Page 137 - Materials Chemistry, Second Edition

6.4 Recycling of construction and demolition waste 133
for noncompliance with the required specifications, as well as marble deposits provided a
large quantity of aggregates of different sizes induced by fragmentation operations, sawing
of large stones; furthermore, processing plants proliferate a very large quantity of wastes
consisting mainly of powders and sludge (Belachia and Hebhoub, 2018). Most of the CDW
comes from the demolition process while minor portions (around 10%–30%) are generated
during the construction process (EPA, 2018; Ning, 2017). Reducing, reusing, and recycling
of CDW has become an urgent and essential issue, as inappropriate CDW treatment will
cause severe environmental issues and land use threats.
Countries around the world reduce CDW by introducing different legislation and raising
awareness. Japan, Singapore, and some European countries are at the forefront in the treat-
ment and reuse of construction waste. In Japan, there are more than 20 subdivisions of
“construction by-products,” which are scientifically processed according to categories. The
main principle of treating CDW in Japan is to reduce the generation of waste on the construc-
tion site and reuse it as much as possible. Singapore focuses on setting standards for green
buildings to reduce the generation of construction waste from the source. According to the
European Union statistics office, the total amount of waste generated in the European Union
was over 2.5 billion tons, of which almost 860 million tons belonged to construction and de-
molition activities (Bravo et al., 2015). Some European countries have achieved the goal of
70% CDW recycling. Statistics show that the total mass flow of recovered waste accounts
for more than 80% of the total waste generation in member states such as the Netherlands,
Germany, and Denmark (Eurostat, 2017).
Current CDW processing and recycling techniques can be considered to be common across
Europe. A common CDW recycling plant usually consists of:
(1) reception, weighing, and visual inspection;
(2) manual preselection (for unsegregated streams), rejection, and diversion to alternative
treatments;
(3) screening of large materials;
(4) magnetic separation;
(5) manual separation of plastic, wood, and other waste streams, if required;
(6) crushing; and
(7) screening and secondary crushing, which is applied depending on the goal product mix
(Ga ´lvez-Martos et al., 2018).
However, in some regions there is a significant amount of illegal dumping and a hetero-
geneous market for secondary materials, which hinders the development of the secondary
materials market.
In order to achieve zero landfill for CDW in the United Kingdom, the construction industry
in the United Kingdom usually begins to estimate the total life cycle of waste production at the
design stage and gives a plan for recycling construction waste. The United Kingdom enacted
specific construction waste management regulations to record the production and type of
construction waste on the construction site in order to achieve the purpose of recycling con-
struction and demolition waste. The UK Government sponsored the Waste Resources Action
Program, which led to a variety of work undertaken to increase recycling for CDW. This
included working with the construction sector to specify higher levels of recycled content,
a major program of assisting companies to reduce CDW to landfill and assisting in financing