The recent controversy over sand mining has put the spotlight on the need for recycle and reuse of waste generated during the building of new structures.
The construction industry in India is booming, already a 10 per cent of the GDP, and is growing at an outstanding rate of 10 per cent over the last ten years as against the world average of 5.5 per cent per annum. Almost 70 per cent of the building stock in India is yet to come up, the built up area is expected to swell almost five times from 21 billion sq ft in 2005 to approximately 104 billion sq ft by 2030. Buildings are the core of all our demand — water, energy and material but it also creates waste.
Waste generated in the construction, maintenance and disposal phase of the building is categorised as construction and demolition waste. Globally, cities generate about 1.3 billion tonnes of solid waste per year and this volume is expected to increase to 2.2 billion tonnes by 2025, says a 2012 report on solid waste by the World Bank. Building materials account for about half of all materials used and about half the solid waste generated worldwide.
There is no documented quantification of amount of construction and demolition waste being generated in India. The Municipal Corporation of Delhi’s 2012 estimates show that Delhi generates close to 4,600 tonnes of C&D waste daily, while 1,600-2,000 tonnes per day generation is indicated as per the transport arrangements of the MCD, which points at illegal dumping.
According to the Centre for Science and Environment estimates, since 2005, India has newly constructed 5.75 billion sqm of additional floor space with almost one billion sqm in 2013 itself. If according to Technology Information, Forecasting and Assessment Council’s thumb rule a new construction generates 40-60kg of C&D waste per sqm, then taking an average of 50 kg per sqm India must have generated 50 million tonnes of C&D waste this year alone and about 287 million tonnes over last eight years. This estimate is only for new construction. Demolition and renovationwork related waste of the older stock will be extra and waste generated per sqm of demolition is 10 times the waste generated by construction. If C&D waste generated by infrastructure projects like road, dams, is also added India is already drowning in this waste.
The recent controversy over sand mining has put the spotlight on the need for recycle, reuse and substitution of naturally sourced building material to reduce demand for naturally sourced construction material. In 2012, the Supreme Court made the environmental impact assessment process under the Environment Protection Act, 1986, mandatory for all mining sites to regulate mining of minor minerals and to ensure environmental management. On August 5, 2013, the National Green Tribunal declared sand mining with environmental clearance illegal.
Research carried out by premium institutes like Central Building Research Institute, National Council for Cement and Building Materials and IIT-Kanpur, have established that C&D waste can be recycled and adsorbed in construction activities itself. It can be used for making bricks and paver blocks, can also be used to partly replace natural sand and stone in concrete.
The MCD has set up a C&D waste recycling plant at Burari under a public-private partnership model with IL&FS Environmental Infrastructure & Services Limited. This is a pilot project and has capacity of recycling 500 tonnes per day.
Globally cities have initiated legal process to maximise reuse of C&D waste in construction. Effective recycling rate in Korea is 36 per cent with a target of 45 per cent by 2016. The Netherlands has found that 80 per cent of its C&D waste is bricks and concrete that can be recycled. Singapore recycles 98 per cent of its C&D waste.
India needs to start promoting the reuse this ever increasing mound of C&D waste it generates.
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