Civil Engineering Reference
In-Depth Information
amount of mineral components that are clean and chemically inert. However,
this trend is already viewed with some trepidation, since such waste may
be contaminated with paint, surface treatment of substances or even heavy
metals that can leach out and contaminate water and soil.
Oliveira (2002) concluded in his research that building wastes consisting
solely of concrete waste, mineralize the water and change the soil, i.e.,
are non-inert, suggesting that these wastes are classified as non-hazardous
and non-inert. Hansen (1992) also mentions that the CDW may contain
components, that are considered as toxic from an environmental point of
view. So, it seems that such waste can be classified as inert or non-inert,
depending only on its origin and constitution.
One particular point that demonstrates the importance of CDW is its
increasing share of total municipal solid waste (MSW). Several surveys
indicate that CDW currently represents around 50% of the total MSW produced
in Brazilian cities, with an average rate of generation around 0.52 tonne/
habitant/year (Cabral, 2007). In the European Union, there is no consensus
about CDW generation but it represents approximately 22-49% of the total
waste generation, representing 450-970 million tonnes of CDW generated
per year, which corresponds to 0.9-2.0 tonne/habitant/year (Solis-Guzman
et al., 2009; Sonigo et al., 2010; Sáez et al., 2011).
According to Sáez et al. (2011), France and luxembourg generate 5.5 and
15 tonnes/habitant/year, respectively. Germany and Ireland generate between
2 and 4 tonnes/habitant/year, whereas the rest of the European countries
generate between 0.2 tonnes/habitant/year (Norway) and 1.9 tonnes/habitant/
year (United Kingdom). In the United States, the generation of CDW during
90 years was 0.43 tonne/habitant/year (Hansen, 1992) and in 2002 it was
estimated 2.0-2.57 tonnes/habitant/year (Cochran and Townsend, 2010).
The generation of construction and demolition waste is influenced by
many different factors including the construction and demolition practices
adopted; the economic and market factors such as market size, availability
and cost of natural aggregates compared to the costs of delivery for recycled
aggregates; the regulatory framework that provides incentives to minimize
waste generation in construction sites and disincentives for waste disposal
in landfills; perceptions regarding the quality of recycled materials and the
absence of use in codes of practice, specifications and quality assurance
mechanisms (Bakoss and ravindrarajah, 1999).
The composition of construction and demolition waste is also variable,
depending on geographic region, time of the year and type of work, among
other factors. When coming from construction, the composition is dependent
on the stage of the work, since the stage of concrete structure is a higher
incidence of fragments from concrete, steel, wooden forms, among others,
while in the finishing stage, predominance of residual mortar, bricks, tiles,
ceramics, among others (Poon et al., 2001). If construction reforms, there
