There are a number of contaminants to be found in demolition debris, and many of these will have a deleterious effect on the ease of recycling and/or reuse of salvaged materials, or the quality of performance of the final products. Even materials which are valuable in their own right are considered contaminants if they are mixed with the main material being reclaimed. The following ^ list identifies potential deleterious contaminants in demolition waste:
glass wood putrecibles/organic compounds compressible materials i.e. plastics, paper etc. gypsum sulphates trace elements deleterious to health trace elements deleterious to the setting and strength development of Portland cement lead salts calcium oxide/magnesium oxide chlorides old blast furnace slag.
It is essential to know the history or composition and level of contamination of materials before they are reused. Extra vigilance is required in the use of industrial demolition debris, especially with respect to:
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Clients want premium products for their money - that is they want the highest quality possible in every respect. Salvaged and recycled materials from demolition sites are usually regarded as secondhand products, possibly impaired in some way, with reduced performance levels and possibly reduced aesthetics. Specifiers tend to express a range of views, both positive and negative about recycled and reclaimed materials, as outlined in Section 5.6. Unfortunately, the attitude of secondhand is second best prevails over these more positive attitudes and opinions. It is also often difficult, despite the preference of a designer, to prove or guarantee that client and or insurer requirements can be met in terms of:
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