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7/23/2019 LOW COST CONSTRUCTION-Selection Of Materials,Use Of Material Composites,Recycling and Reuse of Wastes.

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SELECTION OF MATERIALS, USE OF MATERIAL COMPOSITES ANDRECYCLING OF WASTES IN LOW COST CONSTRUCTION

Ar.Suvarna Lele,Rizvi College Of Architecture,Mumbai

Ar.Sarita Deshpande,NDMVPS College Of Architecture,Nashik.

ABSTRACT : The paper takes a general overview of the significance of selection of materials in

affordable housing to reduce the environmental impact associated with the processing and usage

of source materials. It deals with reducing the energy usage and cost by manufacturing the

materials from the industrial wastes and agro wastes.

INTRODUCTION -

It is a well known fact that about half of the total Investments in our country go to the sector ofconstruction. About 90% of investments in this field come from the private sector. A Large chunkof middle-income group and lower income group invest their life long saving to build their own

houses (as Banks and Financial Institutions generally do not provide them with Finance for wantsof several necessary Documents).It is very essential to help this large segment, by providing them necessary information regardingthe cost saving techniques of construction, for saving their hard earned money. At the same timeprecious, materials like cement and steel can be saved, which can be used for more construction.More over several Government organizations as well as the private centers are trying to introducethe new building materials as well as composites construction Techniques. They have also comeup with several cost saving technologies which go un-noticed and hardly used on actual sites.Cost effective housing is one of the major focus areas in India, where a systematic approach isrequired to construct, cost effective, safe, and environment friendly houses for the general public.

NECESSITY FOR COST REDUCTION

-Increase in construction costs directly affects the economy. This is due to the high cost ofoperations which can be reduced on several levels by use of efficient Planning, cost effectivetechnologies and materials, use of alternate techniques available, Project Management andprocedures improving the procurement and dispute resolution mechanism along with themeasures for initiating more competition and transparency among contractors.The surplus gained from the saving of this surplus cost may be used for the activities such aslabour welfare, implementation of modern machinery and up gradation of technologies andConstruction of More HousesIt becomes necessary to adopt the use of alternative building materials & Constructiontechnologies due to adverse effect of using scarce resources carelessly and eventual rise in thecost of the project. However many practitioners and laymen are unaware of usage of appropriatetechniques in construction. Some State Governments and Agencies of the Central Governmentare propagating these materials and Technologies, but the lack of precision in their specificationsand absence of scheduled of Rates of these technologies, makes the construction based onthese materials and technologies impossible. Many people are privately using the same, but thisis not enough as till the government agencies start using them extensively, they will not bepopular.


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Reused

Locally available low embodied energy

Recyclable biodegradable

Energy efficient pollution preventing

Salvaged Non toxic

SELECTION OF MATERIALS-

To incorporate sustainable design principles the easiest way is to select environment friendlymaterials. Energy conservation can be achieved through every stage of material life cycle. TheLife cycle can be divided into pre-building, building and post building stage. These three stagesindicate flow of building materials through different stages of a building.Pre-building stage mainlyconsists of manufacture which is subdivided in processing, packing and transport. The buildingphase mainly consists of construction, operation and maintenance whilst as the last stage wouldbe disposal where the material can be recycled or reused.1) In Manufacturing Pollution prevention.Some manufacturers carefully consider the modes of production and choose the materials whichare environment friendly. These companies study and revise the methods of producing the goodsto improve their quality, efficiency and reduction of waste. Selecting materials manufactured byenvironmentally responsible companies is encouraging them for pollution prevention.2) Recycling of wastes in Manufacturing The wastes which can be recycled can and used inmasonries whilst as wooden wastes can be used in manufacture of plywood or soft boards.(Courtesy-BMTPC)3) Reducing Embodied Energy and use of Natural materials The total energy required to

produce a material is called embodied energy. The energy is gained by burning of fossil fuels.The greater a materials embodied energy; it requires a greater usage of non-renewable sources.It is therefore advantageous to use materials or composite materials prepared from the wastages.The natural materials such as stones, wood, lime, sand and bamboo can be used in ample whereever possible. The natural materials impact more sustainability to structures as well as they arefriendlier to environment.4) Use of Local material This is one of the very significant aspect of energy saving. Thetransport costs are heavy for the materials which are carried from long distances. Using locallyavailable materials reduce this cost as well as the local materials are better suited to the climateconditions. In any case if the materials are to be transported, they should be transported in asmall volume.5) Energy Efficiency Energy efficiently of a building material can be measured through variousfactors as its R value, shading coefficient, luminous efficiency or fuel efficiency. Energy efficient

materials must reduce the amount of generated energy.6)Use of non-toxic materials The type of materials used, play a significant role in health ofpeople constructing a building and people occupying the building hence to maintain a good airquality inside and outside, the selection of materials should be done with care. There are severalchemicals including formaldehydes, benzene, ammonia, resins, chemicals in insulations, plyboards which are present in furnishings and building material. The health effect of these toxicmaterials must be considered while their selection and they must be used only where-everrequired.Higher air cycling is recommended while installation of materials having volatile organiccompound such as several adhesives, paints, sealants, cleaners and so on.

Material

Selectio

ncriteria


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7) Longitivity, durability and maintenance of a material The materials having longer life areconsidered to be good for construction due to their permanence. The durable material in longterm would be cost effective than the materials which need to be replaced. The lowermaintenance costs naturally save a lot of building operating cost. The materials used in buildingdetermine the long term costs of an operating.8) Recyclability and reusability A material should be available in form which can berecyclable or reusable. Ex the plastics waste can be used for recycling and producing newermaterials. The scrap from steel can be used to manufacture the rcc bars, binding covers andother miscellaneous steel products in building construction.9) Biodegrability A material should be able to decompose naturally whendiscarded. Natural materials or organic materials would decompose very easily. It is also a veryimportant consideration whether a material decomposes naturally or produces some toxic gases.

COMPOSITES AS BUILDING MATERIALS

The compositions of any two materials acting with their strength together are composites. Naturalfiber materials are coming up as excellent substitutes for the prevailing building materials. Fiberslikes jute, sisal coconut, ramie, banana are cheap and environmentally suited as they are madefrom natural fibers. They are also replacing the fiber reinforced plastics.Composites present immense opportunities to replace traditional materials as timber, steel,

aluminum and concrete in buildings. They benefit in resisting corrosion and their low weight hasbeen proved useful in many low stress applications. Each type of composite has its owncharacteristic properties and thus useful for specific purpose.Jute fiber reinforced polypropylene composites, coir fiber reinforcedcomposites, sisal fiber and wollastonite jute pultruded composites are a few to be named. CBRIhas developed MDF composite doors containing coir fiber, cashew nut, shell liquid (CNSL) asnatural resin and Para formaldehyde as major constituents.India has excellent knowledge regarding several binding factors as resins,catalysts and curing processes. It has tremendous potential of becoming a leader in compositetechnology with availability of several natural fibers in ample.The composites can also be glass fiber reinforced or industrial wastebased .Several prefabricated items used in building industry can be manufactured fromcomposites. They can be used to manufacture portable toilets, water storage tanks, outdoor

furnitures, exterior claddings, interior decoration, bath tubs, basins,door and window frames,cabinets and several others.Thus the application in construction vary from cladding to internalfurnishings and the owner highly benefits due to their application because of their light weight,resistance to corrosion and availability in different colours. Pultrusion is most cost effectivemethod for producing composite profiles. It is commercially applicable for light weight corrosionfree structures, electrical non conductive systems and so many other functions.The pultruded items are recognized and recommended in the Global markets.Pultrated sections are well established alternative to steel, wood and aluminium in developedcountries and catching fast in other parts of the world.

RECYCLING OF WASTES

Waste disposal and management is global concern. All the industries produce some kind of

waste in huge quantities. Similarly, managing urban household waste is big issue discussed onall environment related forums. Many agencies and countries worldwide are exploringpossibilities to re-cycle waste materials in many different applications. Construction is one of theprime activities identified to receive re-cycled waste in variety of form and materials. Using wastematerial in the construction as replacement to some other material also reduces the cost ofconstruction of the building.Type of solid Industrial waste which can be recycled-Fly ash (105 mil. tons/annum)Coal mine wastes (50 mil. tons/annum)Lime stone waste (18 mil. tons/annum)


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Blast furnace slag (11 mil. tons/annum)Iron ore tailings (10.5 mil. tons/annum)Copper mine tailings (4 mil. tons/annum)Marble dust (6 mil.tons/annum)Red mud, lime sludge, phospho-gypsum, zinc tailings, kiln dust, gold mine tailings etc(Source: Morchhale, et al J. of Rural Tech. 2 (2) 2005)

The waste material or materials generated from waste are two categories. In the firstcategory it is the wastage of building materials which is consumed or put to use whereas in thesecond category industrial waste or byproduct is processed or recycled to be used as a productor material for building. This second category is the point of study in this case.Large quantities of wastes are produced in process of manufacturing. If properly thought about,these materials can be recycled or reused in some other forms.Construction with the application of various building materials produces tremendous waste. Ageand durability of a particular material would determine its capacity to be reused. Very durablematerials like stone, timber have many useful years of service left when the structure where theyare used is decommissioned. Every other aspects like, wooden frames, plumbing frames andeven bricks can be reused. The broken pieces of flooring materials, glazed tiles can also be put toreuse. There might be possibility of reusing the steel reinforcements in 115 walls, using the brickwastages in coba or the tiles in mosaic works.Building materials and Technical promotion council is working towards the recycling of waste

materials acquired from industries.Most common and popular material for waste re-cycling is steel. Engineering industries

produce huge amount of scrap steel. Many rolling mills accept this waste and re-roll this wasteinto reinforcement bars, binding wires and other miscellaneous steel products used in buildingconstruction. It is commonly used in construction in rural areas and for petty constructions. Thispractice is not acceptable to most of the structural consultants since many times composition ofraw material going into these rolling mills is not known and questionable. As architects we mustinsist on testing of each batch of such reinforcement steel received for use.

By recent estimate, thermal power plants in India today produce more than 85 million tons offly ash. Disposal of fly ash is therefore seen as big environmental issue. Fly ash that is industrialwaste from thermal power plants is pushed as additive to concrete by many environmentprofessionals. Technique of adding fly ash to concrete is tried and tested. It is found safe to addcertain percentage of fly ash to the concrete without compromising the strength of concrete. This

results into good amount of saving on cost of cement and sand.Fly ash is also used with clay as additive to make building blocks and bricks. In fact, in areas

close to thermal power plants making fly ash bricks is developing into big industry. Similarly,units producing prefabricated construction elements not directly used in buildings, such as: Lightand fence polls, manhole covers, road curbs and median blocks, etc. are consuming hugequantities of fly ash in their products.

Wood scrap or shavings and waste from saw mill and plywood factories is effectively put touse by manufacturing recomposed boards from it. Waste material which is in the form ofparticles, wood dust, shavings, etc. are hot-pressed to form a board by adding urea / phenylformaldehyde as adhesive or binder. They form particle and fiber boards of various densities orpre-laminated boards made by covering the faces of such boards with decorative laminate ordecorative or commercial veneer.

Bagas is another waste product used in the same manner as wood or timber waste.

Bagas is waste from sugarcane. After the juice is extracted from sugarcane in the sugar mill thewaste plant material is bagas. It is fibrous in nature and still has enough moisture content in it toprevent disintegration. Amongst the many possible uses tried for bagas, making boards forfurniture and partition panels in the manner mentioned in previous paragraph is one of theestablished products. Bagas is hot-pressed adding urea/phenyl formaldehyde based binder oradhesive to create boards of various thicknesses and densities. The resultant product iscomparable to any other particle boards of similar thicknesses and densities.

Similar types of boards are also produced using plastic waste, particularly shreds of thinpolyethylene bags (popular as carry bags). Success of this product will be a boon to waste


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management efforts as these bags and other plastic products being non-biodegradable arebiggest headache for waste treatment.

In the other category, many other waste products of construction process itself arealready absorbed within the same building or on some other site. To list a few i) Broken flooringmaterial is many times used to create crazy pattern flooring in outdoor areas and verandas.ii) Waste glazed tiles are used for making waterproof floor covering referred to as china mosaic.iii) Steel reinforcement waste is used as reinforcement in 115 thick brick walls.iv) Broken and waste bricks are used for Brick bat coba in toilets and on terrace.v) Waste from stone floors dressing is used for marble mosaic tiles and also in stone creteplaster.vi) Wooden packaging crates discarded by industries are used for making shelves and otherfurniture.In this way we can innovate and put to use a lot of waste material from construction and otherindustries as replacement for new materials. This practice of using waste material for productiveuse can help reduce the cost of construction to quite an extent.Research institutions of BMTPC have developed a large number of alternate and constructionsystems based on use of agro-industrial wastes.Waste Commercial product Traditional resource Energy saved %

1. Bagasse -Bagasse-polymer- Timber fibres 30%(Sugar mills) bonded boards (in insulation board)2. Corn cobs- Corn cobs-cement Timber, polymer 40%(Corn mill) bonded boards3. Sisal fibre- Sisal fibre-polymer/ Asbestos fibre,- 20-15%(Sisal plant) cement bonded Timber4. Coir fibre- Coir fibre-cement Asbestos- 10%(coir industry) roofing sheet & panels5. Rice husk Rick-husk- cement Resin (PF or UF)- 20%(Rice mill) building board bonded particleboard timber6 Ground nut - Ground nut hulls- Resin-bonded- 20%hulls (Oil mills) cement building board particle board timber

7. Jute fibre - Jute-fibre-polymer Timber, metal 10%Jute mills) bonded panel;door and window8. Cotton waste- Cotton-lint-cement Gypsum, timber- 25%(courtesy-BMTPC presentation)

LIFE CYCLE THINKING

Buildings are interdependent with nature over time. Relative to our own individual life-spansbuildings as artifacts of human endeavor can last a very long time. Each building constructed can beregarded as infrastructure for the future as well as a historical record of our society, our economyand how we perceive our relationship with nature. From the day it is opened until well after thoseresponsible for its creation are dead a building's design, materials, energy requirements, and itswaste stream provides a built environment that people will construct their lives within and around.

As a building has a life cycle, so does a building material. Construc tion materials are very oftencomposites made up of many different types of raw materials. The mining, manufacturing,use, mainte nance, reuse, recycling and disposal of every building material have importantenvironmental ramifications. This story of a building's or a material's accumulation ofenvironmental impact is called its life-cycle environmental performance.


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LIFE-CYCLE ASSESSMENT

Describing the environmental impact of a building can be thought of as telling a story about thecombination of all of the environmental impacts of its constituent materials, of theconstruction process, of its operation and its refurbishment and eventual demolition. Thecomplex web of interdependent natural systems in which impacts accumulate determine theeffect a building has. Similarly, each mate rial has a story that describes the origin of all of itsraw materials, the resources required for processing, transportation, manufacturing,packaging, storage, delivery, use, maintenance, reuse, recycling or disposal. Each storydescribes not only the resources required to make the building or material, but theenvironmental impacts at each life-cycle stage.. One approach that makes understanding thesecomplex life-cycle stories easier is a process of evaluation called life-cycle assessment (L.CA). AnLCA considers

extraction, processing and transportation ofrawmaterials; production, transport and distribution of resulting products;

use, reuse and maintenance; recycling and final disposal

The simple depiction of the life cycle is as follows

TAKE USE DISPOSE

INPUTSOUTPUTS IMPACTS

Building life cycle

Raw material extraction, materialproduction

Production of constructionproducts

Construction and rebuilding

Use and maintenance

Demolition

Reuse and recycling

Disposal

LAND

EXST BUILDING

SANITATION

INFR.

TRANSPORTATI

ONINFR.

ENERGY

MATERIALS

RESOURCE

DEPLETION

PHYSICAL

DISRUPTION

CHEMICAL

POLLUTION

SOLID WASTE

BUILDUP

LOST

BIODIVERSITYFLOW

EMISSION TO

AIR

EMISSION TO

SOIL

ALTERED

LANDSCAPE

NOISE,

VIBRATION

TEMPERATURE

STOCK


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NATURAL ENVIRONMENT

Fig. 2 Building life-cycle considerations. Life-cycle thinking requires us to consider the storyof the accumulated environmental loading and associated impacts of a building material and

building. Environmental loads and impacts are associated with the type and quantity of inputs to amaterial or building, the processes and use of material and building, the type and quantity ofoutputs from processes and use, and the nature of the receiving environments. Non-life-cyclethinking considers only how to take, use and then dispose of material, treating nature as merely thesource of our materials and, after they are used, a sink for our wastes.

CONCLUSION

Product selection can begin after the establishment of project-specific environmental goals. Theenvironmental assessment process for building products involves three basic steps. - Research

Evaluation and Selection. A life cycle assessment (LCA) is an evaluation of the relative"greenness" of building materials and products. LCA addresses the impacts of a product throughall of its life stages

The affordable housing should be seen in relation with the selection of ecological and economicalmaterials, usage of recycled wastes and composites which can considerably affect the economyand ecology of construction.

REFERENCES

Sustainable building design manuel by TERI Vol 1 &2LEED India Reference Guide ver 1

BMTPCwww.greenspec.comwww.buildinggreen.com
http://www.greenspec.com/http://www.buildinggreen.com/http://www.greenspec.com/http://www.buildinggreen.com/


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