Osmani, Price, Sutherland. Construction product manufacturers' waste targeting and prioritising

7/28/2019 Osmani, Price, Sutherland. Construction product manufacturers' waste targeting and prioritising

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Construction product manufacturers waste targeting and

prioritising

Mohamed Osmani, Andrew Price, Malcolm Sutherland

Department of Civil and Building Engineering

Loughborough University

Loughborough, Leicestershire LEU 3TU

Drafted in April 2007; revised May 2013

Abstract

The construction industry places a significant demand on the environment through

consumption of natural resources, emissions, and waste production. Each year the

construction industry in the UK generates approximately 109 million tonnes of waste,

comprising 60% from site-based activities and 40% from product manufacturing. Driven by

legislation, client demand and increased disposal costs, waste minimisation has become an

important consideration for the UK construction industry.

This paper emerged from a DTI-funded project, the aim of which is to assist constructionproduct manufacturers in the UK to make more efficient use of materials and processes. The

project investigates a number of construction waste materials across their whole life cycle

to examine the potential of their reuse and recycling. The aim of the paper is to discuss the

findings of the first stage of the project. Representatives of construction product

manufacturers and waste management consultants attended a workshop, where they

identified the key cross-sector waste streams; highlighted the main benefits and challenges

regarding current or potential recycling routes; and ranked the identified wastes in terms of

their recycling potential. The identified waste materials considered to have the greatest

recycling potential included: (i) damaged bricks/blocks; (ii) unsalable concrete units; (iii) GRP

(glass-reinforced plastic); (iv) sawdust from timber production, and (v) timber packaging.

Keywords

construction product manufacturers

waste materials

targeting

prioritising

re-use

recycling


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1: Introduction

The construction industry places a significant demand on the environment, through

consumption of natural resources; greenhouse gases emissions;, and the generation of

waste materials throughout the products' lifecycle, McEvoy et al (2004) reported that the

transportation of construction materials accounts for over three-quarters of mass flows in

general, and that in the UK, over 90% of non-energy-based mineral consumption is

attributed to construction. Additionally, the capacity of landfill space is rapidly diminishing

within the UK, and has been for several years (DETR, 2000). During the late 1990s, the

number of landfill sites declined by nearly one third (Osmani and Li, 2006).

Construction and demolition (C&D) waste disposal to landfill has been strongly discouraged

for many years due to its heavy and voluminous nature, and due to the high recycling

potential of several construction materials (Peng et al, 1997; Poon et al, 2004) European

attention was drawn to C&D waste in 1991, when the European Commission identified it as

one of the major waste streams under the Priority Waste Streams Programme (European

Commission, 2001); since then, recycling rates of C&D waste in the UK have increased,

particularly with "hardcore" materials such as concrete, which are a growing substitute for

primary aggregates (Soutsos et al, 2004). Nevertheless, not all construction materials are as

easily recyclable, and information regarding C&D waste recovery, especially of that arising

from construction product manufacture and distribution, is limited (BRE, 2006).

In view of these issues, a UK Government-funded project entitled 'BeAware' (Built

Environment Action on Waste Awareness and Resource Efficiency) was initiated in 2005.

The aim of the project is to assist construction product manufacturers in the UK to make

more efficient use of materials by investigating re-engineering processes such as productdesign, manufacture, installation, use and eventual disposal; and examining new methods

for reuse and recycle wastes emanating from products' manufacturing process.

This paper reports on the findings of the first stage of the 'BeAware' project, based on the

information produced by delegates representing cross sector construction product

manufacturers and waste management consultants who attended the First 'BeAware'

workshop. This contains a review of the following:

legislative and policy drivers in the UK, which promote their recovery and recycling;

current recycling practices and limiting factors in construction; and,

the results of the First 'BeAware' workshop activities:

o waste targeting (whereby delegates listed waste materials in their respectivesector arising throughout the construction products' lifecycle); and,

o waste prioritising (whereby delegates listed the recovery benefits andproblems of the identified wastes, and ranked them in terms of their

recycling potential).


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2: Construction recycling drivers

Raw material extraction and waste disposal to landfill have been highly charged issues for

both government and industry within the UK. The environmental benefits achieved through

diversion of wastes from landfill include, reduction in greenhouse gases (namely methane);

recovery of waste materials, and development of markets; reduced loss of amenity; and

reduced demand for raw materials (Collins, 2003). The UK construction sector alone

generates around 92 million tonnes of waste per annum, of which around 13 million tonnes

comprise unused new products which are then sent for disposal; the demolition sector in

England and Wales generates another 91 million tonnes of waste (DTI, 2006).

The main policy-based, legislative and financial drivers behind recycling waste streams in the

construction industry are listed in Table 1 over-page (relevant to 2007). Within the UK, a

range of agencies and initiatives have been created, in order to facilitate increased waste

minimisation and recycling, which is increasingly becoming mandatory under legislation

such as the landfill, hazardous waste and packaging waste directives. In addition, tax

measures to deter disposal of waste to landfill and to counter market competition from

primary materials, namely aggregates, were introduced within the past decade, and some of

the tax revenues are currently used to subsidise recycling programmes (Wilburn and

Goonan, 1998; Guthrie et al, 1999; Hawkins and Shaw, 2004; DEFRA, 2007).

The financial drivers are currently being strengthened, whereby landfill tax on active wastes

will be raised by 8/tonne each year until 2010/2011, and the aggregates levy will be raised

from 1.60/tonne to 1.80/tonne (HM & Customs, 2007). In addition, there is a strong

economic incentive for the UK construction industry to reduce or recycle waste materials; it

has been reported that up to 5% of the industry turnover is consumed by waste, with over200 million being spent on landfill tax alone (BRE, 2006b). Case studies of construction

sites within the UK have revealed that improved waste management led to savings of up to

20% of materials occurring onsite, and financial savings accounting for 3% of the build cost

(Envirowise, 2006).

There is limited information regarding precise quantities and volumes of construction waste

materials (BRE, 2006). The composition of C&D waste is generally dominated by clay bricks,

concrete and other "hardcore" products. Concrete and masonry has been estimated to

comprise as much as 80% of C&D waste (European Commission, 2000). Hardcore wastes

include concrete and ceramics, plaster and cement. Non-structural materials such aspackaging are also significant; packaging alone may account for between 15% and 20% of

total C&D waste arisings (DETR, 2000).

Waste materials from the construction industry are produced as a result of demolition, off-

cuts, or improper material handling and management; Guthrie et al(1999) reported that as

much as 20% of onsite ordered materials ended up as waste, often through poor storage or

handling methods- Nevertheless, literature failed to identify robust information regarding

the quantities of construction material wastes and their current recycling status within the

UK (Gregory et al, 2004). This is particularly the case regarding information on waste

generation during construction product manufacture, partly for reasons of commercialconfidentiality (Soutsos et al, 2004; Smith et al, 2006).


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Table 1: legislative and economic factors driving increased waste reprocessing in the construction industry

Legislation Details

Restrictions and Targets

The Hazardous Waste

Regulations 2005 (HWR)

- Wastes including CD&E (construction, demolition and excavation) wastes must beassessed as to whether or not they contain absolute hazardous materials, or mirror

hazardous materials (i.e. those containing dangerous substances)- Hazardous properties include corrosivity or toxicity

The Packaging and PackagingWaste Directive 94/62/EC

- Minimum 60% weight of all packaging waste to be recovered by 2009- Minimum 55% weight of all packaging waste to be recycled by 2009

Quality Protocol on Gypsum

from Waste Plasterboard

(Environment Agency)

- The 10% Rule governing waste plasterboard disposal to landfill (i.e. max. 10% of wasteto landfill comprising gypsum) will be abolished in 2009

- In future, no plasterboard shall be disposed of to landfill (in England and Wales)Site Waste Management Plans - Implementation mandatory for projects worth over 300,000 (300k)

- Contractors responsible for project worth up to 500k must forecast waste arising typesand quantities, and propose re-use, recycling and disposal actions

- Contractors responsible for projects over 500k must collate detailed waste data recordsand must specify if waste is being recycling onsite or offsite

- Contractors must ensure there is no illegal waste disposal activity (e.g. fly tipping)Waste Framework Directive

- Nearly all household, commercial and industrial waste is classified as Directive waste,and must be assessed as to whether or not it is Hazardous WasteTaxation

Aggregates Levy (UK) - This is a tax on sand, gravel and rock excavated inland or offshore in UK waters- Rate: 2/tonne (2009)

Climate Change Levy (UK) - Applies to electricity, natural gas supplied by gas utility, petroleum and liquid gas, coal,lignite, coke or coke derivative fuel used by businesses

- Rates range from 0.456 to 1.242 pence per kWh or kg, depending on type of fuelFuel duty (UK) - Approximately 53 pence/litre for standard unleaded petrol, rising to 0.55/litre in 2009

- Approximately 57 pence/litre for standard diesel, rising to 0.60 in 2009Waste Strategy for England

2007; 2007 Budget

- Landfill tax to increase by 8/tonne per annum for standard waste until 2010/11- Tax rate for inactive waste: 2.50/tonne

- Tax rate for standard waste: 32/tonne (2008)Incentives

WRAP grants Some construction companies producing aggregates have received capital grants from WRAP,which in turn are invested in recycling testing and processing equipment

3: Current construction and demolition recycling practices

There has been widespread research into possible applications for construction waste

material recycling. Gregory et al (2004) noted that in 1991, approximately 63% of C&D

waste was recycled The authors also reported on a survey conducted under the DETR in

1998, which revealed that less than 10% of waste generated during construction stage wasbeing recovered in the UK. Construction, demolition and excavation waste destinations in

England include (ODPM, 2004):

approximately half (45 million tonnes) being recycled for use as secondary

aggregate;

approximately 7% (6 million tonnes) being used for landfill restoration/engineering;

approximately 15% (13 million tonnes) being used for quarry void backfill; and,

the rest being deposited to iandfiil and registered exempt sites.


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Similarly, BRE (2006) reported a very high recovery of waste materials arising during

demolition, whereby approximately 80% is recycled, 13% re-used, and 7% is sent to landfill

,of which 32% was quoted to comprise hazardous wastes). Crushing of bricks, blocks and

concrete produce low-grade bulk fill for nearby sites (e.g. road construction) is widely

practised, particularly since these dense materials are predominant in structures, and are

costly to transport and dispose of to landfill or to recycling outlets (Gregory et al, 2004). On

the other hand, metals are easily reprocessed and are often entirely recycled, or in some

instances re-used (Guthrie et al, 1999; McDonald and Smithers, 1998; Addis et al, 2004);

while excavated soil and sub-soil is also mostly recovered, and re-used predominantly for

landscaping (Guthrie et al, 1999). Comparatively lower proportions of plastics, drywall,

timber, insulation and glass materials are recycled and/or re-used (Peng et al, 1997;

McDonald and Smithers, 1998; DETR, 2000; Addis et al, 2004; Market Transformation

Programme, 2006).

4: Recycling technical and economic limiting factors

Recovery and reprocessing of waste materials is not always practical or financially viable,

and several factors need to be taken into account (Peng et al, 1997; Guthrie et al, 1999;

European Commission, 2000; Tarn and Tarn, 2006b):

the recycled materials market being in competition with the primary materials

market;

the costs of segregating, storing, transporting and reprocessing;

the abundance of the waste material within a region and a specified period of time;

site area and storage space available for recovering materials;

the physical and chemical integrity of the recovered materials; and,

potential hazards associated with particular waste materials.

Recycling or re-use of waste materials will generally be more economically competitive in

areas distant from landfill and raw material suppliers such as aggregate from quarries (Tarn

and Tarn, 2006b), and where environmental legislation imposes strong financial

disincentives on the use of primary resources and on landfilling (European Commission,

2000; Duran et al, 2006). A prime factor which may inhibit recycling is the cost of

transporting materials from source to receptor, whereby the economic return on recycling is

said to be negligible when the material is transported across a distance exceeding 25 km

(European Commission, 2000). This is further complicated by the sporadic occurrence of

varying quantities and types of waste, which add to the expense of collecting and

transporting waste materials from source to receptor (i.e. recycling depot) (Guthrie et al,

1999).

There is a need to add an introductory statement from literature to justify (i.e. the major

construction waste streams) and introduce the waste streams that are discussed below.


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4.1: Bricks/blocks and concrete waste

C&D waste is dominated by inert mineral waste (namely bricks, blocks and concrete,

comprising almost 80% of C&D waste), which dwarf other waste streams including plastics,

metals and timber (European Commission, 2000; BRE, 2006). Although their relative

abundance strongly justifies their recycling, hardcore materials (particularly from

demolition) are generally used in "low-grade" applications (BRE, 2006). The re-use of

"vintage" clay bricks from demolition is a more valuable market, although the removal of

mortar must be conducted manually, hence at longer time and cost (Gregory et al, 2004;

Tarn and Tarn, 2006). There is also a very limited market for using crushed hardcore

material as aggregate in new concrete, mainly due to distrust over the perceived lower

quality of recycled aggregate (e.g. contamination by plastics, wood, etc.) (Soutsos et al,

2004). Although widely practised, the recovery of bricks and blocks Is a demanding process;

Gregory et al(2004) mentioned that the crushing of bricks into aggregate requires energy-

intensive, heavy machinery, which are expensive to operate and take up space.

Plastic waste materials

Plastics waste streams are heterogeneous, requiring thorough separation at source.

Among these materials, PVC is said to be the predominant construction products' waste,

accounting for as much as two thirds of plastic waste arisings (European Commission, 2000).

In spite of this, PVC is among the least recoverable construction wastes, owing to their

lightweight properties, which in turn make transportation prohibitively expensive

(Leadbitter, 2002). The potential returns on recycling of plastics are also restricted by the

complicated range of polymers occurring in the waste stream, as well as limited recycling

outlets (Leadbitter, 2002; Collins, 2003; Addis and Schouten, 2004). Plastic wastes may alsobe contaminated with soil and metal components, requiring washing procedures prior to

reprocessing (Rebeiz and Kraft, 1995; Leadbitter, 2002).

Wood and Timber waste materials

The recovery of timber materials, including packaging, is dependent on the physical

integrity, as well as the presence of contaminants. Waste generated alongside timber

product manufacture is minor compared with waste generated alongside joinery and during

construction, and the markets for recycling residues from timber manufacture (including

pallets and sawdust) is firmly established (TRADA, 2005). Physical components and design oftimber products are important issues; timber pallets, planks and panels which are

undamaged may be re-used, although cleaning and denailing may be necessary (Tam and

Tarn, 2006). Damaged timber materials may be converted into use for soil conditioning

(e.g. mulch), or chipped for use in new timber products (e.g. chipboard, furniture) (Magin,

2001). Treated wood streams, including painted and preservative-treated wood are

generally less suitable for recycling (Peng et al, 1997; Kartam et al, 2004). Overall, the

scope for recycling timber materials from C&D waste is limited due to a number of

constraints, including a lack of recycling outlets, limited space on-site for segregation, and

the presence of contaminants in treated wood (Magin, 2001).


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Other construction products' waste streams

Metals can easily be segregated, re-melted and recovered, and there is a highly developed

market for recycled metals in many countries worldwide (Tarn and Tarn, 2006). Hence most

recovered metal, including that from construction and demolition, is currently recovered;

even lower-value metals such as steel are very rarely sent to landfill (Addis and Schouten,

2004).

Another waste stream which is often diverted to landfill is plasterboard, particularly that

arising from demolition (partly due to being contamination by soil or other wastes).

Nevertheless, this is currently being redressed by industry and government; "take-back"

schemes for off-cuts arising during construction are being operated by manufacturers,

alongside the recent imposition of the "10% Rule", which restricts the hazardous content

permitted within landfill, due to the sulphate content of plaster, and the potential for

groundwater contamination)(Market Transformation Programme, 2006).

3: Methodology

This paper details and reflects on the findings of the First BeAware Workshop, entitled

Waste Targeting and Prioritisation (held in May 2006). Workshops are a valuable

opportunity to network with experts and stakeholders, who simultaneously provide

contemporary information based on industry experience (Park and Martin, 2007).

The aims of the workshop were threefold; identify cross-sector waste streams (waste

targeting); investigate the benefits and challenges associated with their re-use andrecycling; and rank the identified wastes in terms of their recycling potential (waste

prioritising). From the literature review, four major construction industry sectors were

identified: bricks and blocks, cement and concrete, plastics, and wood and timber. The

workshop was attended by 37 delegates representing a range of construction product

manufacturers, demolition contractors and waste management consultants. The delegates

were grouped into five functional clusters, in order to provide a focus on each industry

sector. These were:

Plastics manufacturers,

Wood and timber manufacturers,Brick/block manufacturers,

Cement/concrete manufacturers,

"Catch-all" manufacturers (companies producing different products from above

categories (e.g. gypsum), or a wider range of products); and,

Waste management consultants.

The workshop facilitated activities were threefold. During Activity A (Waste Targeting),

delegates were asked to identify types of generated wastes in their respective industry

sector, and locate their occurrence within the construction product lifecycle (production,

distribution, point-of-use, end-of-life). During Activity B (Waste Prioritisation), delegateswere asked to list drivers and barriers associated with re-using or recycling the identified


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waste materials, and ranking them in terms of their recycling potential. During the Plenary

session, each delegate cluster presented their findings, and general debate was held on

some of the issues raised in relation to re-use or recycling.

4: Results

4.1: Waste Targeting (Table 2)

During the first facilitated workshop activity, the delegates listed all the waste materials

arising in their sectors, and indicated where these occurred within the construction product

lifecycle (production, distribution, point-of-use, end-of-life). Certain waste materials are

exclusively connected with product manufacture, such as off-cuts (e.g. PVC, timber) as well

as air pollution control device dusts (e.g. air filter fines, cement kiln dust, factory wastes

such as discarded containers and hydraulic oils).

Packaging wastes tended to be one of the few waste materials which arise during

construction product distribution, alongside over-ordered or damaged/unsalable products

such as bricks or concrete units. Packaging wastes (including plastics, wood (e.g. pallets) and

cardboard) also arise during point-of-use (construction), alongside product off-cuts,

rejected/damaged products, as well as excavated soil. Identified wastes from demolition

generally included discarded construction products, as well as other materials such as

electrical components or wiring.

Results of the waste targeting exercise are addressed individually for each delegate cluster

throughout the remainder of this section.

Plastic manufacturers' waste streams

Delegates from the plastics cluster identified a wide variety of waste polymers, including

PVC and HDPE (high-density polyethylene). These wastes occur as off-cuts and as discarded

packaging, particularly at the point-of-use. Plastic product deliveries are accompanied by

non-plastic packaging, including timber pallets and cardboard. Plastic products such as

window profile, piping, and also membrane and insulation materials occur during

construction and demolition. During the plenary session, it was noted that 85% of profile

off-cuts generated during manufacture are currently recycled.

Wood and timber manufacturers' waste streams

A wide variety of by-products are produced during timber product manufacture, including

WESP (wet electrostatic precipitator) sludge, boiler ash, saw-dust, timber and solid timber

off-cuts, as well as excess paint alongside its application. Wood pane] off-cuts also occur

during distribution and at point-of-use, and non-timber wastes including plastics (such as

wrapping), glass and cardboard occur at construction sites. The three identified timber

products arising during demolition include untreated wood, treated wood and panels.


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Table 2: waste materials identified in the Waste Targeting exercise

Cluster Production Distribution Point of use End of life

Plastics

HDPE, PVC, Profile offcuts,

GRP, PET

Packaging, cardboard GRP, Damaged windows,

HDPE, polyethylene offcuts,

PVC offcuts, pipes,

polystyrene, packaging,

wooden pallets

Rigid insulation foam,

polymer, bituminous

roofing, sngle poly roofing,

PVC, GRP, PVC pipes, HDPE,

rainwater goods, rigid

insulation poly, vinyl foam,

resin cones for damp-proof

membranes, paper,

windows and window-

profile PVC

Woodand

Timber

Treated wood (in raw

material), plastics, process

by-product/off-cuts

(timber, treated wood),

WESP sludge, paint

overspray, boiler ash,

sawdust

Containers (paint tins),

wood bearers, plastic

strapping and wrapping

Paint and preservative-

treated off-cuts, glass,

cardboard, wood dust,

containers (paint)

Untreated solid wood,

panel board products,

treated wood

Bricksandblocks

Shrink-wraps, extractedmetals, cement, scrap units,

end-of-mix concrete,

spoiled fired bricks and

refractories, used

scrubbers, kiln dust,

packaging, polystyrene,

timber, used ceramic, fibre,

waste hydraulic oil

Cement, packaging waste(paper sacks, plastic

wrapping, pallets)

Waste packaging (paper,plastic), wood (pallets),

plastics, demolition

materials, fired brick

Demolition hardcore,extract rebar

Cementand

concrete

Unsaleable products,

bypass dust, factory waste,

packaging waste

Unsaleable products Packaging waste, expired

cement

Catch-all

Plasterboard, aluminium,MDF, overburden and

interburden, out-of-

specification mineral

powders, waste concrete

mix, scrap tiles

Batching plant waste, airfilter fines

Tile and slate off-cuts,packaging, insulation (over-

ordered or site off-cuts)

Plasterboard, glass,aluminium, steel,

insulation, fibre cement

slates, concrete/clay tiles,

demolished hardcore

Consultants

(GroupA)

Quarry waste, flooring,

ceramics, PVC

(manufacture waste, by-

products, emissions)

Ceramic and wood flooring,

pallets, packaging, over-

ordered products in general

Subsoil excavation and

spoil, gypsum board off-

cuts, packaging, over-

ordered products in general

Windows (metals, plastics,

glass), flooring, mixed

plastics, wood,

plasterboard, treated

timber, inerts (bricks,

blocks, concrete)

Consultants

(GroupB)

Off-cuts, damaged goods,

packaging, raw materials

Packaging Plastic containers, stow

render, paint pots, plaster

additive, insulation,

plasterboard, packaging,timber, damaged products,

plastics, glass, composites,

geotextiles, membrane,

cable and wiring, office and

general site waste (e.g.

hard hats, food,

newspaper)

Composite materials,

timber, flooring, plastic,

treated timber, hazardous

wastes, plasterboard,damaged products,

products comprising more

than one material, mix

aggregate (demolition

waste plasterboard,

contaminated bricks),

electrical equipment

(WEEE)

Bricks and blocks manufacturers' waste streams

Several waste materials and substances are generated alongside brick and block

manufacture, including scrubber/exhaust dusts, timber, hydraulic oils and plastic packaging.


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Damaged, contaminated or spoiled bricks and blocks also occur as waste at this stage, and

during construction. Packaging waste is prominent during distribution and point-of-use,

including timber and plastic materials. It is interesting to note that no bricks or blocks

wastage is indicated during these stages, although these products will inevitably arise as

waste during demolition.

Cement and Concrete manufacturers' waste streams

The most recurring cement and concrete waste materials listed include unsalable products,

packaging and factory wastes. Cement kiln dust was noted to occur within the

manufacturing stage, whilst expired cement is produced during demolition.

Catch-all construction products manufacturers' perspectives

The wastes identified include materials not listed by the previous four clusters, included:glass, plastering, metals (namely aluminium and steel), insulation, and ceramic products

such as tiles. Packaging materials were deemed less prominent, featuring only at point-of-

use. Plasterboard, metals, glass, and concrete wastes arise during manufacture and end-of-

use. Mineral powders and over/inter-burden wastes arise during the manufacturing stage.

Fibre cement slates and concrete tiles are also reported to arise during demolition.

Waste management consultants perspectives

Waste management consultants identified a widely varied and detailed range of waste

materials, especially occurring during point-of-use. In addition to waste materialsattributable to the construction products and their packaging, the consultants also

identified excavated soil and similar spoil arising during construction, electrical and

electronic waste arising from demolition (cabling, wiring), as well as non-structure-based

wastes such as those from site offices (e.g. paperwork) and labourers (e.g. safety clothing).

Packaging features prominently, occurring alongside distribution, point-of-use and

demolition.

5.2: Waste Prioritising (Tables 3a and 3b)

During the second workshop facilitated activity, delegates in each cluster listed some of the

key benefits and problems associated with recycling of the waste materials identified in the

first activity, and then ranked them in terms of their recycling potential.

Recycling potential of plastic manufacturing wastes

The plastics manufacturing industry delegates identified GRP (glass reinforced plastic) as the

most promising in terms of recycling potential due to its low salvaging costs, in spite of

ineffective segregation, limited facilities and absence of incentives to assist with its

recycling. These problems also blight the potential recycling of PVC waste; however, thismaterial was ranked second, due to the low collection costs, ease of reprocessing and its


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Table 3a: recycling potential, benefits and problems for ranked waste materials

(Plastics, Wood and Timber, Bricks and Blocks, Cement and Concrete sectors)


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Table 3b: recycling potential, benefits and problems for identified waste materials

(Catch-all and consultants clusters)


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relative abundance. Additionally, the benefits associated with PVC were equally associated

with PE (polyethylene), PU (polyurethane) and PES (polyether sulphone), nevertheless,

these benefits are offset by high collection costs or the difficulties in segregating specific

materials. Delegates also concurred that polyethylene recycling is at an embryonic stage.

EPDM (etnylene propylene diene monomer) and PET (polyethylene teraphthalate) carry

high market values; however, these are insignificant waste streams, hence their lower

ranking. Rubber was ascribed the lowest ranking due to the difficulty of its reprocessing.

Recycling potential of wood and timber manufacturing wastes

Sawdust, wood chippings and off-cuts were equally given a top ranking, owing to their

abundance, and their established recycling processes and markets. However, delegates

noted that these advantages are offset by widespread sources of these by-products,

requiring expensive transportation to recycling facilities. They noted that wood panel off-

cuts may also be difficult to sort, and enquired on the need to classify these as a "waste".

They also commented that increased recycling of metal and plastic packaging could lead to adepletion in their recydate market value. Conversely, treated timber was given the lowest

ranking, which was partly attributed to its poor mechanical qualities (e.g. damaged

components) and for containing hazardous chemicals, including CCA (copper creosote

arsenate).

Recycling potential of brick and block manufacturing wastes

Damaged products on construction sites were estimated to have the most promising

recycling potential, in addition to their waste minimisation scope through improved

handling, storage and controlled ordering. Bricks and blocks arising from demolition weregiven the second-highest ranking, due to their established reprocessing into secondary

aggregate, although the delegates noted that this crushing process generates noise and

produces dust. Scrubber (particulate dust) residues generated during brick manufacture

were ranked third, owing to their alkalinity (lime) and potentially hazardous content

(including hydrofluoric acid, chlorine and trace metals). Packaging and factory rejects were

ranked below scrubber wastes, due to their arising in smaller volumes, possibly at remote

locations.

Recycling potential of cement and concrete manufacturing wastes

Unsalable products (especially) concrete were given the highest ranking, since they can be

easily reprocessed or even returned into the production process, although the re-insertion

of material into products may compromise product quality. The second and third-ranked

wastes included packaging and factory wastes, and delegates mentioned that these can

include substances such as packaging or hydraulic oils, which can be recovered and could

also be used as fuel substitute. The delegates also noted that these wastes (e.g. packaging

and reinforced steel) are often recycled, although increased recycling potential is inhibited

by waste collection contractors' fees, particularly for collection and transport. Expired

cement and bypass (cement kiln) dust were accorded the lowest rankings due to their

unsuitable material performance. The delegates noted that expired cement possess ashorter working life, whilst bypass dust was considered by delegates to be hazardous, who


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stated that it is currently sent to landfill.

Cross sector products' recycling potential: "Catch-all" manufacturers perspectives

Timber packaging (e.g. pallets) was accorded the highest ranking, owing to its abundance

and occurrence throughout the construction product lifecycle, its ease of being re-used or

being converted into chippings. The delegates noted that these benefits can be offset by

low volumes arising on-site, and the costs of retrieving the material; this is similar to the

findings from the wood/timber cluster concerning panel off-cuts. The "catch-all" delegates

also reported that timber packaging reuse potential is limited by the dimensions and design

of the original product, which may not be of use to potential clients.

Delegates accorded the second-highest ranking to glass, noting that glass items may be re-

usable as well as recyclable. Likewise with timber packaging, the delegates also noted that

these benefits are offset by the costs of retrieving glass materials, which arise sporadicallyover a wide regional area. Delegates noted that potentially high transportation distances

and costs also limit the recycling potential of stone washing fines, although these occur in

abundance. It was also revealed that variable quality of stone washing fines (including

moisture/water content), and their sporadic occurrence further restricts their recycling

potential. The delegates noted that waste insulation and plasterboard materials may be

contaminated, and accord these with medium ratings. They stated that there is some scope

for recycling plastic packaging, plasterboard and MDF due to low reprocessing costs, by

noting that plasterboard and insulation can be easily recycled, whilst air filter fines and steel

possess (potentially) high market values. These materials were accorded low rankings, partly

since recycling facilities may either be limited (e.g. plasterboard), or may not exist (e.g.insulation, MDF).

Cross sector products' recycling potential: Waste management consultants' perspective

Waste management consultants identified packaging materials as being the most potentially

recyclable, mainly due to their abundance and regular occurrence along the construction

product lifecycle, and reported that these benefits are offset by the wide variety of

packaging materials and types, leading to difficulties in segregating packaging wastes, and

the need to compact the materials (e.g. bulking, baling). Concerns were also raised by

delegates on confusion over packaging regulations.

Subsoil was highly ranked by the waste management consultants, who commented that

inert/clean subsoil can be used onsite for land reclamation, composting, as well as being

screened to produce aggregates. However, they also noted that "brownfield" soil may be

contaminated, leading to confusion over regulation (e.g. licenses, monitoring/remediation

requirements) and public distrust; they also questioned on where to send the contaminated

residues from "brownfield" soil.

As mentioned, plasterboard was accorded with a medium ranking by the consultants, due to

the benefits of its ease of reprocessing, large volumes and potentially large market, beingoffset by the issue of the "10% rule" encouraging continued disposal to landfill (as well as


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the difficulties and expense of segregation and collection). The consultants also mentioned

further deterrents affecting plasterboard recycling, including low recyclate.

Waste Prioritising

The most commonly noted benefits and problems relate to reprocessing, collection and

transport costs, the existence of recyclate markets and the ease of recycling. This is

supported by Peng et al(1997), Guthrie et al(1999), the European Commission (2000), and

Tarn and Tarn (2006 2) who acknowledged that the technical feasibility of reprocessing, and

the quantities of waste available strongly determine the viability of recycling. Packaging

materials (timber and plastic), timber waste (including sawdust) and some plastics (including

PVC) were reported by delegates to occur in high volumes.

This reflects the findings of DETR,(2000),, whereby packaging waste arising during

construction can be significant., however, plastic waste streams are comparatively minor

within C&D wastes (European Commission, 2000; BRE, 2006).

Recycling drivers

The benefits of an established market and attractive recyclate market values were also

commonly identified. The importance of these factors were also widely reported in the

literature (Peng et al, 1997; Guthrie et al, 1999; Tarn and Tarn, 2006). Established markets

were not mentioned by the plastics cluster, which might reflect the opinion by Leadbitter

(2002) on the limited recycling of plastics in general. Moreover, the benefit of established

markets was noted for a wide variety of waste materials, including packaging, glass and

bricks/blocks. This reflects the observation that wasted bricks and blocks (especially from

demolition) are widely crushed and used as low-grade aggreqate. It may also reflect therequirement for recycling under the Packaging Waste Directive (Peng et al, 1997; Guthrie et

al, 1999; Collins, 2003; Soutsos et al, 2004; Gregory et al, 2004; BRE, 2006).

Recycling barriers

A wider range of problems limiting the recycling of waste materials were identified by

delegates. The most commonly identified barrier to recycling was the cost of collecting and

transporting waste materials. This was echoed by the findings Peng et al, 1997; European

Commission, 2000; Guthrie et al, 1999; Durant et al, 2006; and Tam and Tam, 2006.

The issue of segregating waste materials was the second-most commonly identified

recycling driver, which are of particular relevance to plastics and wood/timber wastes, and

which also reflects similar comments made by Magin (2001) on timber wastes, and

Leadbitter (2002) on plastic wastes.

Technical and environmental problems also featured prominently among the problems

identified by delegates. These include the risks of contamination within waste materials and

degraded quality of the materials salvaged - issues which were reported by all delegate

groups. The problems of contamination were reported for GRP, treated timber, panel off-

cuts, plasterboard and insulation, hardcore , and plastics in general. This reflects theliterature findings, including the problem of soil and/or "alien" particles becoming mixed


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within plasterboard from demolition (Market Transformation Programme, 2006), and in

plastics (which require washing during reprocessing) (Rebeiz and Kraft, 1995).

Attention was also drawn by delegates towards the issue of hazardous waste classification

concerning treated wood, cement kiln dust (or bypass dust), contaminated sub-soil, as well

as MDF (medium-density fibreboard). As mentioned, these materials are classed as "mirror"

wastes due to their containing hazardous chemicals, and cannot be readily recycled without

further investigation (Environment Agency, 2006). Delegates also noted the confusion over

current legislation addressing the management of wastes including GRP, PVC, packaging,

subsoil, treated timber, and plasterboard (mainly due to the "10%" Rule (Market

Transformation Programme, 2006)).

6: Conclusions

This paper discussed the findings of the First BeAware workshop, which was attended by 37

delegates, including waste consultants, and representatives from construction product

manufacturers. The delegates identified the waste materials occurring throughout the

construction product cycle, mentioned the recycling drivers and barriers (benefits and

problems), and ranked the waste materials in each sector in terms of their recycling

attributes. The findings from the workshop provide insights into the variety and composition

of cross-sector waste materials arising throughout the lifecycle of construction products, as

well as drivers and barriers associated with their potential for recycling and re-use. The

identified benefits and problems comprised a wide range of issues, including economic and

financial factors (e.g. processing costs, supply and demand), material performance-related

factors (e.g. quality, contamination), and also some environmental, health/safety andlegislative issues (e.g. the "10%" Rule addressing plasterboard disposal to landfill).

The most prominent drivers determining recycling potential included high waste stream

volumes, ease of sorting and reprocessing, and the assurance of an established recyclate

market. The main barriers impeding recycling included collection and transport costs;

difficulty of segregating waste materials (especially plastics); contamination in the waste

(plastics, timber, plasterboard); and small volumes of waste arisings. The top-ranked

materials according to their recycling potential included: glass-reinforced plastic (GRP);

sawdust and wood chippings (as well as off-cuts); damaged bricks and blocks; unsalable

concrete products; and packaging materials (namely timber).

Acknowledgments

The authors are indebted to all the delegates who contributed to the information collected

during the first BeAware workshop, and extend their thanks to the project partners who

promoted and facilitated the event.


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Osmani, Price, Sutherland. Construction product manufacturers' waste targeting and prioritising

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