Code No:TMS150Price:RsRs2400/-Category:Environment & Habitat
Year of Publication : 2001
Table Of Contents : INTRODUCTION- Indian Construction Industry, Waste from Construction Industry, Re-Use/ Recycle for Sustainable Development. WASTE FROM CONSTRUCTION INDUSTRY- Source of Waste, Constituents of Waste, Quantum of Waste from Construction Industry. MANAGEMENT OF WASTE FROM CONSTRUCTION INDUSTRY IN INDIA- Practices in Construction Operation, Practices in Demolition, Waste Management Practices, Waste Disposal by Landfill, Recycling of Construction Waste in India. RECYCLING OF WASTE FROM CONSTRUCTION INDUSTRY- Recycling of Concrete and Masonry Waste, Properties of Recycled Aggregate, Recycled Aggregate Concrete, Quality of Recycled Aggregate, Recycling of Bituminous Material. REVIEW OF RECYCLING OPERATIONS IN OTHER COUNTRIES- UK, Denmark, The Netherlands, France, Germany. FEASIBILITY OF RECYCLING UNIT- Demand-Supply Equation, Feasibility Analysis, Environmental impact of Recycling, Constraints to Recycling of Construction Wastes. PREFERRED OPTIONS- Recycling of Demolition Waste arising from Disaster, Relevance of Recycling in Hilly Terrain, Evaluation of Recycling Techniques, Managing Barriers to Recycling. RECOMMENDATIONS, IMPLEMENTATION AND ACTION PLAN- Recommendations, Implementation & Action Plan, Expected Benefits, Spin Off Benefits. ANNEXURES
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Indian Construction Industry is highly employment intensive and accounts for approximately 50% of the capital outlay in successive 5-Year Plans of our country. The Projected investment in this industrial sector continues to show a growing trend. Construction activity leads to generation of solid wastes, which include sand, gravel, concrete, stone, bricks, wood, metal, glass, plastic, paper etc. The management of construction and demolition waste is a major concern for town planners due to the increasing quantum of demolition’s rubble, continuing shortage of dumping sites, increase in transportation and disposal cost and above all growing concern about pollution and environmental deterioration. Central Pollution Control Board has estimated current quantum of solid waste generation in India to the tune of 48 million tons per annum of which waste from Construction Industry accounts for 25%. Management of such high quantum of waste puts enormous pressure on solid waste management system. Construction waste is bulky and heavy and is mostly unsuitable for disposal by incineration or composting. The growing population in the country and requirement of land for other uses has reduced the availability of land for waste disposal. Re-utilization or recycling is an important strategy for management of such waste. Apart from mounting problems of waste management, other reasons which support adoption of reuse/ recycling strategy are- reduced extraction of raw materials, reduced transportation cost, improved profits and reduced environmental impact. Above all, the fast depleting reserves of conventional natural aggregate has necessitated the use of recycling/ re-use technology, in order to be able to conserve the conventional natural aggregate for other important works. |
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Recycling of demolition waste was first carried out after the second world war in Germany to tackle the problem of disposing large amounts of demolition waste caused by the war and simultaneously generate raw material for reconstruction. Considerable research has been carried out in U.S.A, Japan, U.K, France, Germany, Denmark etc. for recycling concrete, masonry & bricks, bituminous and other constituents of waste from Construction Industry. These studies have demonstrated possibility of using construction waste to substitute new materials of recycling. In view of significant role of recycled construction material and technology in the development of urban infrastructure, Technology, Information, Forecasting and Assessment Council (TIFAC) has commissioned a techno-market survey on ‘Utilization of waste from Construction Industry’. The focus of the present study is housing /building sector and road construction segment. |
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Waste is generated at different stages of construction process. Waste during construction activity relates to excessive cement mix or concrete left after work is over, rejection/ demolition caused due to change in design or wrong workmanship etc. Estimated waste generation during construction is 40 to 60 Kg. per sq. m. Similarly, waste generation during renovation/ repair work is estimated to be 40 to 50 kg/sq. m. The highest contribution to waste generation is due to demolition of buildings. Demolition of Pucca and Semi-Pucca buildings, on an average generates 500 & 300 kg/ sq.m. Of waste respectively. Concrete appears in two forms in the waste. Structural elements of building have reinforced concrete, while foundations have mass non-reinforced concrete. Excavations produce topsoil, clay, sand, and gravel. This may be either re-used as filler at the same site after completion of excavation work or moved to another site. Large quantum of bricks and masonry arise as waste during demolition. These are generally mixed with cement, mortar or lime. Stone arises during excavations or by demolition of old buildings. Metal waste is generated during demolition in the form of pipes, conduits, and light sheet material used in ventilation system, wires, and sanitary fittings and as reinforcement in the concrete. Metals are recovered and recycled by re-melting. Timber recovered in good condition from beams, window frames, doors, partitions and other fittings is reused. However, wood used in construction is often treated with chemicals to prevent Termite infestation and warrants special care during disposal. Other problems associated to wood waste are inclusion of jointing, nails, screws and fixings. Bituminous material arises from Road planning, water proofing compounds, Breaking and digging of Roads for services and utilities. Other miscellaneous materials that arise as waste include glass, plastic material, paper, etc. The total quantum of waste from construction industry is estimated to be 12 to 14.7 million tons per annum. Quantity of different constituents of waste that arise from Construction Industry in India are estimated as follows: |
Constituent |
Quantity Generated in million Tons p.a. (Range) |
Soil, Sand & gravel |
4.20 to 5.14 |
Bricks & Masonry |
3.60 to 4.40 |
Concrete |
2.40 to 3.67 |
Metals |
0.60 to 0.73 |
Bitumen |
0.25 to 0.30 |
Wood |
0.25 to 0.30 |
Others |
0.10 to 0.15 |
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Contractor executes construction project on a labour contract basis or on turnkey basis. Small housing projects, executed by owners, are predominantly executed on labour contract basis and strict supervision is required to control waste generation during construction process. Typically, waste generation ranges between 5 to 7%. In larger projects, where execution is on turnkey basis or through one’s own team of professionals, material wastage is within 3%. Services of demolition contractor are taken when old building is to be demolished due to deterioration of the building or to make way for construction of a new building. Demolition contractor specializes in planned deconstruction so that recovery of good material can be maximized for re-use. Recovery rate varies from 25% in old buildings to as high as 75% in new buildings. Items recovered during demolition are sold in the market at a discount with respect to price of new material. Sometimes, Wood carvings and Marble structures are recovered from old buildings, which fetch very good price as Antique piece in Domestic/ Export market. Although, the responsibility of removing the waste is primarily of the builder or the owner, it is usually assigned to the demolition contractor. Items, that cannot be re-used, are disposed off to landfill site. |
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Management of solid waste is the responsibility of Municipal Bodies or health officers. They notify landfill sites for disposal of solid waste. Hard core material from demolition operation is required for land fill activities to provide daily cover over domestic waste, bulk fill capping, hardstandings etc. Some Municipal Corporations require demolition waste for their landfill activities, while others want to minimize it to prolong useful life of landfill sites. However, all respondents are unanimous that in the long run, recycling of waste from construction industry is necessary in view of limited landfill space and increasing quantum of demolition waste. Different constituents of waste are not segregated prior to disposal. Municipal Authorities incur cost of Rs 60 to 80 per ton of waste, but presently no charge is levied by them on the owner or builders. Builders/ Owners bear the cost of transportation, which at present range between Rs. 250 to Rs 500 per truckload depending on the distance of demolition site from landfill area. Though directives exist for disposal of waste to landfill areas, presently penal action against violators is practically not taken. |
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Presently management of waste from construction industry in India, comprise of the following elements:
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Basic method of recycling of concrete and masonry waste is to crush the debris to produce a granular product of given particle size. Plants for processing of demolition waste are differentiated based on mobility, type of crusher and process of separation. There are three types of recycling plants Viz. Mobile, Semi-Mobile and Stationary plant. In the Mobile plant, the material is crushed and screened and ferrous impurities are separated through magnetic separation. The plant is transported to the demolition site itself and is suited to process only non-contaminated concrete or masonry waste. In the semi-mobile plant, removal of contaminants is carried out by hand and the end product is also screened. Magnetic separation for removal of ferrous material is carried out. End product quality is better than that of a Mobile unit. Above plants are not capable to process a source of mixed demolition waste containing foreign matter like metal, wood, plastic, hardbound etc. Stationary plants are equipped for carrying out crushing, screening as well as purification to separate the contaminants. Issues necessary to be considered for erection of a Stationary plant are: plant location, road infrastructure, availability of land space, provision of weigh-bridge, provision for storage area etc. Different types of crusher are used in recycling plant namely jaw-crusher, impact crusher, impeller-impact crusher. A comparison of their features, relative advantages and disadvantages are summarized in Table 5 (PP65). Different types of sorting devices and screens are used for separating contaminants from end-product and grading the recycled product in various grain sizes. Vibrating screens, star screens or disc-separators are used for removal of impurities. Three main processes used for purification are:
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Properties of recycled aggregate have to be compared to those of natural aggregate to evaluate its suitability for applications in Construction Industry. Density of recycled aggregate is lower and water absorption is higher than that of original aggregate. This is primarily due to mortar adhering to the concrete and higher porosity of bricks that are recycled. Table 3 (PP30) compares physical and mechanical properties of recycled aggregate with natural aggregate. |
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Recycled aggregate can be used as general bulk fill, sub-base material in road construction, fills in drainage projects and for making new concrete. While using recycled aggregate for filler application, care must be taken that it is free of contaminants to avoid risk of ground water pollution. Mixed debris with high gypsum, plaster, should not be used as fill. Use of recycled aggregate as sub-base for road construction is widely accepted in most countries. It is possible to use crushed concrete as coarse fraction of gravel in sub-base for road, but crushed brick is not suitable owing to its high bitumen requirement and high void content. For using recycled aggregate to make new concrete, water absorption of the recycled aggregate must be determined in the laboratory to decide the mix design. Use of fine recycled aggregate for concrete making is not recommended as it increases the water demand and lowers the strength and durability of concrete. Pre-soaking of recycled aggregate is suggested to take care of high water absorption so that concrete of uniform quality is produced. |
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Concrete made from recycled aggregate has lower compression strength caused by the bond characteristic of recycled aggregate and the fresh mortar. Fraction of less than 2mm of recycled aggregate bring about the largest reduction in strength of recycled aggregate concrete (RAC). Fine aggregates also reduce frost resistance of recycled aggregate concrete. Drying shrinkage of recycled concrete is higher than that of concrete with conventional aggregate. Workability of concrete decreases with increased portions of demolition waste. Upto 30% of natural coarse aggregate can be substituted, by coarse recycled aggregate, without any impact on the quality of concrete. Problem associated with use of recycled aggregate, for manufacture of new concrete, is the possibility of contaminants in original debris passing into new concrete. Such impurities reduce the strength of the concrete. Waste glass is a problem because it is alkali reactive with cement paste under wet conditions. Organic substances like wood, textile fabrics, paper and other polymeric materials are unstable in concrete. Paints may entrain air in concrete. Test results of aggregate properties and concrete properties prove repeatedly recycled concrete to be both durable and of good quality in all respects. Therefore, existing concrete structures, in addition to providing an aggregate source for the immediate future, may continue to generate an adequate supply of aggregate for concrete construction in the more distant future after once being recycled. Recycled aggregate of best quality for concrete production is obtained when it is graded. Although there are no standards drawn up in India for recycled aggregate and recycled aggregate concrete, specification drawn in other countries are useful as a guideline. Annexure III includes some of the specification drafted in Japan. |
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Recycling of Bituminous material, commonly practiced in other countries, can be carried out by hot or cold mixing technique either at location or at a central asphalt mixing plant. It offers benefits like saving in use of asphalt, saving of energy, reduction in aggregate requirement etc. Cold in-situ recycling is done by pulverizing road to a certain depth, mixing in cement, bitumen emulsion or foamed bitumen and compacting. This recycling process is more applicable to lighter traffic roads. In Hot in-situ recycling, the upper layer of the road is pre-heated and the asphalt is loosened by milling devices. It is mixed together with recycling agent and the mixture is spread along the road and compacted. In India, recycling of bituminous material is not practiced. In developed countries, special purpose machine has been built, which carry out the total process of hot in-situ recycling. It is important that the project for recycling is properly evaluated to ensure that the potential benefits of hot in-place recycling are realized. |
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Recycling of waste from Construction Industry is carried out in U.K, France, Denmark, Germany, U.S.A, Japan, etc. The proportion of different constituents varies from country to country depending upon the material used for construction and the building technology. However, demolition and construction waste recycling operations relate to segregation, crushing and grading of hard materials. Such operations may be based at fixed locations or may be moved from site by site to service particular projects. The salient features of recycling operations in different countries can be summarised as follows: The Regulatory framework in Denmark has significantly helped it to improve recycling of waste from Construction Industry. Before demolition of the building, the owner of the structure has to apply for permission by filling in detailed form in which he has to identify each constituent and estimate the quantity likely to arise. Simultaneously, he has to define the disposal strategy. He has to also identify the waste carrier and environmental problems anticipated during waste disposal along with methodology to control it. After demolition takes place, different materials have to be transported separately other wise it attracts a price penalty or even refusal for movement of material. The disposal of waste to landfill is taxed at high rates, while there is no tax on material sent to recycling. Records are computerized based on the application received and the returns provided by the transporter. Thus, the authorities can audit the whole disposal process for waste arising from demolition. Netherlands has developed specifications covering recycled material to be used as aggregate in concrete. Dutch Government has imposed stiff charge on disposal of waste to landfill sites. This charge has risen by seven times since 1988. A database on all recycling operations has been built. Dutch Government targets to achieve recycling of 90% of the available demolition and construction waste by the year 2000. To achieve this, the Government is promoting demonstration project, specifying the use of recycled material in public work and is providing financial support to recycling operations The technology adopted in Denmark is simple and labour intensive, while the plants in Germany incorporate number of machines. |
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Non awareness of recycling possibilities is one of the main barriers due to which waste is disposed to landfill. Absence of technology for recycling is another major hurdle for recycling of construction waste. Once technology is known, availability of feedstock in sufficient quantities and of requisite quality is another bottleneck for its widespread use. The acceptability of the recycled material is hampered due to poor image associated with recycling activity in India. Customer specifications do not permit use of materials recycled from Waste. Cost of disposal of waste from construction industry to landfill has a direct bearing on recycling operations. High dumping costs induce diversion of waste for recycling. |
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Creating awareness & dissemination of information is essential to build public opinion and instill confidence in favour of recycling option. There is a need to create market for the recycled products by involving the Construction Industry to use recycled materials in their construction projects. Development of standards for recycled materials would provide producers with targets and users an assurance of quality of material. Standards formulated in other countries can be a guideline for development of specification in our country. Commissioning of a pilot plant as a demonstration unit can help in breaking barriers against recycling of construction & demolition waste. Imposition of charge on Sanitary landfill can induce builders and owners to divert the waste for recycling. Government support and commitment is vital for development of recycling industry. Development of policy supported by proper regulatory framework can provide necessary impetus. It will also help in data compilation, documentation and control over disposal of waste material. Low returns from investment in recycling units can be offset by providing suitable fiscal incentives by the Government for gestation period. These are warranted in the long-term interest of reducing pollution and conserving valuable resources. Environmental impact of recycling has both advantages and disadvantages. Advantages are reduced disposal of waste to landfill sites and reduced mineral extraction. Disadvantages are problems of Noise and Dust emission and risk of ground water pollution. The problem of noise can be managed by using silencers and providing acoustic enclosures while water spray is useful to control dust emission. |
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Based on evaluation of the technology, review of Waste Management practices in India and other countries, and assessment of constraints to recycling option in the country, following recommendations along with implementation & action plan are proposed : |
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There is a pressing need to create awareness about the problems of waste management and the necessity to adopt reuse and recycling options for waste from Construction Industry. It is recommended that Seminars, Conferences and Workshops be held in different parts of the Country. Simultaneously, other media should also be exploited to create an environment in favour of Recycling. Interpretation on the above may result in bringing out publication/ brochures highlighting the short and long term benefits of recycling strategy and indicating case histories of utilisation of construction industry waste, especially in India. Circulation of these brochures especially in construction industry research departments, field/design organisations in Central/ State government may generate sufficient confidence for promotion/ adoption of recycling strategy for their works. Equally important is the need to generate sufficient Database regarding efficacy and field adoptability of the recycling strategy in the country. A coordinated action should be taken up by NGO’s, environmentalist, government offices and industry representatives. |
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The recycling technology for construction waste has to be established on a pilot scale in India. It is recommended that pilot scale plant for producing recycled aggregates is established and application of recycled aggregates in different construction activities is demonstrated. Central Road Research Institute or Central Building Research Institute may be involved to put up a pilot plant and establish use of recycled aggregate in road and building construction. |
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The most common application of recycled aggregate in other countries is its usage as sub-base material in construction of roads. At first, recycled aggregates should be tried for this application. Produce from Pilot plant should be evaluated by Central Road Research Institute for using it as sub-base for Road. Accordingly, specifications for Road construction should be modified so that recycled aggregate is used in this application. |
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Manufacturers of Crushers, screens and separating equipment should be involved to provide necessary equipment for the recycling unit. Presently, manufacturers of such equipment in India are suppliers to Natural Aggregate Industry. Suitable modifications, as may be required, can be carried out by manufacturers to their product for processing Construction Waste. Manufacturers of Crushers, Screens and material Handling Equipment should take up this work. |
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Quality standards/ codes of Practice regarding various aspects of product control and acceptance criteria for use of recycled aggregate in recycled aggregate concrete and other works should be formulated. This would help in setting a target product quality for producers and assure the user of a minimum quality requirement, thus encouraging him to use it. Specifications drawn in other countries like Japan, Netherlands, Germany etc. can be a useful guideline. BIS in coordination with Construction Industry, Research Laboratories involved in producing recycled aggregate should take up this work. |
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The Construction Industry should formulate guidelines to encourage use of recycled products in construction projects. This would encourage the incorporation of recycled product in specifications and create market demand. Association of Builders, Experts from Construction Industry in consultation with experts/ scientists from research laboratories should undertake this work. |
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Government should formulate and implement policy for Management of waste from Construction and other Industries. It should clearly set out goals for recycling of Waste as a means of reducing pollution and conserving valuable resources. Government of India in consultation with State governments, Pollution Control Boards should formulate this plan. |
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The present framework for disposal of waste needs to be strengthened and improved. To realise the full potential of all materials suitable for recycling, a process similar to that carried out in Copenhagen should be adopted. In this approach, all the demolition and construction wastes have to be accounted in terms of re-use, recycling and disposal. Such an elaborate system can be developed and implemented in two steps. In the short term, requirement of applying for permission for demolition process with mandatory requirement to provide details of the projected quantities, types and disposal routes can be introduced. In the long term, along with permission for demolition, commitment of segregation of constituents of waste and recycling should be submitted. Government of India should undertake this work in coordination with Construction Industry, Municipal Corporations and Pollution Control Boards. |
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Based on success of demonstration unit, Municipal Authorities of Metropolitan cities should put up facility for recycling of construction and demolition waste adjacent to their landfill sites. The waste from Construction Industry can be used in this plant for making recycled aggregates. Charges should be imposed on disposal of construction waste to landfill site. This is to induce the builders/ owners to divert the waste to recycling. Municipal Corporation Authorities of Metropolitan Cities should take up this work under guidance of agency, which has put up the pilot plant. If necessary, assistance from foreign consultants/ experts may also be taken. |
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