Abstract
The growth of the Indian construction sector is expected to result in a significant demand–supply gap with respect to construction materials such as sand, limestone, and aggregates. Additionally, the vast quantity of unprocessed Construction and Demolition (C&D) waste pose serious problems in some places, particularly in residential, institutional, industrial or commercial construction hotspots. While several waste quantification methodologies have been proposed in the literature, the quantification of waste generation in India is inadequate. This inadequacy can be attributed to the lack of appropriate hierarchical control mechanism, absence of a common C&D waste estimation method, and the lack of C&D waste processing knowledge among generators, collectors, operators, regulators, and the general public. The C&D Waste Management Rules 2016 were introduced to ensure organized collection, storage, transportation, treatment/processing, and disposal of C&D waste in India and fix responsibilities of all stakeholders for management of C&D waste. This comprehensive research attempts to analyze the existing legislation and challenges, and proposes an information framework for organized collection, storage, treatment/processing, and disposal of C&D waste. The C&D waste processing mechanism, potential application of recycled C&D waste products, its limitations, and the best practices of C&D waste management in India are important constituents of the proposed framework.
Introduction
Construction and Demolition (C&D) waste refers to any waste comprising building materials, debris, and rubble resulting from construction, repair, re-modeling, and demolition of civil structures such as houses, bridges, roads, dams, large building structures, and other infrastructure (MoEFCC, 2016). C&D waste usually comprises inert and non-biodegradable material such as concrete, brick aggregates, tiles, plastic, wood, glass, metals, excavated soil and rock particles, etc. (CPCB et al., 2017). The quantities and composition of C&D waste may vary according to the type of structure and the scale of construction, demolition, or renovation activities. The typical composition of C&D waste in India is given in Figure 1.
Typical Construction and Demolition (C&D) waste composition in India (CPCB, 2017).
Global C&D waste generation reached 3.0 billion tonnes annually in 2012 and this trend is increasing continually. China leads the worldwide generation of C&D waste, exceeding 1 billion tonnes in 2012 and up to 1.13 billion tonnes in 2014 (Akhtar and Sarmah, 2018; Lu et al., 2016). However, in India it is estimated to be 10–12 million tonnes annually, which on per capita basis is around 8.29 to 9.95 kg capita-year−1. These figures represent gross underestimation when compared to the C&D waste generation reported by other countries (110–842 kg capita-year−1) and result in an inadequate policy framework to address C&D waste management in India (Ram and Kalidindi, 2017). According to some estimates, India generated about 0.53 billion tonnes of C&D waste in 2013, thus making it the second largest generator of C&D waste in the world (Akhtar and Sarmah, 2018; Manuja et al., 2016). C&D waste contributes about 30–50% of the total solid waste generated worldwide (Akhtar and Sarmah, 2018; Galvez-Martos et al., 2018; Hoornweg and Bhada-Tata, 2012; Islam et al., 2019; Manuja et al., 2016; Tam and Lu, 2016). The provision of housing and associated infrastructure plays an important role in countries undergoing rapid development and urbanization. India’s housing stock increased from 250 million units in 2001 to 330 million units in 2011 (TERI et al., 2016). The Indian construction sector has grown at an average annual growth rate of 10% over the last decade, with its contribution to gross domestic product (GDP) increasing from USD 23 billion in 2001–02 to USD 62 billion in 2011–2012, equivalent to 8% of India’s GDP. In terms of employment, the construction sector forms the second largest segment in India’s economy after agriculture, providing employment to about 35 million people (TERI et al., 2016).
The key demand drivers for construction industry in India are population growth, urbanization, and income growth (TERI et al., 2016). India is rapidly moving from an agriculture-based nation to an industrial and services-based economy. With 34% of Indian population living in urban areas, India is one of the least urbanized countries in the world. Yet it has the second largest urban population in the world (Gupta et al., 2015; The World Bank Group, 2019). As of 2012, about 70% of the buildings that will exist in 2030 were yet to be built (ASCI and NRDC, 2012). The under-supply of housing has become particularly acute in cities and the built-up area in India is expected to increase exponentially due to large-scale domestic and industrial growth (ASCI and NRDC, 2012; CSE, 2011). The rapid urbanization has not only resulted in new construction, but also in the demolition of older, shorter buildings to make way for the newer and taller buildings (CSTEP, 2016). The stream of C&D waste generally results from the construction, renovation, and demolition of buildings, road, bridges, dams, and other structures (Wu et al., 2014).
Material consumption in Indian construction sector
The construction sector was the second largest sector in India in terms of material consumption in 2007. With an increase in absolute material consumption by more than one billion tonnes, the construction sector was the fastest growing sector between 1997 and 2007 (TERI et al., 2016). At such a growth rate, the construction sector is expected to surpass the agriculture sector by 2020 and become the sector with the highest material consumption in India. Sand/fine aggregates (for concrete and mortar), stone/gravel (for coarse aggregate), soil (for brick production), iron and steel (for bars and rods), and limestone (for cement production) are the dominant materials used in the Indian construction sector (TERI et al., 2016).
The rise in construction activity has placed high demands on construction materials, with the demand for sand being particularly high (CSTEP, 2016). The estimated annual consumption of construction materials in India stood at 750 million tonnes (MT) of sand, 242 MT of limestone, 2 billion tonnes of stone (aggregate), and 350 million m3 of soil in 2018 (MoHUA and NITI Aayog, 2018). The total annual demand for sand in Karnataka alone was estimated to be 26 MT in 2014 and it is expected to grow up to 56–81 MT per year until 2030 (CSTEP, 2016; Sunder and Asundi, 2015). India is the second largest producer of cement in the world, accounting for about 6.3% of global cement production (Department of Industrial Policy and Promotion, 2011; TERI et al., 2016). At current growth rates, cement production in India is expected to increase up to 4–7 times by 2050 and India may exhaust its considerable limestone reserves by 2030 (IEA and WBCSD, 2018; IGEP, 2013). In order to meet the demand of limestone for steel and chemical industries in India and the resulting shortage of limestone for cement production, the net cement imports in India increased from 1 MT in 2000 to 4 MT in 2010 (IGEP, 2013). Furthermore, the cement industry is one of the largest emitters of CO2, and accounts for approximately 7% of total CO2 emissions in India (IEA and WBCSD, 2018).
C&D waste generation in India and its quantification
In terms of waste generation, the Indian construction sector can be broadly classified as bulk generators and retail/small generators of C&D waste. Infrastructure and real estate sectors constitute the bulk generators of C&D waste. Construction and repair of roads, bridges, flyovers, etc. are classified as infrastructural development and account for about one-half of the construction sector (Gayakwad and Sasane, 2015; TERI et al., 2016). The real estate segment and small C&D waste generators account for another half of the construction sector and consist of housing, industrial, institutional, and commercial building construction, and demolition of unauthorized building structures. Small and medium commercial enterprises and individual house building activities usually cover the retail or smaller waste generators (Gayakwad and Sasane, 2015).
C&D waste is generated during the entire life cycle of a project that involves construction, usage/maintenance, and demolition (Wu et al., 2014). Therefore, the three primary waste generation activities are construction of new buildings, renovation or maintenance of existing buildings or infrastructure, and demolition of older buildings (Wu et al., 2014; Youcai and Sheng, 2017). However, in order to push the efforts towards reusing and recycling of C&D waste, it is useful to classify C&D waste according to the source of generation. C&D waste can be classified into four categories depending on its source.
Construction/Renovation waste: The typical causes of waste generation during construction of new buildings include timber formwork, wet finishing, concrete work, masonry work, and material handling, which account for 30%, 20%, 13%, 13%, and 10% of total waste generation, respectively (Wu et al., 2014). Construction waste can be estimated based on construction area, material consumption, and on the urban population output ratio (Youcai and Sheng, 2017). Civil and infrastructural works usually involve projects that support a society, such as roads, bridges, highways, dams, airports, etc. The public buildings involve a large construction area and complex renovation processes, and multiple material consumption, often generating significant amounts of waste due to their large volume and longer duration of work (Wu et al., 2014; Youcai and Sheng, 2017). Wu et al. (2014) reported that these structures are often omitted or intentionally excluded from quantification. Building demolition waste: The demolition of older buildings that are used for industrial purposes results in the generation of industrial C&D waste, which possesses the characteristics of both hazardous waste and C&D waste. Appropriate processing should be adopted to reduce the environmental impact of hazardous wastes (Youcai and Sheng, 2017). Nearly all demolished structures end up as waste except some materials such as wood, metal, etc. which have a mature secondary market (Poon et al., 2004a). Selective demolition or deconstruction of structures is considered as an effective solution to reduce and recycle demolition waste (BMTPC, 2018; Kourmpanis et al., 2008; Wu et al., 2014). The relatively complex characteristics of such waste make the estimation of demolition waste difficult. Thus, the mixed recyclable waste generated during demolition of a building should be taken to a recycling center while the non-recyclable material should be transferred to a landfill (Kourmpanis et al., 2008). The demolition waste can be assessed by assigning empirical waste generation coefficients to a demolition activity or using construction budget estimates (Youcai and Sheng, 2017). Land/road excavation waste: The waste generated during the excavation of land, including topsoil and deep soil, for new construction activity constitutes a significant fraction of C&D waste. The excavation of concrete or asphalt roads during repair generate concrete blocks and asphalt as waste (Youcai and Sheng, 2017). Building materials waste: The waste generated during the production process of building materials such as cement, concrete, etc. also contributes to the total C&D waste (Youcai and Sheng, 2017).
Several methods have been developed to quantify C&D waste at regional and project levels. One such method developed by the Technology Information Forecasting and Assessment Council (TIFAC) is based on the waste generated during different activities (CPCB, 2017):
40–60 kg m-2 of new construction; 40–50 kg m-2 of building repair; 300–500 kg m-2 of building demolition.
Empirical estimations may be used for C&D waste quantification under certain specific conditions. However, some other useful methodologies have been developed to quantify C&D waste using direct/indirect measurements, waste generation factors/multipliers, building/material lifetime estimates, economic indicators, etc.
Site Visit (SV) method: This method involves the direct or indirect measurement of C&D waste by undertaking visits to construction or demolition sites. Direct measurement requires weighing the waste or measuring its volume on-site. Indirect method employs truck load records to estimate the volume of waste generated on a construction/demolition site or a landfill (Kartam et al., 2004; Poon et al., 2004b; Wu et al., 2014). Generation Rate Calculation (GRC) method: GRC method is a common technique of waste generation estimation by using the waste generation rate for a particular activity unit. Several alternative parameters such as per capita multiplier, financial value extrapolation, and area-based calculations can be employed to obtain waste generation (Wu et al., 2014). The waste generation rate principle has been used to estimate building-related C&D waste generation in cities like Chennai (Ram and Kalidindi, 2017). Lifetime Analysis (LA) method: Constructed buildings are ultimately demolished and become demolition waste. Hence, the amount of demolition waste must equal the mass of constructed structure and can be estimated by assuming reasonable lifetime of buildings and materials, and accounting for the material consumption and typical waste factors for construction materials (Poon, 1997; Wu et al., 2014). Classification System Accumulation (CSA) method: This method of calculating waste generation is based on the GRC method. The primary improvement over the GRC method is that this methodology uses a classification system which provides a platform for quantifying different specified material (Wu et al., 2014). Variables Modelling (VM) method: C&D waste generation depends on variables such as economic indicators, construction areas, working conditions, etc., which help in the simulation of C&D waste generation using variables modelling (Wu et al., 2014). Some studies have adopted this approach to understand the time-dependent accumulation rate of C&D waste (Kern et al., 2015, Sáez et al., 2014).
The precise quantities of C&D waste generation in India are uncertain (CPCB, 2017). This can be attributed to various factors.
Lack of a common C&D waste estimation method for all municipalities and Urban Local Bodies (ULBs) leads to an absence of a C&D waste generation database (CPCB, 2017). C&D Waste Management Rules 2016 explicitly define the duties of waste generator, service providers/contractors, local authorities, as well as State and Central Pollution Control Boards in waste generation and processing hierarchy (MoEFCC, 2016). The Rules mandate streamlined functioning of each stakeholder and also ensure appropriate cooperation among different stakeholders. However, an absence of adequate C&D waste monitoring mechanisms at various hierarchical levels of management often leads to non-accountability of all stakeholders. Lack of appropriate processing knowledge among generators, collectors, and especially the general public leads to mixing of C&D waste with other types of municipal solid waste (MSW) and subsequent deposition in landfills, wetlands, and open spaces around urban centres for real estate development (CPCB et al., 2017; CSE, 2014). This prevents the quantification methodologies from exact quantification of C&D waste that is generated, resulting in variable estimates. The mixing of C&D waste with MSW also renders the MSW unusable for composting or energy recovery purposes. Varying pace of developmental activities and developmental plans with respect to land use in cities magnifies the problem of C&D waste in cities with major construction projects under government initiatives like SMART Cities Mission (CPCB, 2017).
C&D waste management legislation in India
C&D waste in India was traditionally considered as a component of MSW and has therefore been addressed on a very limited scale in the legislations governing MSW management. However, increasing quantities of C&D waste mixed with MSW creates major problems at the MSW processing facilities. The proper management, reuse, and processing of C&D waste has been the focus of various governmental agencies since 2010 (BMTPC, 2018). A chronological review of key waste management legislations, guidelines, and standards concerning C&D waste is useful in tracing the evolution of C&D waste management practices as well as the continual challenges posed by C&D waste in India (Table 1).
Chronological outline of important Construction and Demolition (C&D) waste management legislations in India.
The C&D Waste Management Rules 2016 were implemented in India with primary focus on management of C&D waste based on the principles of reuse and recycling, and ensuring planned processing and disposal of C&D waste.
The C&D Waste Management Rules 2016 explicitly define the duties of the waste generator, service provider and its contractors, local authority, State Pollution Control Board (SPCB) / Pollution Control Committee (PCC), State Government/Union Territory Administration, Central Pollution Control Board (CPCB) and the Central Government in an organized waste management mechanism. Schedule I of the Rule specifies detailed criteria for site selection for storage and processing or recycling facilities for C&D waste. Schedule III of the Rule stipulates a specified timeframe for planning and implementation of the provisions provided therein by various enforcing bodies/authorities. The Rule provides for reporting of any accident in a C&D waste processing or treatment or disposal facility to the local authority.
Manuja et al. (2016) identified some limitations and recommended measures to improve upon the operative part of the C&D Waste Management Rules 2016.
A list of expert institutions and civil society groups which can be utilized for consultation or creation of a sustained system of Information, Education, and Communication (IEC) for C&D waste may be included in the legislation for public interest. The possibility of utilizing C&D waste as a cover material for sanitary landfill has not been proposed in the C&D Rules of 2016. An action plan for utilizing C&D waste as landfill cover can be a viable disposal method of unprocessed C&D waste. To avoid arbitrary user charges, the location and composition of C&D waste may be used as the basis for calculation of fixed charges payable by the waste generator for collection, transportation, processing and disposal of C&D waste.
Some other measures which can be adopted to ensure effective management of C&D waste include setting up of specific targets to achieve recycling of C&D waste, tax exemption on usage of recycled concrete aggregate to encourage use of recycled C&D waste, and investing efforts in IEC campaigns to spread awareness on reuse and recycling of C&D waste (Ramanathan, 2018).
Indian C&D waste management framework
The predicted demand growth of construction materials is expected to cause significant material supply problems in India (TERI et al., 2016). Supply bottlenecks have already affected prices and construction schedules in some parts of the country. The construction sector is particularly vulnerable to price instabilities since material costs typically account for more than 60% of the total cost of a building in India (TERI et al., 2016). The acute demand for recycled aggregates in the housing and road sectors to reduce the demand–supply gap, and the need to check resource depletion due to excessive sand mining are some other factors of immediate concern. On the other hand, large construction projects under government initiatives to fulfill housing demands and commercial infrastructure projects adds to the enormous quantities of C&D waste that remain unprocessed.
The development of a framework for organized collection, storage, processing and disposal of C&D waste using the principles of reuse and recycling is an important step towards solving the dual problem of material shortage and waste accumulation (CPCB et al., 2017). An understanding of a typical C&D waste processing system is essential to establish best practices within the information framework.
C&D waste processing mechanism
The activities regarding C&D waste management, processing and re-use in India have made steady progress after the issuance of C&D Waste Management Rules by MoEFCC in 2016. Several stringent by-laws and guidelines have been formulated by the municipalities, but their enforcement has its limitations (BMTPC, 2018). The Rules mandate the segregation of C&D waste into concrete, soil and other fractions by the waste generator and directs the local authority and its contractors/transporters to collect and transport C&D waste in a segregated manner (BMTPC, 2018; MoEFCC, 2016). The primary activity at any C&D waste storage or facility involves the recovery of any reusable/recyclable item such as metal, wood, or plastic in the supplied C&D waste.
The processing of C&D waste can be done either at a centralized processing facility or at the project site itself, i.e. in-situ processing. In-situ waste processing is suitable for projects generating more than 0.1 MT of C&D waste. Smaller projects can utilize mobile C&D waste crushing and segregation equipment which are generally available for processing capacities of up to 5 tonnes per day (TPD) (BMTPC, 2018). Waste generators which generate ≥ 20 TPD or 300 tonnes per project of C&D waste in a month are mandated by the operative Rules to segregate C&D waste into four fractions, i.e. concrete, soil, steel/wood/plastic, and brick & mortar. Such large waste generators are required to pay for the processing and disposal of C&D waste in addition to storage, collection, and transportation charges (MoEFCC, 2016). A typical C&D waste processing unit in India constitutes the following steps (Development Alternatives, 2017; Hiete, 2013):
primary segregation of C&D waste into metal/plastic/wood/other recyclable items, big concrete blocks of size 425 mm or above, and mixed C&D debris of smaller size; removal of contaminants such as asbestos, gypsum, heavy metals, and tar from waste streams; primary screening of mixed C&D debris; primary crushing; secondary crushing; secondary screening (into coarse and fine aggregates); dust removal; sand washing (to separate clay and sand & silt).
The choice of C&D waste processing techniques adopted in a processing unit depends on the type and composition of incoming C&D waste, local site conditions, economics of waste processing, and the desired output of recycled aggregate materials. Secondary screening during waste processing effectively segregates the waste material into four streams (BMTPC, 2018):
fine waste of −5 mm size fraction, which is typically collected and used for landscaping and filling of low-lying areas; material of −40 mm +5 mm size, which is fed to Vertical Shaft Impact (VSI) crusher after magnetic separation to be used for the manufacture of sand; material of −65 mm +40 mm size, which is fed to the cone crusher after magnetic separation; material of size +65 mm, which is fed to the impact crusher.
The typical outputs of C&D waste processing after washing and stacking of produced coarse and fine aggregates are (BMTPC, 2018):
coarse aggregates of sizes −40 mm +20 mm, −20mm +10mm, and −10mm +5mm; fine aggregates/sand of size fraction −4.7mm +0.150mm; fine waste for landscaping or filling of low-lying areas; rejects.
The recycling of C&D waste reduces the demand on new resources, cuts down on transport and production energy costs, and utilizes waste which can otherwise be lost to landfills (Tam and Tam, 2006). The inert material sorted out of C&D waste prior to processing is used as soil cover on dumpsites in Indian cities like Lucknow and inorganic waste is used in Meerut for granular sub-base layer of pavements (TERI, 2019). Plastic material in C&D waste has been used to pave roads in Bangalore, Kolkata, and some places in Kerala, but is known to cause secondary microplastic pollution on subsequent breakdown (NIVA, 2019; Siddiqui, 2013). However, the aggregates obtained by recycling of demolished concrete (recycled concrete aggregates) are presently being utilized as aggregates only in granular base or sub-base applications, embankment construction, and earth construction works. Recycled aggregate is often not considered a suitable raw material for high quality product applications such as aggregate for structural concrete. The primary reason for this is that the quality of recycled concrete aggregate is lower than the quality of natural aggregate, which is an important consideration for a raw material being used in structural concrete application. When the demolition concrete is crushed, a certain fraction of mortar and cement paste from original concrete remains attached to stone particles in recycled aggregate. This attached mortar is the main reason for lower quality of recycled aggregate compared to natural aggregate (Marinkovic et al., 2010). Density of recycled aggregate is decreased by up to 10% compared to density of natural aggregate (Poon and Lam, 2008). While water absorption for natural aggregate generally ranges from 0.5% to 1.0% (Marinkovic et al., 2010), it varies from 3.5% to 9.2% for coarse recycled aggregate (López-Gayarre et al., 2009; Rahal, 2007; Xiao et al., 2005), and from 5.5% to 13% for fine aggregate (Evangelista and Brito, 2007; Yang et al., 2008). This leads to high water absorption by fine recycled aggregate, thus making its quality control difficult.
The energy demands for recycling C&D waste to produce recycled concrete aggregate are comparable to the production of fresh aggregate from crushing of stones. However, the recycling process is energy-intensive when compared to extraction of natural river aggregate for use in concrete production. Therefore, an analysis of environmental effects resulting from concrete production using recycled aggregate is crucial. Such an assessment of environmental impacts is generally undertaken in a Life Cycle Assessment (LCA) study. LCA has already been applied to assess the environmental impact of building materials, structural elements, and whole buildings (Buyle et al., 2013; Li, 2006; López-Mesa et al., 2009; Ortiz et al., 2009; Wu et al., 2005). Some research has also been conducted on the environmental impact assessment of end-of-life scenarios such as landfilling, recycling and incineration of C&D waste (Ortiz et al., 2009; Wittmaier et al., 2009). However, modest effort has been undertaken to systematically assess the environmental impacts associated with management and utilization of C&D waste in construction works (Butera et al., 2015). Further, such studies are still to be conducted under Indian conditions, taking into account region-specific generation rates and coefficients.
Usage potential of C&D waste processing products
The earliest instances of C&D waste reuse in the world dates back to the post-Second World War period of aggregate shortage for rebuilding cities. Recycled aggregates produced from construction debris were used to the extent of 20–50% in concrete, blocks, pavers, etc. (BMTPC, 2018). The advent of advanced technology has led to rapid generation of direct produce from C&D waste recycling which includes fine aggregate/sand, Recycled Concrete Aggregate (RCA) of variable sizes, Recycled Aggregate (RA) of variable sizes, and manufactured soil/fine waste.
Manufactured soil is used as a substitute of excavated soil for landscaping purposes. Fine and coarse aggregates are used as raw material for ready-mix concrete (RMC) plants and construction sites. C&D waste processing output can also be used in the manufacture of downstream products like bricks/blocks/tiles, paver blocks, prefab concrete slabs, park benches, compound walls, fence posts, underground cable covers, drain/manhole covers, etc. Fine and coarse aggregates serve as a good material for road construction and an appropriate mix of aggregates can be supplied according to market demand for buildings and road construction. The use of recycled aggregate materials is usually preferred over primary aggregate material in road construction applications as it allows reduction in the thickness of asphalt layer (Hiete, 2013). However, the achievable prices of recycled C&D waste are less than the price of primary material with similar mechanical, physical, and chemical properties.
The prices of primary or virgin aggregate material generally covers production cost, transportation cost, profit for aggregate producer, and an aggregate extraction tax in some countries (Hiete, 2013). The share of transportation cost in the total cost is more decisive for recycled aggregate due to their inherently lower value. Transportation costs become even higher in case of a stationary C&D waste processing plant, which result in higher preference to mobile processing plants for recycled aggregates. Further, it has been reported that processing costs per tonne of C&D waste strongly decrease with the capacity of stationary waste management plants due to economy of scale (Duran et al., 2006). Therefore, a trade-off between mobile and stationary C&D waste processing plants is essential to balance the reduction of processing costs in larger, stationary plants and the reduction of transportation costs in mobile processing plants, as well as to ensure cost efficiency.
Several testing centers in India have conducted validations based on compressive strength of concrete upon partial replacement of natural fine/coarse aggregate with recycled fine/coarse aggregates. Bureau of Indian Standards (BIS) in 2016 revised IS 383 to permit the use of recycled fine/coarse aggregates in plain concrete, reinforced concrete, and lean concrete (IS 383: 2016). Similarly, Central Road Research Institute (CRRI) validated the suitability of recycled fine/coarse aggregate for road construction. Indian Roads Congress (IRC) permitted the usage of recycled C&D waste products in road construction and issued guidelines for use of construction and demolition waste in roads sector (IRC, 121: 2017).
Best practices in Indian C&D waste management
Civic bodies, industries, and other organizations have become increasingly aware of the problems of C&D waste and have begun to undertake some measures for C&D waste processing. Several C&D waste management projects that have been implemented across various locations in India can be reviewed and analyzed for best practices (BMTPC, 2018; Development Alternatives, 2017).
The first C&D waste processing plant in India was commissioned in 2010 at Burari in North Delhi under a Public Private Partnership (PPP) agreement between North Delhi Municipal Corporation and ILFS Environmental Infrastructure & Services Ltd (IEISL) for treatment of 500 TPD C&D waste on a pilot basis. The plant currently operates at a processing capacity of 2000 TPD and demonstrates an economically feasible business model that could be adopted across India. Both dry and wet processing have been adopted to recycle and process about 95% of incoming C&D waste into aggregates, manufactured sand, and finished products such as paver blocks, concrete bricks, drain slabs, etc. The produced materials meet Bureau of Indian Standards (BIS) codes for construction applications and have been recommended for preferential procurement by public agencies. Three other C&D waste recycling plants have been commissioned by the Government of NCT of Delhi to cover all zones of Delhi. A second plant of capacity 500 TPD at Shastri Park in Delhi started operations in 2016. Ahmedabad Municipal Corporation (AMC) started a C&D waste processing plant of capacity 1100 TPD in 2014 under a PPP agreement with Amdavad Enviro Projects Pvt. Ltd (AEP). The plant currently operates at 300 TPD and processes C&D waste into aggregates, which in turn are used to prepare finished products such as paver blocks, concrete tiles, pre-cast toilets, park benches, etc. The preferential procurement policy of AMC facilitates the use of these products in government infrastructure projects. A C&D waste recycling plant was set up by M/s Enzyme India Pvt. Ltd in 2014 for recycling 150 TPD of C&D waste at the project site of ‘Re-development of East Kidwai Nagar, New Delhi’. The plant worked on PPP agreement with 100% buyback of recycled products by National Buildings Construction Corporation (NBCC). The recycled produce such as fine/coarse aggregates and manufactured soil were used as fill material and in the manufacture of downstream products like RMC, bricks, tiles, and blocks. A non-governmental organization named ‘Youth for Unity and Voluntary Action (YUVA)’ undertook recycling of 1500 tonnes of C&D waste generated from City and Industrial Development Corporation of Maharashtra Ltd (CIDCO)-YUVA Building Center (CYBC) in Kharghar, Mumbai during the period 2002–2006. The C&D recycling demonstration manufactured building materials such as bricks, blocks, concrete, sand substitute, and coarse aggregates.
Conclusion
The rise in population, urbanization, and income growth in India during the last decade has led to the generation of enormous quantities of waste from Indian cities. In order to meet the demand for housing and infrastructure, the constructed area is projected to increase by five times its current size to about 9.6 billion m2. The corresponding requirement of construction material has made India the second largest cement producer in the world, accounting for about 6.3% of global cement production. Infrastructure and real estate projects constitute the bulk generators of C&D waste. Building construction/renovation, demolition, land/road excavation, building material production are some important sources of C&D waste generation. Several useful methodologies have been proposed in literature to quantify C&D waste using different techniques.
The two-faced problem of meeting the demand for construction materials as well as processing of large quantities of unprocessed waste has led to the development of important C&D waste management measures in India. Waste management legislations in India have emerged as a natural consequence of the need to ensure effective C&D waste management, culminating in the formulation of a separate C&D Waste Management Rules 2016 by the government. However, due to lack of C&D waste processing awareness among the regulators, operators, and the general public, the potential for usage of recycled products in the Indian construction sector is still untapped. The C&D Rules of 2016 were followed by several guidelines and revisions in important material usage standards for concrete (IS 383: 2016, IRC 121: 2017). It is important to comprehend the best practices of C&D waste management adopted by cities like Delhi and Ahmedabad and reproduce their business models at other operational and proposed C&D waste recycling plants across India.
Footnotes
Acknowledgement
The authors would like to acknowledge the support of Er. Upendra Chugh, an IIT Delhi alumnus, for providing valuable inputs on the final draft of this research article.
Declaration of conflicting interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.
