Chapter 1- Introduction of Construction and Demolition Waste

1.1. DEFINITION

    Recycling of Construction and Demolition Waste (CDW) is an important practice that refers to collection, re-use and recycling of the waste generated from Construction Industry. It is also an important environmental initiative because it reduces the demand for landfill space and demand on raw materials. The Construction and Demolition Waste Management includes the onsite separation, collection, re-use and recycling of the solid waste materials generated due to construction, maintenance, retrofitting and demolition activities of the building structures across the country. The recycling and re-use of the CDW materials must be done onsite as much as possible, after that the separation and sorting of that waste should be done for the transportation/hauling of the collected waste materials. The on-site recycling is a good technique as it can reduce the amount of the waste materials. Since the construction and demolition wastes consist of different waste materials viz., demolished concrete, reinforced steel bar, brick pieces, wooden units, plastic pipes, glass, metals, others. It must be necessary to sorting and separately collection of the waste on-site.

1.2. NECESSITY OF CDW RECYCLING

   Rapid economic growth leading to urbanization and industrialization is generating waste, which is adversely affecting the environment. The percentage of India's population living in cities and urban areas increased from 14% at the time of independence to 30%. Projections for building material requirement by the housing sector indicate a shortage of aggregates to the extent of about 55,000 million m3. An additional 750 million m3 of aggregates would be required to achieve the targets of the road sector. There is also a huge demand for aggregates in the housing and road sectors, but there is a significant gap in demand and supply. Estimated waste generation during construction is approx. 40 kg per m2 to 60 kg per m2. Similarly, waste generation during renovation and repair work is estimated to be approx. 40 kg per m2 to 50 kg per m2. The highest contribution to waste generation comes from the demolition of buildings. Demolition of pucca (permanent) and semi-pucca buildings, on average generates between 300kg per m2 and 500 kg per m2 of waste, respectively. It is estimated that the construction industry in India generates about 10-12 million tons of waste annually.

The needs of the recycling of the waste generated in construction and demolition works in construction industries are also summarized below: -

 To fullfill the demand of the shortage of the aggregates in various construction works by supplying the recycled aggregate from the CDW materials in the construction industry.

 The shortage of space for the landfill sites needs the recycling of the huge amount of waste generated every day, as it can reduce the need of landfill space.

 The huge amount of this waste if mix with the municipal solid waste or sewage, it becomes very difficult to recycle and affects our environment. It becomes a major cause of the environmental pollution. Hence it must be stored separately for further hauling and recycling.
 Thousands of tons of recyclable materials from construction and demolition (C&D) activities that are sent to landfill every day. It contains valuable materials which can be recycled and we can get more and more benefits from recycling these waste.

 The sustainable and economical development of our country depends upon the construction industry too (Green Construction). Hence, the recycling of these waste can improve the economy by minimizing the cost of the construction materials.

1.3. THE SCOPE OF CDW RECYCLING

      The scope of the recycling of the concrete waste is very wide. The successful recycling of CDW materials can minimize the cost of construction in the construction industry. As recycling of these wastes can produce the various construction materials, precast units, concrete products, brick blocks, etc., from the construction and demolition waste materials. The main thing is the benefits that will earn from the re-use and recycling the concrete wastes. Everyone wants to dispose off the demolished materials from their land after the demolition of the buildings and they also waste their money for the removal of all the demolished building materials. But if there are proper recycling techniques for these waste materials and which can be affordable for each and every people regardless the economic status, then it will become very easy to recycle the construction and demolition wastes. The introduction of the Portable CDW Machine can be one of the best technique for the recycling the concrete waste in urban areas as well as in rural areas. The project includes the description, working, design and all functions of Portable CDW Machine. Also, the objective of the recycling of the construction and demolition wastes is to increase the cost effectiveness of construction and to provide better method of recycling of these waste materials for the Green Construction. The project under concern deals with the study of the recyclable materials from the construction and demolition wastes generated , recycling techniques, recycling machines and recycling plant of these wastes and also experimental analysis of the recycled materials have been done for their suitability in construction works.

1.4. BENIFITS OF CDW RECYCLING

     The proper construction and demolition waste management can provide a better facilities and cost effectiveness in the field of the recycling of these waste. There are some benefits of the recycling the CDW materials: -

i. Recycling of the concrete waste will avail us various construction materials, concrete blocks, bricks and other valuable materials at lower cost.

ii. The production of the recycled materials reduce the gravel mining as the cost of mining & the manufacturing of the materials are increasing day by day.

iii. Recycled concrete is lighter per unit volume, which means less weight per cubic meter, which results in a reduced cost of construction materials, hauling and overall project.

iv. Onsite Reuse of bricks, stones slabs, timber, conduits, piping railings etc. can be done to the extent possible and depending upon their condition.

v. Easily Sale/auction of material which can’t be used at the site due to design constraint or change in design.

vi. Plastics, broken glass, scrap metal etc. can be used by recycling industries. These only needs sorting of the CDW and separate collection.

vii. Rubble, brick bats, broken plaster/concrete pieces etc. can be used for building activity, such as, leveling, under coat of lanes where the traffic does not constitute of heavy moving loads.

viii. Fine material, such as, sand, dust etc. can be used as cover material over sanitary landfill. These are the additional benefits.

ix. Processed C&D waste can be used for road and embankment construction too.

x. Finer grade can be molded into blocks and slabs with appropriate binder.

xi. Sustainable & economic development of country is the major benefit which will come from the development in CDW recycling techniques.

xii. Recycling techniques /processes enable one to understand the importance of the concrete waste recycling. Awareness among the people will increase and they

xiii. Recycling of the CDW, which is a major portion of the solid waste generated, will result in a large reduction of the solid waste.

xiv. Environmental pollution can be reduced by using these recycling techniques.

xv. Recycling can save the cost and the fresh construction materials and improve the Green Construction, energy saving and decreased use of natural resources.,etc.
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