. Since the ASR reaction is clearly a surfacearea dependent phenomenon, one would expect the ASR associated expansion to increase monotonically with aggregate fineness. However, there exists a size of the aggregate at which the maximum expansion occurs. This is called "pessimum" size. For aggregate finer than the pessimum size, the ASR expansion decreases with further

fineness of glass particles up to a certain point and then decreases afterwards. Types of glass were found to have a significant effect on the ASR expansion.. Various types of glass aggregate were tested including soda-lime glass (used in most beverage containers), pyrex glass, and fused silica. The maximum expansions of mortar bars made with different glass aggregate types differ by almost one order of magnitude. Window glass, plate glass, and windshield glass were found to cause negligible ASR expansion in test. Colors of glass are also important for ASR expansion. Clear glass (the most common kind in waste glass) was found to be most reactive, followed by amber (brown) glass. Green glass did not cause any expansion. Depending on the size of glass particle, green glass of fine particles can reduce the expansion. This implies that finely ground green glass has the potential for an inexpensive ASR suppressant. The green color comes from added Cr2O3 in the glass. However, when chromium oxide is added directly into the

concrete mix, the ASR expansion of the

suppressing mechanisms of Cr2O3 in green

concrete is not reduced. So, the ASR

glass needs to be further studied.

Rubber Modified Concrete (RMC):

effective to improve mechanical properties

A systematic experimental study was

of the RMC. Three coupling agents:

performed recently for improving strength

PAAM(polyacrylamide), PVA(Pressure

and toughness of rubber modified concrete.

Ageing Vessel) and silane were tested.

Two types of rubber particles of different

Although PAAM is quite effective to

sizes (large and small) were used to study

improve the interface strength between

the size effect on mechanical properties of

rubber particles and cement matrix, it has

RMC. The average size of large particles is

adverse effect on the workability of the

4.12 mm, and the average size of small

RMC when the rubber content is above 10%

particles is 1.85 mm. The test results

of total aggregate by volume. Both PVA and

indicated that particle sizes used in this

silane are very effective in improving the

study has no effect on compressive strength,

compressive strength of the RMC. There is

brittleness and toughness of RMC.

no adverse effect on workability of the

Low water-cement ratio significantly

RMC. PVA is more effective than silane for

increases the strength of rubber-modified

improving the compressive strength of the

mortars (RMM). An 8% silica fume

RMC. The overall results show that using

pretreatment on the surface of rubber

proper coupling agents to treat the surface of

particles can improve properties of RMM.

rubber particles is a promising technique,

On the other hand, directly using silica fume

which produces a high performance material

to replace equal amount (weight) of cement

suitable for many engineering applications.

in concrete mix has the same effect. In general, the bond between rubber particles

The advantages of the RMC :-

and concrete can be enhanced by increasing

(1) The toughness and ductility of RMC are

electrostatic interactions and/or facilitating

usually higher than that of regular concrete,

chemical bonding. In this study, rubber

which makes it suitable for many

particles were pretreated by coupling agents,

applications;

and the method was found to be very

(2) The density of RMC is lower than the

cement plants, RMC makes a fully use of

density of regular concrete;

the high energy absorption feature of the

(3) Comparing with other recycling

rubber particles.

methods, such as using waste tires as fuel in second group as commonly used in traditional cementitious material. The ions The disadvantages of RMC : -

with strong ionic force formed during

(1) The strength of RMC is usually lower

dissociation of alkali metal compound,

than the strength of regular concrete;

promote the disintegration of slag powder

(2) The durability of RMC is not well

and hydration of the ions, and then, such

understood.

ions take part in the structure formation of cement paste, so the cement has properties

Alkali-slag concrete:Alkali-slag concrete is made from

of rapid hardening and early strength gain. For such type of concrete there is less

slag powder and alkali component as main

Ca(OH)2 and high alkali hydrates in

constituents of cementitious material. The

hydration products of cement, in case of

slag powder may be one or a mix of the

high Al/Si ratio, there will be some mineral

following:

of zeolite type resulting in its high resistance

blast furnace slag, phosphorous slag,

to corrosion. Due to perfect pore structure,

titanium-containing slag, manganese slag,

small total pore volume, proper distribution

basic cupola furnace slag, aqueous slag from

of pore diameters, dense structure and good

power plant, nickel slag, silica aluminate.

bond of interface between cement and

The alkali component as an activator

aggregate, the special concrete and concrete

is a compound from the elements of first

with the strength of 20-120 MPa can be

group in the periodic table, so such material

obtained. The concrete mix has a good

is also called as alkali activated cementitious

workability with slump of 0-22 cm without

material or cement. The common activators

water reducing agents.

are NaOH, Na2SO4, Na2CO3, K2CO3, KOH,

The concrete has a high hardening

K2SO4, water glass, or a little amount of

rate with low heat of hydration, consisting of

cement clinker and complex alkali

only 1/2 to 1/3 of that for OPC; its

component; therefore, its activity is more

impermeability is 1.0-4.0 MPa; the frost

than that of compound from the elements of

resistance reached 300-1000 cycles. There is

strong protection of reinforcement with excellent corrosion resistance. It can be used for various building elements and monolithic concrete. For preparing the cementitious material of concrete, only the grinding is required with no calcinations. As for the concrete aggregate, the aggregate

Recycled Concrete Aggregate (RCA):Definition:Recycled concrete originates from

with large content of mud or fine particles,

C&D debris that has been removed from

heavy loam, sea sand, super fine sand,

pavement, foundations, or buildings, and

machined sand,etc. can be used. It is a low

that has been crushed to produce Recycled

cost, energy saving, low resource

Concrete Aggregate (RCA) .Recycled

consumption material, which can promote

concrete aggregates account for roughly 5

the recycling of the waste and make an

percent of the total aggregates market (more

environmental concrete with clean

than 2 billion tons per year) while the rest is

production of cement, environment friendly

being supplied by natural aggregates.

and in good coordination with the environment.

Concrete Building Recycling Flow Process. Physical Properties:Recycled concrete aggregate looks

The lightweight, porous cement mortar attached to recycled concrete

like crushed stone. However, crushed

aggregates causes crushed concrete

concrete has many physical properties that

aggregates to have a lower specific gravity

vary from those of natural aggregates. In

and higher water absorption than

general, crushed concrete particles are more

comparatively sized natural aggregates. The

angular have a rougher surface texture than

lower compacted unit weight of RCA

natural aggregate. Roughly textured,

compared with conventional mineral

angular, and elongated particles require

aggregates results in higher yield (greater

more water to produce workable concrete

volume for the same weight), and is

than smooth, rounded compact aggregate.

therefore economically attractive to contractors. Department Of Transportation

(DOT) specifications have shape

volumetric expansion, in which there is a

requirements for aggregates. For example, at

high probability of internal fracturing and

least 70% of the material should have two or

premature deterioration of the concrete.

more crushed (flat) faces. Increased

Where alkali-silica reactivity is of concern,

angularity of the aggregate increases the

the potential for deterioration should be

asphalt and concrete stability.

evaluated.

Chemical Properties:Concrete recycled from buildings

Chloride ions from marine exposure can also be present in RCA. Because of the

may be contaminated by sulphates from

use of deicing salts as a mechanism to

plaster and gypsum wallboard, which creates

control development of ice on pavement,

a possibility of sulphate attack if the

there is a strong possibility that chloride ions

recycled aggregates used in concrete are

will be present in recycled concrete

accessible to moisture.

aggregate. The presence of chloride ions in

One of the main issues surrounding

Portland cement concrete can adversely

the use of recycled concrete aggregate in

impact the reinforcing steel within concrete.

concrete production is the potential for

Reinforcing steel in the presence of chloride

reaction between the RCA and alkaline

ions will react to form iron oxide or rust. If

water. Alkali-silica reaction results in the formation of iron oxide persists, there is

acceptable levels and to eliminate

a high probability of delamination of the

unnecessary processing cost while providing

concrete structure. Since total elimination of

a quality product.

all deleterious contaminants is not practical, experimentation is required to determine

CRUSHED CONCRETE AGGREGATE Effect of Recycled Aggregate on Concrete Properties:-

Some properties of concrete from recycled aggregates can deviate from those

of comparable concrete mixes with natural aggregates. These differences need not

impair the suitability of recycled concrete. Investigations on crushed concrete from demolition work have proven that it is

ii. Embankment Fill:Crushed rock fill is specified where

possible to produce high-grade aggregate

necessary to control embankment erosion, to

with reused concrete. High quality can be

prevent capillary action from saturating

produced by pre-separation, processing, and

embankments, and to prevent the entrapment

screening of the content for impairing

of water by the embankment. RCA is not

constituents.

commonly used to construct fill embankments because, in most cases, the

Uses of RCA:-

cost of the aggregate will be significantly

i. Granular Base:-

higher than that of common fill. Recycled

A base course is defined as the layer

concrete aggregate in embankments or fill

of material that lies immediately below the

may not make the best use of the high

wearing surface of a pavement. The base

quality aggregates associated with RCA.

course must be able to prevent overstressing

Where no other applications are readily

of the subgrade and to withstand the high

available, RCA can be satisfactorily used in

pressures imposed on it by traffic. It may

this application. It requires minimal

also provide drainage and give added

processing to satisfy the conventional soil

protection against frost action when

and aggregate physical requirements for

necessary.

embankment or fill material. Desirable

Recycled aggregates can be (and are)

attributes of RCA for use in embankments

used as granular base and sub-base in road

or fill include high friction angle, good

construction. In many applications, recycled

bearing strength, negligible plasticity, and

aggregate will prove to be superior to

good drainage characteristics. The design

natural aggregate for use as granular base.

requirements for RCA in embankment

An estimated 85 percent of all cement

construction are the same as for

concrete debris that is recycled is used as

conventional aggregates. There are no

road base due to its availability, low transport cost, and good physical properties.

specific standard specifications covering

drainage or filter media for various

RCA use as embankment or fill and design

applications, including sub-drains for

procedures are the same. Fines should be

buildings, dams, and other engineered

screened out before this type of use.

structures, as well as filters for sewage and

iii. Railway Ballast:-

water treatment. Recycled aggregates are not

Ballast is a select material placed on

commonly used for filter or drainage

the subgrade to distribute the load of the

material because of concerns about

tract and trains to prevent overstressing of

durability, particularly with respect to

the subgrade and to restrain the track

chemical attack from impurities in the

laterally, longitudinally, and vertically under

groundwater or leachate being filtered.

the dynamic loads imposed by trains and the

Recycled fine aggregates are not

thermal stresses induced in the rails by

suitable for use in drainage layers beneath

changing temperatures. Ballast also provides

the pavement because soluble mineral rich

adequate drainage of the track. Ballast

in calcium salts and calcium hydroxide can

produced for use on main lines is generally

be transported with the water as it percolates

governed by standard specifications.

through and plugs sub-drains. If the RCA is

Ballast should meet the gradation

located above such porous drainage systems,

requirements specified in the AREA Manual

the calcium minerals tend to precipitate out

for Railway Engineering, chapter 1, part 2.

of solution and bind to the drainage

It is very desirable that the gravel

structure. The mineral deposits formed are

contain a large volume of crushed stones.

sometimes referred to as portlandite

Otherwise, the ballast will not hold the ties

deposits. Over time, the permeability of the

in place under high-speed traffic, increasing

drainage system can be reduced. If the RCA

maintenance costs. One requirement of good

is intended for use as a drainage layer, then

ballast is that it quickly drain water away

the processed coarse aggregates should be

from the track.

washed to remove the dust and fines.

iv. Drainage and Filter Material:-

v. Concrete Block:-

A relatively small volume of

Concrete blocks are made by mixing

aggregate production goes to provide

Portland cement, sand, and other aggregates

with a small amount of water and then

(sand and various coarse aggregates)

blowing the entire mixture into moulds. The

account for as much as 90% of its

major component material of concrete block

composition. Recycled material such as

crushed concrete and by-products of other

well as the ability to go to the job site.

industrial processes such as blast furnace

Portable plants must be small enough to fit

slag, can be used for some portion of the

on existing roads and under overpasses.

aggregate in block. Concrete block offers an

Demolition project sites may also have

advantage because there is little waste.

space limitations. Recycling concrete at a demolition site is different than recycling on

Technical Issues:The processing of recycled concrete

a paving job or at a stationary plant; the contractor usually has several pieces of

materials is relatively simple, but requires

mobile equipment at the site, mostly

expensive, heavy-duty equipment, capable

excavators with concrete breakers or

of handling a variety of materials. The

pulverizing attachments. Demolished

technology basically involves crushing,

concrete is brought to the crushing operation

sizing, and blending to meet the required

where it is reduced to the maximum size

product mix. Much C&D concrete contains

called for in the specifications. Crushing is

metal and waste materials that must be

usually performed in two steps: a primary

detected and removed at the start of

crusher reduces the larger incoming debris,

processing by manual or magnetic

and a secondary crusher further reduces the

separation. Processing equipment must be

material to the desired particle size.

versatile yet efficient for a handling a

Magnetic ferrous metal recovery can take

variety of materials of non-uniform size or

place after both stages. The two main types

composition.

of equipment are jaw and impact crushers.

The crushing plants can be either a

Jaw crushers are best suited to reduce large

portable type and located on the job site or a

or odd-shaped debris quickly from C&D

stationary plant situated at an existing pit or

projects to a manageable size. Impact

landfill. The main reasons for using portable

crushers are more effective than jaw

plants include the ease of moving the

crushers at freeing rebar encased in rubble.

equipment for cleaning and maintenance, as

CONCLUSION/FUTURE WORK:As natural resources diminish, the demand for recycled concrete aggregate is

likely to increase, making concrete recycling the economically and environmentally preferable alternative to traditional “smash

and trash” demolition. Wherever good

and life cycle cost data for concrete made

natural aggregates are not locally available,

with RCA to assess its durability and

where natural aggregate costs exceed RCA

performance. If additional research supports

costs, or where disposal of existing concrete

the use of concrete buildings – especially

pavement or concrete structures is

barracks – then existing specification should

problematic, concrete recycling should be

be revised to permit and encourage the use

evaluated.

of recycled concrete as aggregate, to

In the future, procedures need to be

conserve existing supplies of natural

developed for the quality control of recycled

aggregates and to reduce the amount of solid

aggregates. Quality materials will also create

waste that must be disposed of in landfills.

competitive markets and higher grade outlets for secondary materials. Concrete

Further research should focus on:

recycling appears to be profitable. In most

(1) The economic aspect of concrete

cases, it can meet demand requirements of

processing and recycling;

lower value product applications such as

(2) The influence of contaminants in the

road base, thereby freeing up higher quality

demolished concrete from buildings;

material for higher value applications. While

(3) The long-term feasibility of recycling;

studies have shown that RCA can be used as

(4) The durability of RCA in new concrete,

aggregate for new concrete, there is a need

and its creep and shrinkage characteristics;

to obtain long-term in-service performance

(5) The use of recycled fines.