Assessing materials for recycling

paola sassi

Dr Paola Sassi of Oxford Brookes University
looks at a way of assessing specified materials
for their recycling potential.

 

Introduction


Environmentally conscious architects and designers are faced with difficult choices when it comes to material specification. Difficult choices because of the lack of environmental information about materials. Recycling is regarded as an effective approach to environmentally benign specification, but very little information is available to guide the specifier. The study summarised in this article considers the potential for recycling in the building industry and the indexing system developed by this study has the aim of providing guidance for architects and designers wanting to design for recycling, recycle elements of buildings or use recycled materials.

 

Survey results

 

no SUMMARY OF MATERIALS STUDIED description of materials to be reused/ reclaimed/ reprocessed current recycling practice index for suitability
for
recycling 		ranking index of
benefits
from recycling 		ranking
1 clay brick wall with lime mortar, to be reclaimed and reused minimal 0.86 6 0.60 14
2 clay brick wall with cement mortar, reprocessed for hard-core minor 0.76 13 0.51 18
3 calcium silicate bricks cement mortar, reprocessed to hard-core major 0.76 12 0.51 18
4 dense blocks with plaster internally, reprocessed in aggregate minimal 0.71 16 0.50 19
5 aerated blocks with external render, reprocessed in aggregate minimal 0.79 11 0.50 19
6 aerated blocks with plasterboard, reprocessed in aggregate minimal 0.84 7 0.50 19
7 stone ashlar walling, stones to be reclaimed and reused minimal 0.71 16 0.56 16
8 stone cladding to external wall, to be reclaimed and reused minimal 0.88 4 0.56 16
9 stone ashlar walling, stones to be reprocessed as hard-core minor 0.77 12 0.51 18
10 steel welded structure, sections to be reprocessed major 0.67 19 0.63 11
11 steel bolted structure, sections to be reused major 0.66 20 0.76 4
12 timber structure, timber sections reused minor 0.76 13 0.66 9
13 timber structure, reprocessed to manufacture timber boards minimal 0.69 18 0.49 20
14 pre-cast concrete elements, to be reused minimal 0.80 10 0.60 14
15 concrete structure, to be reprocessed to form aggregate major 0.72 15 0.47 22
16 timber windows reused as a whole element minor 0.77 12 0.68 8
17 timber windows disassembled and reprocessed minimal 0.65 21 0.58 15
18 aluminium windows disassembled and reprocessed minimal 0.71 17 0.70 7
19 profiled metal cladding coated with plastisol reprocessed major 0.86 6 0.70 7
20 untreated timber boarding reprocessed to form board material minor 0.88 4 0.43 25
21 profiled PVC cladding to be reprocessed minimal 0.69 18 0.74 5
22 clay roof tiles reused major 0.90 3 0.53 17
23 fibre cement slating to be reprocessed to hard-core minor 0.88 4 0.45 24
24 natural slating to be reused major 0.90 3 0.53 17
25 lead sheet roofing removed and reprocessed major 0.82 9 0.61 13
26 aluminium sheet roofing removed and reprocessed major 0.92 1 0.65 10
27 copper sheet roofing removed and reprocessed major 0.91 2 0.58 15
28 zinc sheet roofing removed and reprocessed major 0.82 9 0.53 17
29 stainless steel sheet flashings removed and reprocessed major 0.91 2 0.66 9
30 tern coated steel sheet roofing removed and reprocessed major 0.82 9 0.65 10
31 epdm membrane roofing reused minimal 0.82 9 0.83 3
32 pvc membrane roofing reused minimal 0.69 18 0.73 6
33 asphalt roofing removed and reprocessed minimal 0.60 23 0.70 7
34 blockwork partitions, blocks reprocessed to form hard-core minor 0.76 13 0.47 22
35 plasterboard partitions dismantled and reused minimal 0.83 8 0.62 12
36 plasterboard partitions dismantled and reprocessed minimal 0.74 14 0.48 21
37 timber doors removed and reused minor 0.83 8 0.62 12
38 timber doors removed and reprocessed minimal 0.76 13 0.48 21
39 steel doors disassembled and reprocessed minor 0.87 5 0.70 7
40 ceramic floor finish reprocessed minimal 0.80 10 0.46 23
41 timber floor finish reused major 0.87 5 0.62 12
42 vinyl floor finishes reused minimal 0.88 4 0.93 1
43 foam glass reused minimal 0.91 2 0.53 17
44 expanded polystyrene reused minor 0.87 5 0.86 2
45 cellulose fibre reprocessed minimal 0.63 22 0.33 26

 

Conclusion


Is recycling technically feasible and environmentally desirable?
For most materials the answer is yes. Current recycling has proved in its limited extent technically successful and economically interesting. The environmental benefits are in some cases minimal and in some cases substantial, but generally undeniable. If all materials could fulfil the technical and economic requirements for recycling, they too would be recycled.

To extend the recycling practice it is paramount that in addition to the structuring of a recycled materials market, recycling itself is facilitated through new design approaches and building methods.

The new design approaches may include the use of natural, durable, non-composite, non-toxic materials and components, possibly prefabricated, in any case mechanically fixed. This would allow for reusing elements over again, until they are eventually reprocessed to produce new materials.


While the practice of recycling and designing for recycling is not widely spread, there are examples to build upon. In ten years time recycling in the building industry may become a standard procedure and designing for recycling the common approach to design.

 

 

References


• Salvo - Reclamation Theory - April/May 1995
• Deutsche Bauzeitschrift - Recyclinggerecht planen and bauen - Vol. 43 - Feb. 1995
• Deutsche Bauzeitung - Recycling am Bau - Nov. 1994
• The Green Building Digest - Issues 1 to 15 - ACTAC The Technical Aid Network - 1995-1997
• CIRIA - Environmental impact of Building and Construction Materials Vol. A-E - June 1995