Thursday, 22 August 2019

Metal Recycling from Construction and Demolition Waste (CDW)


All construction companies now promote 'sustainable materials management' where they recycle and reuse certain CDW. This is mainly done to reduce the overall construction cost and the total aggregate demand for new building materials for a construction project.


CDW can be mainly divided into two categories: metals and non-metals. Wood, concrete, asphalt, bricks, glass, and plastics come under the non-metals category. On the other hand, ferrous and non-ferrous materials come under the metal category.


Around 95% of the total recovered metal from any construction project is actually steel. Besides, around 1-2% aluminum (mainly from doors and windows), 1-2% copper (mainly from piping and wires), and around 1% stainless steel (from structural supports) can be also recovered from Construction and Demolition (C&D) projects.

(Source: https://www.environment.gov.au/system/files/resources/b0ac5ce4-4253-4d2b-b001-0becf84b52b8/files/case-studies.pdf)


Steel is the easiest metal product to recycle from any C&D site as it can be segregated with minimal effort. And steel products actually produce almost zero waste. Besides, some surplus steel products such as tubes, rebars, pipes, claddings, and internal structural supports can be  reused with  little or  no reprocessing.



Recycling of steel products also has an environmental advantage, since there are  few environmental impacts due to minimal reprocessing. A majority of the steel products recovered from C&D projects can be sandblasted to remove coatings and base painting layers. Then, primer can be applied to use it for a new project. However, engineers do need to inspect and approve their properties and strengths before using it.



Other non ferrous metals, such as copper and aluminum, can be  melted to remove any impurities. They can finally be molded into new products to use in new construction sites.



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