Why Reuse And Recycle

The construction and building industries consume huge quantities of materials (see Table 1.1). The environmental impact of the extraction, gathering and production of these materials is large and growing. Moreover, when buildings are constructed large quantities of materials are wasted and most of these are sent to landfill (see Table 1.2).

Table 1.1

Quantities of materials used in building and construction In UK (CIRA SP116, Voi.A, 1995)

Table 1.1

Material type

Annual consumption

Minerals (crushed rock and gravel)

254 million tonnes

Metals (steel, copper, brass, aluminium and alloys)

3.35 million tonnes

Timber products

3.85 million cubic metres

Polymers (PVC, polyurethane, polystyrene, polyethylene)

c. 0.5 million tonnes

Paints

c. 0.4 million tonnes

Table 1.2 Estimate of annual quantities of waste generated by construction processes in UK [McGrath et al, 2000]

Material type

Annual quantity

(million tonnes)

Concrete, bricks, blocks, aggregate

3.5

All metals

2.8

Excess mortar/concrete

1.2

Plastic packaging and plastic products

0.9

Timber and timber products

0.8

Plasterboard and plaster

0.3

Paper and cardboard

0.2

Vegetation

0.1

Other

0.2

Total

When buildings are partially or wholly demolished the materials of which they were constructed are released and, unless uses are found for them, they have to be sent to landfill as "waste". Accurate figures for the quantities of materials produced from building demolition are not available as they are usually included within total figures for all construction waste. Estimates vary from 15 m tonnes to 30 m tonnes within a total of about 70 m tonnes of construction waste per annum in the UK (see Table 1.3).

CD U

Table 1.3

Estimate of annual quantities of materials arising from demolition In UK [McGrath, et al, 2000]

Table 1.3

Material type

Annual quantity

(million tonnes)

Concrete

12.0

Masonry

7.2

Paper, plastic, cardboard and other

5.1

Asphalt

4.5

Wood-based

1.0

Other

0.2

Total

While data may be imprecise, it is widely agreed that, whatever the figures, we cannot continue indefinitely, as a society, to send such potentially-valuable materials to ever-diminishing landfill sites. It is unsustainable, unethical, uneconomic and environmentally damaging. Nor does it make long-term business sense - there are potentially large markets for reused components and recycled materials.

In Holland, for example, some 15 million tonnes of demolition and construction waste are produced every year - a volume of material sufficient to make the foundation for a six-lane motorway 250 kilometres long. In Britain, the figures are many times larger. Such facts alone are a key driver for seeking the most economic, efficient and environmentally sound manner for dealing with the problem.

While Britain has sufficient landfill sites for the immediate future, most of the buildings being constructed today will be finally demolished between 30 and 70 years from now, by which time there will probably be a shortage of landfill sites, and the cost of disposal will be very high.

The largest quantities (by weight) of the materials liberated in building demolition are usually steel, concrete and brickwork. Virtually all the steel is already reused or recycled (see Table 1.4) and many demolition firms now find uses for much of the crushed or uncrushed hardcore that is produced in the demolition process (see Table 1.5 for the figures for one firm).

Table 1.4 Average end-of-life scenario data for steel in European Union (Durmisevic and Noort, 2002)

Product made of steel

Recycling %

Reuse %

Landfill %

Girder

88

11

1

Lintel

88

10

2

Doorframe

90

9

1

M&E services

87

11

2

Purlins & rails

87

11

2

Composite floor decking

81

15

4

Composite cladding sandwich panels

53

37

10

Profiled cladding and roofing sections

81

15

4

Heavy structural sections

87

11

Table 1.5

Annual tonnage of hardcore materials produced on site by one UK demolition firm (DSM Demolition)

Table 1.5

Material type

Annual quantities

Tonnes

%

Unprocessed hardcore left on site

11 000

5

Crushed hardcore left on site

40 000

18

Crushed hardcore sold off site

4400

2

Contaminated hardcore to landfill

400

0.2

Unprocessed hardcore moved off site awaiting crushing

166 400

74.8

Total

222 200

Current demolition practices are highly efficient at removing high-value items and rapidly reducing the remainder of a building to materials that can be segregated to facilitate subsequent handling (see Appendix A: The practice and management of demolition activities).

There is a thriving reclamation industry although it is largely restricted to what might be called the architectural salvage sector -the salvaging and reuse of components and materials from various periods of our building history (see Table 1.6).

Table 1.6

Selected reclaimed products and materials [McGrath, et al, 2000]

Table 1.6

Material type

Annual quantities - Tonnes

Architectural and ornamental antiques

141 000

Reclaimed timber beams and flooring

242 000

Clay bricks

457 000

Clat roof tiles

316 000

Clay and stone paving

694 000

Total

Despite these successes, much demolition material is sent to landfill so there are compelling reasons for trying to reduce these quantities by increasing the recycling of materials and, whenever possible, exploiting opportunities for reusing components from buildings before those "materials surplus to requirements" become simply "waste materials". Furthermore, shifting from recycling to reuse can reduce the re-processing involved and lead to energy savings. Achieving these goals would not only reduce the growing pressure on landfill sites, but also reduce the need to extract new raw materials from the earth. This will reduce the environmental impact of extraction processes and slow down and eventually halt the depletion of finite resources on our planet.

+1 0

Responses

  • Abbie
    Why reuse and recycle?
    8 years ago
  • katherine
    Why reuse not widely practiced?
    8 years ago
  • diann
    Why reuse timber products?
    8 years ago

Post a comment