Civil Engineering Reference
In-Depth Information
Hendriks and Janssen (2001) discussed several ways to reuse the various
constituents of the CDW, some of which are listed below:
∑ Concrete debris reused without any improvement in road construction or
as fill material for low-lying areas, among other applications. After the
concrete waste has been crushed and the aggregates separated into various
sizes, the waste can be used as aggregate for asphalt concrete production,
sub-bases for roads and concrete with recycled aggregates.
∑ Wood, when the undamaged part can be reused in the construction
itself and the non-reusable can be reduced to small sizes, in order to
be processed, making paper and cardboard. Alternatively, wood can be
burned as energy to be used, or decomposed by pyrolysis or gasification,
which can be used in the chemical industry after hydrolysis.
∑ The waste of asphalt can be reused in road construction, both for the
processing of new asphalt and the manufacturing of sub-bases, such as
granular material.
∑ Metals can be reused to produce new metal.
∑ Glasses, which would not be allowed to be processed and recycled
aggregates, are part of a function of alkali-silica reaction, although
there are studies that indicate its use as microphylous in the production
of concrete. These can also be recycled into new glass, fiber glass, tiles
and paving blocks or as additive in the manufacture of asphalt.
∑ Masonry waste, including brick, stone and ceramics, can be used in the
production of concrete, although there is a reduction in compressive
strength and special concretes, such as lightweight concrete with high
thermal insulation. The aforesaid can be used as aggregate in the
manufacture of bricks, even with the use of his fine piece, as filling
material, which can be burned and turned into ashes with the reuse in
their own construction.
∑ Paper and cardboard, as well separated and collected, can be recycled,
generally as a packaging material.
∑ Waste plastic from polystyrene (PS), polypropylene (PP), polyethylene
(PE) and polyvinyl chloride (PVC) can be recycled, although other resins
are difficult to be reprocessed.
∑ Hazardous waste must be incinerated or grounded with specific procedures.
Some waste such as oil, paints and solvents, abrasives and batteries, can
be recycled.
In order to ensure that recycled materials are permanently incorporated
into the market as raw material to be used in construction, it is necessary
to convince designers and builders, as well as the final consumer, that their
use has some competitive advantage and low technical and environmental
risks. This is necessary to overcome the prejudice against the use of material
which is considered to be a second rate, and rather to explore the ecological
side of recycling.
