Reuse And Recycling Recovery opportunities

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During the past decades reuse and recycling of demolition wastes has occurred on a rather informal level. Reuse and recycling has only been applied if certain materials were regarded as valuable or saleable by the contractors. Otherwise the waste has been disposed of in the cheapest way. Architectural salvage is a growing business whereby elements of demolition are recovered for reuse elsewhere through a network of wholesalers and retailers.

Demolition methods are slowly changing with the introduction of selective demolition techniques and procedures. These allow the opportunity of sorting out materials which may be recycled if it is economically viable and the required treatment facilities are available. Most raw materials used for building and civil works construction are potentially valuable and could be reused or recycled if structures were dismantled using the correct procedures. Figure 5.5 provides a breakdown, by weight, of the various material components within a single family masonry house. The diagram exemplifies just how high volumes/weights of recovered materials could be achieved using selective demolition methods.

Masonry Single Family House

219087 kg

Electrical Installations and Devices

8 kg

Sanitary Installations and Devices

82 leg

Heating and Ventilation System

210 kg

Doors and Windows

2474 kg

Joinery

400 leg

Roofing

6998 kg

Roof Frame

5131 kg

Plumbing Work

400 kg

Floor Covering

7995 kg

Ceiling Covering

5162 kg

Wail , Paneling

6276 kg

1

r

Ceilings

Walls

Stairs

Foundations

63090 kg

80132 kg

5322 kg

35407 kg

Figure 5.5 Dismantling - precedence graph for a single family masonry house (Nicolai et al (1993))

Table 5.1 summarises the recycling opportunities for the main materials used in building/civil work construction.

Table 5.1 Overall list of materials which may be recovered

Main material in construction

Material for recovery

Recovery method

Concrete

Rubble

Recycling

Masonry

Stone, blocks

Reuse, recycling

Bricks

Bricks

Reuse

Tiles/clay pipes

Tiles/clay pipes

Reuse

Asphalt

Rubble, Moulded Asphalt

Reuse, Recycling

Wood

Timber, boards, doors, windows

Reuse, recycling

Glass

Glass

Reuse, recycling

Paper and cardboard

Packaging

Recycling

Metal

Steel structures, Cast iron

Reuse, recycling

Plastic

PE-foils, PVC drain-pipes and rainwater-pipes

Recycling

Soil

Soil

Reuse

Oils

Oils

Recycling

Chemicals/paints/solvents

Chemicals/ paints/solvents

Recycling

Plaster/gypsum

Plaster board (good condition)

Reuse

Water/aqueous solutions

Water/aqueous solutions

Recycle with treatment

Use of recovered materials

Use of recovered materials

Assurance regarding the performance of the material in the form of documentation on the product characteristics or references to its successful use is a major condition for recycling. If customers do not have confidence in the recycled products based on secondary raw materials, recycling of demolition waste will be limited to certain materials and uses.

During the past decade an increasing amount of tests have been performed on recoverable materials in order to create the necessary documentation on the product quality. The results of these tests have convinced a growing number of potential users of the positive effects of applying such materials. Although recycling processing methods are similar in most countries and demonstrations and standard tests on recycled products have been conducted, some materials will still require further documentation with reference to local regulations. To stimulate a significant increase in reuse and recycling rates further development and harmonisation of testing programmes is needed.

Bricks and concrete make up the main proportion of demolition waste. Experience in Denmark illustrates many possibilities for reusing/recycling these demolition materials. Crushed concrete aggregates have been used in new concrete in a variety of applications including highways, water and wastewater treatment, harbour and airport schemes. Meanwhile, mixed crushed concrete and brick have been used as aggregate for concrete structures in residential and commercial buildings. Waste brick, concrete and asphalt have many unbound base course pavement applications. Crushed concrete/brick can also be used as fill material.

The 1985 report by the Institute of Demolition Engineers (IDE) discussed the attitudes of the following groups to the recycling of demolition debris:

Demolition contractors

  • recycling is both a viable and necessary part of the demolition process
  • reclamation or recycling must fit into the confines of a site and there must be sufficient material to make hire of a crusher economically viable
  • acceptance of realistic demolition schedules by clients and the removal of unnecessary time penalty clauses would greatly increase the quality and quantity of recycled or reclaimed material
  • on the whole, selective demolition techniques are likely to improve the safety of demolition operations but this is not always the case
  • many demolition contractors allow a credit against the cost of a job for recovered material. In the normal situation where competitive tenders are invited, this reduction in cost is immediately passed on to the client
  • small contractors in urban areas favour local authority central recycling depots. This reduces transport and tipping costs and provides local construction projects with a source of aggregate and other materials. However, it is not in the interests of local authorities to provide such facilities
  • the level of co-operation exercised by local authorities very much influences the attitudes of demolition contractors.

Central and local government

  • the IDE feels that the attitude of government to recycling is not clear. It is therefore important for interested parties to take on a lobbying role
  • present central government is unlikely to interfere in the activities of commercial industry
  • demolition contractors would like some form of incentive for improving methods and increasing the quantity and quality of recycled aggregates e.g. capital grants towards the development of recycling plants, a redirection of purchasing policy to include recycled materials, and the development of national standards for recycled materials
  • local authorities have a remarkably variable opinion of recycled materials obtained from reprocessed demolition waste
  • London and the South East can boast the greatest awareness and support for recycling, in association with other urban areas
  • a few local authorities accept recycled demolition debris and encourage its use in their projects
  • several county councils are involved in using recycled asphalt for the repair and maintenance of roads.

Architects and Consultants

  • waste equals profit loss
  • in an economic sense, if you waste less you can save more
  • existing standards have been based on natural aggregate performance - new standards for recycled materials need to be produced or current standards and specifications amended to include recycled materials
  • lack of well documented laboratory tests and field trials means that designers often will not specify recycled materials as they are uncertain of their performance
  • refurbishment and restoration work often involves specifying genuine old timber beams, reclaimed bricks and tiles and thus the materials demand a premium price
  • some designers prefer homogeneity
  • putting the environment first is an altruistic act
  • altruism can promote public relations, advertising the caring company which in turn can increase market share, especially amongst 'green consumers'
  • the recycling/reuse of demolition waste is a growth market area with considerable business potential.

The 1985 paper was updated in 1992 by the IDE and EDA surveys. However, even the 1992 surveys' comments on attitudes and current practice with respect to recycling and reuse of demolition debris may no longer represent or even reflect the present situation. Such a study needs to be repeated.

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