Resources,Conrvation and Recycling 54 (2010) 377–389
Contents lists available at ScienceDirect
Resources,Conrvation and
Recycling
j o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /r e s c o n r e
c
Evaluation of the economic feasibility for the recycling of construction and demolition waste in China—The ca of Chongqing
W.Zhao a ,R.B.Leeftink b ,V.S.Rotter c ,∗
a
Institute of Construction Management and Real Estate,Chongqing University,Shabei Street 83,400045,Chongqing,PR China b
Decistor bv,Bilderdijkstraat 4,2013,EJ Haarlem,Netherlands c
Department of Waste Management,Institute of Environmental Engineering,TU Berlin,Sekr.Z 2,Stras des 17,Juni 135,10623,Berlin,Germany
omita r t i c l e i n f o Article history:
Received 15January 2009
Received in revid form 3September 2009Accepted 6September 2009Keywords:
Construction and demolition waste recycling
Economic feasibility Model China
a b s t r a c t
In the recycling chain of construction and demolition waste,it is impossible to guarantee a certain quality of recycled products and to recycle a large amount of materials in recycling centers without mechanical sorting facilities.This counts even more when the produced materials have a low economic value,as is the ca with crushed and cleaned debris,also called aggregates.In order to asss if recycling can be done effectively,a feasibility study of the recycling of construction and demolition (C&D)waste is necessary.In the paper,the economic feasibility of recycling facilities for C&D waste in China’s Chongqing city was assd.Investigations on the current situation of C&D waste recycling in Chongqing showed that there were a large quantity of waste and an enormous de
mand for recycled materials due to the busy ongoing construction activities,which generated a large market potential and also brought a challenge to the strengthening of the recycling ctor.However,a full cost calculation and an investment analysis showed that,under current market conditions,operating C&D waste recycling centers in Chongqing might face high investment risks.Thus,the regulations and economic instruments like tax that can support the economic feasibility of recycling are discusd,and the recommendations for the choice of instruments are provided.
© 2009 Elvier B.V. All rights rerved.
1.Introduction
Construction and demolition (C&D)waste is one of the largest waste flows in the world.In China,urban C&D waste has reached 30–40%of the total urban waste generation becau of the large-scale construction and demolition activities resulting from the accelerated urbanization and city rebuilding (Chui and Yang,2006).Typical emissions from landfilling C&D waste are chemicals leach-ing from wood,drywall and concrete, e.g.,chromated copper arnate (CCA)-treated wood containing a lot of hazardous sub-stances such as chromium and lead is contributing to toxic impact
on ground and surface water and soil (Symonds,1999).Further-more,hydrogen sulfide (H 2S)as a major odorous component from C&D landfills contributes to acidification (Reinhart et al.,2004).Additionally,non-recycled waste will result in the loss of construc-tion materials and the occupation of landfill space for final disposal.From a broad point of view,disposal of C&D waste is not only a simple environmental concern,but also has major influence on the conrvation of resources for the whole society,since it avoids exca-vation of raw materials and provides substitution for materials like
∗Corresponding author.Tel.:+4903031422619;fax:+4903031421720.E-mail @tu-berlin.de (V.S.Rotter).cement and plastics which requires a significant amount of raw material,energy and funding to produce.
In China,the recycling lacks a central,stable and flexible inter-mediate between waste generation and landfill like recycling centers to transform the waste into recycled condary construc-tion materials.Unorganid collection and subquent sorting out by waste pickers is an obstacle to plant operators of construction materials.One key concern of an operator in a recycling center is to assure the cure quantitative and qualitative supply of recyclable waste materials.
The objective of this paper is to evaluate the economic feasibility for the recycling of C&D waste.By further simplifying the structural model of a feasibility study of a complex project,the esntial steps in pre-feasibility study of C&D waste recycling are identified with reference to Kohler (1997).a.Estimated generation of C&D waste.b.Market analysis of Estimated costs of recycling facilities.
d.
Analysis of investments (including payback period,internal rate of return and breakeven point).
As a ca study,the steps were applied to the situation in Chongqing.The C&D waste generation was estimated,the waste
0921-3449/$–e front matter © 2009 Elvier B.V. All rights rerved.doi:10.sconrec.2009.09.003
378W.Zhao et al./Resources,Conrvation and Recycling54 (2010) 377–389
composition was qualified and the potential demand in the mar-ket of main recycled materials(aggregates,brick,wood and metal) was analyzed.The economic feasibility of different recyc
ling facil-ities was evaluated by cost estimation and investment analysis. Meanwhile,the estimated cost and revenue of a recycling center in Chongqing were compared with that in the Netherlands tofind out successful factors of recycling centers,since it had been proved by our interviews with managers that C&D recycling centers in the Netherlands could be profitable over the last25years of operation. Eventually,a t of recommendations were concluded for policy makers through addressing the related regulations and economic instruments like tax contributing to the success of such a recycling facility as well as recycling market strategy.
2.Background
2.1.Definition of C&D waste
In general,although there is no uniform definition of C&D in the world,the waste is mainly classified bad on the origin and the composition of C&D waste.
In the United States,construction and demolition waste is a waste material that is“produced in the process of construction,ren-ovation,or demolition of structures.Structures include buildings of all types(both residential and non-residential)as well as roads and bridges.Components of C&D debris typically include concrete, asphalt,wood,metals,gypsum wallboard,and roofing”(Franklin, 1998).
In China,a National Guideline,Regulations for Construc-tion Waste Management in Cities defines C&D waste as:“The soil,material and others are discarded and generated by any kinds of construction activities,including the development,reha-bilitation,refurbishment of construction projects”(Ministry of Communications of the P.R.China,2005).
The two definitions are both bad on construction activities. However,the former is more complete and clearer than the latter, since structure and waste composition are described in the former.
2.2.C&D waste composition and generation
Dolan et al.(1999)identified as factors influencing the amount of C&D waste produced:
•The extent of growth and overall economic development that drives the level of construction,renovation,and demolition.•Periodic special projects,such as urban renewal,road construc-tion and bridge repair,and unplanned events,such as natural disasters.
•Availability and cost of hauling and disposal options.•Local,State and Federal regulations concerning paration,reu, and recycling of C&D waste.
•Availability of recycling facilities and the extent of end-u mar-kets.
C&D waste contains broken concrete(foundations,slabs, columns,floors,etc.),bricks,mortar,wood,metal and roofing materials(windproof,waterproof and insulating materials)as well as packaging materials(paper,cardboard,plasticfilm and other materials as buffer like wood and foam plastics).C&D wastes are categorized in a variety of ways,and different composition and characteristics of waste are described bad on each category.There are three main factors that affect the characteristics of C&D waste (ICF,1995):•Structure ,residential,commercial,or industrial build-ing,road,bridge).
•Structure ,low-ri,high-ri).mark twain
•Activity being ,construction,renovation,repair, demolition).
The direct methods for the determination of waste genera-tion and its composition is really weighing,measuring,sorting of the totalflow of waste or bad on sampling and extrapolation (Brunner and Ernst,1986).Indirect analysis us primary statistics on consumption,trade or other economic indicators or a descrip-tion of the stocks in order to estimate the generation rate.This approach was applied by Hsiao et al.(2002).
2.3.Potential demand for recycled materials
The demand for recycled material is determined by quality and price.The following application for condary construction mate-rial can be identified.
2.3.1.Aggregates
Natural aggregates(NA),containing sand,gravel,crushed stone and quarried rock are ud to prepare the foundation material for construction purpos(Poon et al.,2006).In China,there are exist-ing national standards forfine aggregates(GB/T14684,National Standard of Sand Utilization,General Administration of Quality Supervision,Inspection and Quarantine of the P.R.China,2001a) and coar aggregates(GB/T14685,National Standard of Crushed Stone,General Administration of Quality Supervision,Inspection and Quarantine of the P.R.China,2001b).Nominal sizes of two kinds of aggregates ranging from less than2.36to37.5mm,comply with the grading of GB/T14684and GB/T14685,respectively.
Tam and Tam(2006)described the following application for recycled aggregates(RA)sourced from the C&D waste recycling facility:foundation material for road construction,hardcore for foundation works,ba/fill for drainage,aggregate for concrete manufacturing and general bulkfill.Recycled conc
rete aggregates (RCA)differ from natural aggregates,due to the fact that impurities like the cement-stone are still attached to the surface of the original natural aggregates even after the process of recycling.The highly porous cement-stone and other impurities contribute to a lower particle density and higher porosity,variation in the quality of the RCA and the higher water absorption(Paranavithana and Abbas, 2006).In China,RCA is simply shredded by a crusher and ud as an additive for producing concrete by mixing with cement and water. Considering the impact of RCA on quality of concrete bad on par-ticle density,porosity and absorption,Chen(2005),Poon and Chan (2007),Wu(2004),Zhang and Qi(2004)indicated that the substi-tute rate of NA is equal to or less than20%and RCA could only be applied in concrete equal to or less than C30(“C”is an abbreviation of concrete,30means the compressive strength on a concrete cube is30MPa)with reference to GB/T14684and GB/T14685.Accord-ing to GB50010(code for design of concrete structures,Ministry of Construction and Administration for Quality Supervision and Inspection and Quarantine of the P.R.China,2002),concrete equal to or more than C30could be applied in prestresd reinforced con-crete construction.Namely,applications of concrete equal to or less than C30are mainly limited to low-ri buildings and some pub-lic concrete structures such as park place.The application of RCA in Shanghai ecological building in China is mainly ud in foun-dations and walls(Li,2009).In order to be more conrvative,it is assumed that the RCA content is5%in concr
ete equal to or less than C30,same with the substitute rate of NA for reinforced con-crete work in Kuwait(Kartam et al.,2004).Report of China Cement Association showed that about78%of total concrete production is C30and less than C30concrete in China(Anhui Development
W.Zhao et al./Resources,Conrvation and Recycling54 (2010) 377–389379
Table1
The potential applications of recycled wood depend on their quality.
Approach Quality A wood a B wood b C wood c
U for erosion control and groundcover
juniorschool
Organic soil amendment(in agriculture)after composting
Chipboard production
Wood chips for animal bedding
Fertilizer amendment in composing
Energy recovery by means of incineration
=feasible.
a A-quality wood—clear wood.
b B-quality wood—slightly ,with paints,glues and coatings.
c C-quality wood—hazardous woo
d wast
e contaminated with heavy metals,fire retardants and wood prervatives.
and Reform Commission,2007).The composition of concrete with cement:water:aggregate is1.2:0.8:8and60%of countrywide out-put of cement is ud to make concrete(Shi and Xu,2006).
RA and RCA are better as road foundation/bament than vir-gin material,for the strength caud by residual non-hydrated cement and the wide particle size distribution.To meet the strength requirement of ba and foundation of roads,according to thefirst application of RAC in pavement in
Shanghai,a RCA content of50% was ud in order to be more conrvative(Xiao,Wang,Sun,&Li, 2005).Meanwhile,RA is only ud in II and below II class high-way(for II,III and IV class highway,design speeds are limited to below80,40and20km/h,respectively)with reference to JTG B01(National Standard of Road Grate,Ministry of Communications of the P.R.China,2003).In addition,blast furnacefly ash is only allowed up to a certain(low)percentage in aggregates to enforce the road foundation,becau of the high content of heavy metals. Coal slag is to a certain extend ud in Western Europe for the same in road foundation(Feuerborn,2005).
2.3.2.Brick
Prently,brick is the largest component of C&D waste due to the traditional building habits and old-line production technology. However,converting building fashion from traditional brick struc-ture to reinforced concrete or steel structure,results in a decrea of the brick demand.At the same time,a ban on using clay as a raw material of brick had been implemented from2003by China Coun-cil for the Promotion of International Trade,since excavation of clay damages agriculture land.The substitutable bricks supported by patented technologies on bricking and cavity block made from inert materials(concrete,brick,mortar)(State Intellectual Prop-erty Office of P.R.China),are gradually being applied in building industry.Broken bricks are mixed with adhesive and cement to produce blocks.Co
nsidering environmental protection and qual-ity of bricking from mixed C&D waste,it is assumed that bricking and cavity block are mainly ud for non-residential structures and non-buildings(enclosure,ground tile and greening).Using broken Table2
Unit operations for C&D waste treatment.
Technique Function
Manual paration Separate recoverable materials,disturbing
materials
Crushers Size reduction
Wind-sifting Separate light and heavy materials in solid waste
by means of density paration
Screening Make a size paration
Shaking-table Separate light from heavy materials in solid waste Magnetic paration Remove ferro
us metals from non-magnetic
materials
Eddy current paration Recovery of non-ferrous metals
Flotation U the buoyancy produced by the attached tiny
air bubbles to the disperd hydrophobic particles
and lift them to the surface of the chamber brick as substitute for raw material for brick production must be the third main recycling approach of crushed brick next to road foundation and constructionfill.
2.3.3.Wood
Although wood is not increasing in the waste stream,new technologies of recycling wood are being explored.For instance, Logistics Engineering College successfully developed“artificial wood bricks”(mixture of woodflour and cement)as pre-embedding device of electricity,water,gas supply(Lu,2006). Considering wood quality in terms of specific contaminants,there are veral potent
ial and normal applications for recycled wood in developed countries,such as tho listed in Table1(Kartam et al., 2004;Rijpkema,1999).
In China,clean and de-nailed timber and boards are efficiently recycled and reud by contractors to avoid disposal fee and extra purcha cost of construction materials(Chen,2005).Uncontam-inated wood is ud for chipboard production and furniture at prent.Moreover,Finite market like animal bedding is an obstacle to decrea further unit cost by enlarging output,according to the economy of scale.Waste wood can be ud to increa the calorific value of municipal solid waste(MSW)for the waste incineration, which has under the high proportion of organic waste in China a calorific value below the lf burning temperature resulting in the substitution of additional oil and coal for the combustion process. However,for painted and waterproof wood,the market potential is limited due to the limited number of waste incinerators with sufficientflue gas cleaning,in China(Ji,2003).
2.3.4.Metals
The market for recycled metals such as steel or aluminum is fast growing becau of their high economical value.Steel con-sumption of construction industry has incread from14.56Mt (1991)to78.1Mt(2001)in China(You,2005).Increasing prices of metals encourage contractors to par
ate as much as possible reinforcement bars from crushed concrete on construction sites. Furthermore,metal industry also purchas deformed reinforce-ment bars from individuals scavenging at dumpsites.
2.4.Technologies for recycling centers
At prent,recycling technologies of C&D waste mainly come from mining industry bad on mechanical paration.Common paration techniques are described in Table2(Xing and Charles, 2006).The technology ud at recycling plants is determined by the scale of investment,quality requirement for recycled materials, cost and revenue of recycled production.A recycling plant usually consists of crushers,screeners,magnetic parators,wind-sifting and manual paration as demonstrated in Fig.1.To attain higher quality of recycled production,recycling plant contains a cond paration or more by means of combination of the technologies shown in Table2.
super baby380W.Zhao et al./Resources,Conrvation and Recycling初一英语上册知识点
54 (2010) 377–389
Fig.1.Flowsheet of a C&D waste recycling plant in the Netherlands (Jong and Kuilman,2008).
书香伴我行2.5.Cost estimation and investment analysis of recycling facilities Dolan et al.(1999)and Duran et al.(2006)propod a structural model of economic feasibility of recycling facilities and correspond-ing assumptions.Results of economic feasibility analys for C&D waste recycling facilities in the Taiwan,USA,Hong Kong and India were quoted in some studies,but few details about the method-ology ud and data collected were prented (Huang et al.,2002;MACREDO,2006;Tam and Tam,2006;TIFAC,2006).Duran et al.(2006)and Nunes,Mahler,Valle,and Neves (2007)discusd eco-
nomic feasibility of future recycling facilities in Ireland and Brazil bad on different scenarios such as capacity.Symonds (1999)showed detailed calculations and assumptions ud to estimate the cost of C&D waste recycling center in the USA.Klang et al.(2003)although considered environmental and social aspects besides eco-nomic aspect to evaluate recycling feasibility in Sweden,data in economic aspect were not comprehensive.Additionally,there has been relatively little rearch about economic feasibility of C&D waste recycling in China.
Cost estimation models are mathematical algorithms or para-metric equations ud to estimate the costs of a product or project (Dean,1995).The results are typically necessary to obtain approval to proceed,and are factored into business plans,budgets,and other financial planning and tracking mechanisms.The total costs of a product or project are divided into fixed costs (including costs for maintenance,depreciation,insurance and financing)and variable costs (including costs for labour,energy,transportation,etc.).
The definition of investment analysis is that a study of the likely return from a propod investment with the objective of evaluating the amount an investor may pay for it,the investment’s suitabil-ity to that investor,or the feasibility of a propod real estate development.There are various methods of investment analysis,including “cash on cash return”,“payback period”(PP),“internal rate of return”(IR
R),and “net prent value”(NPV).Each method provides some measures of the estimated return on an invest-ment bad on various assumptions and investment horizons.For investors,there are two necessary preconditions of the investment:•Life time of main equipments exceeding PP (time required to recover an investment)of investment on disposal facilities.
•Estimated profit from IRR (the discount rate for which the total prent value of future cash flows equals the cost of the invest-ment)exceeding opportunity cost of capital investment with reference to interest of saving.
To achieve economic feasibility of recycling,unit recycling cost (Rc )and acceptable unit profit (P )must be covered by main rev-enue from the gate fee to recycling per ton (Gf )and the revenue of
recycled materials per ton (RCp ),as the following Eq.(1).Rc +P ≤Gf +RCp (1)
3.Methodology
For this study,the data collection is comprid of three activities.•The data about generation and composition of waste in Chongqing were collected from 66construction and demo-lition sites through questionnaires nt to contractors and visiting some of the municipalities and contractors and data fr
om the Chongqing Statistical Yearbook (Statistical Yearbook is a large annual statistical publication compiled by Chongqing Municipal Bureau of Statistics ,which covers comprehensive data on Chongqing’s social and economic development per year.).The data about potential demand for C&D waste came from various literatures with priority being given to recent literature con-taining extensive bibliographies and the Chongqing Statistical Yearbook.
•Data concerning the fixed costs,especially equipment costs and corresponding certifications of recycling facilities,were obtained from various literature references and interviews with managers in recycling centers in the Netherlands as reference,since there are no such C&D waste recycling centers in China at this moment and thus no reliable cost data available.
•Data of operating costs like unit labour cost were identified with reference to corresponding prices in 2003by Chongqing Price Information Center (an authorized website for various price arches).Most of the data were collected between May and December 2007.3.1.Scope of the study
Chongqing is a commercial and industrial center with average increa rate of the GDP of around 10%per year from 1978to 2006.Average growth rate of investment in construction activ-ities is about 25.4%from 1997to 2006.Chongqing municipality was established on March 14,1997.Covering an urb
an area of 631.35km 2,there were a total of 15districts and 13.11million urban inhabitants in Chongqing in 2006(Chongqing Municipal Bureau of Statistics,2007).
Generally,the aspect of recycling C&D waste mainly depends on the following factors of a district:the scarce of natural aggregates resource,the industrialization level and the population density (Li,2008).Table 3shows that the higher population density in Chongqing and the Netherlands compared with China indicates boom of potential residential buildings demand in Chongqing and the Netherlands.The comparison of the ratio of industrial added
W.Zhao et al./Resources,Conrvation and Recycling 54 (2010) 377–389
381
Table 3
Similarities and differences between the Netherlands and Chongqing in regional factors influencing recycling C&D waste in 2006.Factors
China
Chongqing
Netherlands
Population density (people/km 2)256a 390a 483b Natural aggregates resources
•Sand
•Sand
•Sand
•Gravel:a and riverbeds •Gravel:riverbeds
•Gravel:northa and riverbeds •Rock/mining/mountains •Rock/mining/mountains •No rock/mining/mountains Industrialisation level (%)43c
26.8d
16.79b
Current situation of recycling
•Mixed collection e •Mixed collection f •Separation at source g
•Manual paration
•Manual paration
•A healthy market for recycled products
•High scrap value materials like steel recycled
•High scrap value materials like steel recycled
•Simple landfill (dumping)
•Simple landfill (dumping)
•Financial incentives,such as landfill tax introduced by the Environmental Taxes Act
•Encouraging utilization of energy-saving,recycling and environmental technologies in construction materials
维生素英语•Quantitative limitation and quality control of quarry
•The ban on landfill
a Data source :Population density of the China,Chongqing and the Netherlands from National Statistic Agency of China (2007b).
b Data source :Population density of the China,Chongqing and the Netherlands from Statistics Netherlands (2007).
c Data source :Building industry level of the China,Chongqing an
procedured th
e Netherlands from National Statistic Agency o
f China (2007a).
d Data sourc
e :Building industry level o
f the China,Chongqin
g and the Netherlands from Chongqing Municipal Bureau of Statistics (2007).e Data source :Current
situation of recycling of the China from Zhao and Rotter (2008)and China Academy of Building Rearc
h (2005).
f Data source :Current situation of recyclin
g of the Chongqing from investigation on construction sites and Chongqing Construction Commission (2002).g
Data source :Current situation of recycling of the Netherlands from Ministry of Housing,Spatial Planning and Environment (2001).
value to regional he regional industrialisation level (Lin et al.,2009),implies that although there is no great
potential demand for non-residential buildings compared with nationwide,this demand is higher than the demand of the mature recycling market in the Netherlands.For the scarce of natural aggregates resource,although there are abundant natural aggregates resources in Chongqing and China compared with no rock in the Nether-lands,national and regional regulations have began to encoura
ge recycling and limit amount of quarry.Considering the above three factors,it can be concluded that for Chongqing,a promising prospect for recycling of C&D waste can be achieved (Fig.2).
C&D waste generation and potential demand of recycled mate-rials (aggregates,brick,wood and metal)were calculated bad on the data collected in Chongqing.To evaluate the economic fea-sibility of recycling centers bad on different scenarios (plant type,equipment and land),cost estimation (including fixed costs and variable costs)and investment analysis (IRR,PP and BP)
Fig.2.Location of Chongqing city in China.
were applied.Obstacles of economic feasibility were discusd by comparison of costs and revenues between Chongqing and the Netherlands.
3.2.C&D waste composition and generation rate
There are no data available about the average composition and quantity of C&D waste in Chongqing,since the construc-tion companies until now are not obliged to record and report the qualitative and quantitative characteristics of the waste they generate.In the first approach,rough assumptions were attained through indirect analysis.The C&D waste composition was attained by calculating the arithmetic mean of data from 38construc-tion sites and 28demolition sites.All the sites covered different structures (brick–concrete structure means brick wall have the function of bearing load of residential building (Li and Wang,2005);as frame structure reinforced concrete or steel are ud as load-bearing beams for high-ri residential and commercial buildings;wall structure is a frame structure with shear wall for anti-earthquake performance of a high-ri building)with a floor area of 1.42Mm 2(construction actives of 1.24Mm 2and demolition actives of 0.18Mm 2)and the sites are located in 7districts.
李世默ted演讲
Generation rate is estimated by project managers of construc-tion and demolition sites bad on an estimation of the waste production activities by means of calculating the number of trucks to landfill.The basis to estimate generation of construction waste (Wc )and demolition waste (Wd ),respectively,is the specific gen-eration rate per activity as expresd in Eq.(2):Wc =Fb ×Dc Wd =Fd ×Dd
(2)
where Fb means the floor area of building from Chongqing Sta-tistical Yearbook;Dc means the generation rate of construction waste;Fd means the floor area of demolition from interviews with governors;Dd means the generation rate of demolition waste.3.3.Potential demand of recycled materials
Considering competition of industry solid waste (coal slag and fly ash of coal-fired power plants)as road ba and foundation,their amount should be deducted from the potential demand of recycled
小学生古诗三百首
382W.Zhao et al./Resources,Conrvation and Recycling54 (2010) 377–389
Table4
Assumption and equation to estimate the demand of recycled aggregates.
Items Equation Assumption and reference
Road construction Volume of aggregates for road
construction(Mm2)R=L×W×T/1000L additional roads,in Km(National Statistic Agency of China,
2002–2006)
W average width,and T thickness of ba for II class road work,12and
0.4,in m(Ministry of Communications of the P.R.China,2003)
W and T for below II class road work,6.5and0.15,in m(Ministry of
Communications of the P.R.China,2003)
Recycled aggregates for road work(Mt)Rr=R×D×Sr r D density of ba and foundation for road work,2,in ton/m3(dry
weight)(Road Institute of Ministry of Communications of the P.R.
China,2000)
Sr r substitute rate of recycled aggregate for road construction,50%
(Xiao et al.,2005)
Concrete production≤C30concrete production(Mt)C=E/(Pc×Pc c×Pc30)E cement production,in Mt(Chongqing Municipal Bureau of Statistics,
2002–2006)
Pc Percentage of cement in concrete,12%(Shi and Xu,2006)
Pc c percentage of cement ud to make concrete,60%(Shi and Xu,
2006)
Pc30percentage of concrete ud for≤C30Concrete production,78%
(Anhui Development and Reform Commission,2007)
Recycled aggregates for concrete work
(Mt)
Ra=C×Pa×Sr c Pa percentage of aggregates in concrete,80%(Shi and Xu,2006)
Sr c substitute rate of recycled aggregate in concrete production,
5%(Kartam et al.,2004)
Corrected Rr(Mt)Rr =Rr−Id Id quantity of coal slag andfly ash,in Mt(Chongqing Municipal Bureau
of Statistics,2002–2006)
aggregates for road construction.The potential demand for RA for concrete work after estimating concrete production in Chongqing was calculated.Quantity of RA for road work was estimated by calculating volume of ba and foundation and subtracting the quantity of coal slag andfly ash.Eventually,the estimated demand for total recycled aggregates was calculated.Table4shows the detailed equation and reference for estimation of potential demand of recycled aggregates.3.4.Cost estimation for recycling facilities
The design and capacity choice of a recycling facility is deter-mined by capital costs and has to consi
der the annual waste generation,economy of scale,relative transportation costs,dis-tance of contractors and potential associated tipping fee(disposal fee of landfill).According to Duran et al.(2006),Nunes et al. (2007)and Symonds(1999),a medium scale recycling facilities
Table5
Assumptions for calculating recycling unit cost for a mobile andfixed recycling centers in this paper.
Component Assumption
Fixed recycling facility Mobile recycling facility Background Capacity:100t/h Capacity:50t/h
Working life of equipment:7years(new);4year (ud) Working life of equipment:7years(new);4year (ud)
Work day:300days per year(Duran et al.,2006) Work day:220days per year
Work time:8h/day Work time:8h/day
Operating costs increa at3%per year Operating costs increa at3%per year
Capital costs Construction 10,640D No construction cost
Equipments 642,480D(Nunes et al.,2007) 500,000D
Ud equipment’s capital cost of1/2of the capital cost of ne equipment(Nunes et al.,2007) Ud equipment’s capital cost of1/2of the capital cost of new equipment(Nunes et al.,2007)
“Equipments”including one crushers,one screen t, one loaders “Equipments”including one crushers,one screeners, one loaders
Land cost A land area of4ha(40,000m2)(Symonds,1999) No land costs
A nominal rent of1500D/ha per year(agricultural
rent levels)
Opportunity costs Interest rate:5% Interest rate:5%
Operating costs Labour 6qualified workers;12unqualified workers;1
manager 4qualified workers;8unqualified workers;1 manager
Monthly wage(Chongqing price information center) Monthly wage(Chongqing price information center)
Energy Electricity:0.04D/kwh(Chongqing price information
center) Electricity:0.04D/kwh(Chongqing price information center)
Disposal “Disposal”:20%of quantity of input(Nunes et al.,
2007); “Disposal”:20%of quantity of input(Duran et al., 2006);
Average tipping fee of landfill of0.5D/t(Commodity Prices issued documents)and transportation cost to landfill of0.5D/t Average tipping fee of landfill of0.5D/t(Commodity Prices issued documents)and transportation cost to landfill of0.5D/t
Other “Other”including maintenance with new equipments
(6%of equipment investment),maintenance with ud
(1.2times the maintenance cost of new equipment),
insurance(1%of equipment investment) “Other”including maintenance with new equipments(6%of equipment investment), maintenance with ud(1.2times the maintenance cost of new equipment),insurance(1%of equipment investment)and transport of facility
