Problem Definition, Aim and Objective
Construction and demolition waste (C&D) is deemed to be one of the largest waste streams within the EU and many other developed countries including the UK. The building industry in Britain is seen as a major extractor of raw materials.Out of the 30 million tonnes of the demolition waste every year in the UK, 12 million tonnes is only concrete waste; 7.5 million tonnes is masonry and 4.5 million tonnes of Asphalt.Out off this waste there is potentially valuable/useful material which is put to secondary use and a major amount ends up as low value material and used as bulk fill and also disposed off as landfill. This practice is considered nonsustainable for its environmental and economic implications.
It is believed that there could be benefits from the demolition process though utilizing the liberated materials in the building stages whether as reused or recycled materials. This is achieved by careful selective dismantling or removal of materials prior to or instead of conventional demolition (Deconstruction). It became apparent that reliable data and estimations on the quantities of demolition material, each individual material type, is the initial step toward qualitatively managing the problem of demolition waste.
The Research Question
The research is looking at the potential for improved resource efficiency on building construction projects. This is approached by identifying the different types and quantities of materials arise from the demolished site that could be recycled or reused for the new developed site or other sites (Stage 1, 2 and 3). In addition to that, the research investigates the possibility of the utilization of secondary materials from other sites and sources for the new development (stage 4).The attitudes of the client/owner, the design team and other key players, the forms of contracts used and the program constrains, are all to be investigated through an interview with the client (stage 5).This research is undertaken in relation to a case study of the Ashwell site in Cambridge which consists of 18 building that vary between warehouses, laboratories and offices.
Findings
A- Results obtained in stages 1 &2 (materials and their estimations and possible destiny) are:
Concrete
Brickwork
Metal
Cladding
Asphalt
Steel
Glass
Wood
Aluminium
Plastic
Asbestos
Tiles
&
Slates Water
Proofing
Totalm3
(16772.2 m3 )
9349.1
2776.4
1294.6
2346.2
641.0
124.8
70.1
13.4
6.5
10
136
168
Utilization
Crushed (Recycled Aggregate) Reused or Crushed as Recycled Aggregates
Fit to be Reused on or offsite
Aggregate fill
Sub-base
Reuse Steel structure & smelting
RecycleOr aggregates
Reused
Recycled (smelting)
Recycled
Landfill
Reused or crushed
Recycled
B- Results obtained from stage 5:
1) Utilization of reused and recycled material is accepted to the point of cost effectiveness. 2) This practice will be confined to the use of clean concrete waste and brickwork (after in-site crushing) in applications such as base, sub-base for roads, foundations and a layer for temporary roads to support vehicles during construction. Other utilization of material will be in landscaping, paving and repair. 3) Storage is a major problem in the site.4) Reclamation of high value brickwork is considered. 5) No use of reclaimed brickwork, tiles and other building components for the structural elements of the new site. 6) Reuse of the piles and foundation of the new Silo for building two wings attached to the old mill which is to be refurbished. 7) Timber reclaimed from old silo will be reused (after testing) in ceiling cladding, or wooden floors in the new development. 8) The site is considered a conservation area by the county council and the project will affect the local community and tourism sector as it is locate in the station road. Demolition will occur in winter for easiness to deal with dust and cleanliness (saves money!). 9) Complicity to get planning permission takes between 13-20 weeks leads to tight program for developer. 10)Health and Safety tests are required pre-demolition (type 3 survey). 11)Demolition contractor time program is 20 weeks. 12) Demolition contract includes NO conditions on the quantity of material recovery and destiny (reuse or recycling). 13) ‘Labour costs kill projects’. 14) For the lack of exiting drawing and record archives of the buildings there are no accurate estimations about quantities of materials pre-demolition. 15) Most buildings in the new development will be concrete frame with the same cladding such as stone, contemporary brickwork and glass and with flat roofs.
C- Stage 4 (Utilization of reused and recycled materials from other sources):It is being investigated |
