Integrated construction waste management, a holistic...

Scientia Iranica A (2016) 23(5), 2044{2056

Sharif University of TechnologyScientia Iranica

Transactions A: Civil Engineeringwww.scientiairanica.com

Integrated construction waste management, a holisticapproach

M.M. Mortaheb� and A. Mahpour

Department of Civil Engineering, Sharif University of Technology (SUT), Tehran, Iran.

Received 24 November 2015; received in revised form 1 February 2016; accepted 16 April 2016

KEYWORDSIntegratedconstruction wastemanagement;Sustainabledevelopment;Constructability;Construction anddemolition waste;construction wastereduction.

Abstract. The objective of the present study is to depict an inclusive ConstructionWaste Management (CWM) plan looking at the total project life cycle. This holisticapproach is called Integrated Construction Waste Management (ICWM). This researchprogram has been conducted through several consecutive academic dissertations atCivil Engineering Department of SUT and was �rstly aimed to identify waste sourcesthroughout project life cycle. Concurrent research e�orts were focused on project deliverymethods evaluation, e.g. contract type e�ect on waste generation amount along withappropriate guidelines/incentives development that could promote ICMW. These studieswere conducted via �eld observations and questionnaire surveys where respondents wereeducated, skilled, and experienced construction industry experts. The research �ndingsindicate that construction waste origins/processes should be determined separately duringthe life cycle of construction projects to devise exclusive solutions accordingly. Furthermore,cost-plus contract, which is common in local residential projects in Iran, is identi�edas an improper contract type from construction waste generation standpoint. Incentivebased programs, project stakeholders training, salvage plan establishing for all materialsbefore project initiation, and apt documentation for future CWM planning are identi�ed ase�ective/practical ICWM solutions. Finally, it is concluded that thriving ICWM is goingto be a teamwork result rather than responsibility of a sole stakeholder, e.g. contractor.© 2016 Sharif University of Technology. All rights reserved.

1. Introduction

Construction industry plays a major role in enhancingcompetitiveness and prosperity in the world economy.The design, construction, operation, and utilizationphases of the built environment have important eco-nomic as well as sustainability e�ects. Modern ande�cient built environment is a key driver of produc-tivity and growth in every economy. Therefore, theconstruction industry is facing a challenge in deliveringthe built environment in an e�ective and optimized

*. Corresponding author. Tel.: +98 21 66164266;Fax: +98 21 66013201E-mail addresses: [email protected] (M.M. Mortaheb);mahpour [email protected] (A. Mahpour)

manner, in order to maintain its share in the economywhile coping with the global sustainability rules andregulations. The construction industry has signi�cantimpact on the environment during execution of everyphase of the project's life cycle. It consumes enormousamounts of raw materials and respectively producesconsiderable waste during construction, renovation,and/or demolition phases of the project. Studiesestimate that construction industry consumes around aquarter of all raw materials used in the world economy.It also produces up to one third of total land�ll wasteswith a 1:2 ratio of construction to demolition waste [1-3]. Only a fraction of the produced waste is currentlyrecycled or reclaimed. These statistics imply the im-portance of CWM and, most recently, growing concernsabout the sustainability of construction activities have

M.M. Mortaheb and A. Mahpour/Scientia Iranica, Transactions A: Civil Engineering 23 (2016) 2044{2056 2045

brought the issue of Construction Waste Management(CWM) to the fore. CWM is any e�ort, includinglegislation, supervision, �ning or reward based pro-grams, etc., done in order to reduce, minimize, orcontrol construction waste generation [4]. Similarly,construction waste minimization is planning for re-ducing avoidable construction waste during di�erentphases of construction projects, especially constructionphase [5].

ICWM is balancing the environmental demandsof a project with the economic ones, which re ects cur-rently accessible CWM solutions like reduction, recy-cling, reusing, incineration, land�lling, and compostingthat are being investigated and developed in di�erentparts of the world. In other words, ICWM is a com-prehensive construction waste prevention, recycling,composting, and disposal program. This program canbe done by urban and project managers via legislation,more strict supervision, �ning or rewarding policies,and many other methods [6-8]. Construction industry,by its very nature, while contributes to the economicaspect of sustainable development, is detrimental tosustainable environment. The aim of this research isto integrate the previous studies done by authors onidenti�cation, management, and reduction solutions ofconstruction waste [9-12]. By enhancing the e�ciencyin using resources, the construction industry can play acentral role to promote sustainable growth and develop-ment. Sustainable development is de�ned as \Meetingthe needs of the present, without compromising theneeds of future generations" [13]. However, policymakers and practitioners tend to forget the other twodimensions of sustainable development { environmentaland social { during planning and implementation ofconstruction projects [14]. In developed countries,standards, guidelines, and regulations have been de-signed to address the issue of CWM. However, despiteconsequences and adverse impacts that excessive pro-duction of Construction and Demolition Waste imposeson sustainable development, little care has been givento the implementation of CWM practices in unde-veloped and even developing countries. As a result,the construction industry has not made satisfactoryprogress towards achieving sustainability goals. Forinstance, the ultimate product of today's constructionindustry is the built environment designed and con-structed without any consideration for dismantling andreuse at the end of its life cycle [15].

Construction waste, as disposed or not usefulmaterials during execution of projects, is one of thecurrent serious environmental concerns. High amountsof material wastage exert several detrimental e�ectson economy, environment, and society. Lack of com-prehensive and practical frameworks to help projectmanagers implement such holistic plans in construc-tion projects, especially in developing countries where

traditional construction methods are common, is stillpalpable. Construction waste can be addressed in twodi�erent ways, i.e. waste minimization and waste man-agement, during the project life cycle from initiation todemolition.

1.1. Literature reviewKern et al. (2015) conducted a multiple-regression-based study and evolved a model estimating theConstruction Waste Generation (CWG) in high-risebuildings construction in Brazil. In this research, theproduction system and design process are deemed to besalient in uential parameters in estimating CWG [16].S�aez et al. (2015) investigated the total oor area ofthe project and number of dwellings simultaneouslyand studied several newly built residential buildings.They proposed a novel quanti�cation model in termsof volume and weight for CWG in the Mediterraneanbuildings [17]. Ding and Xiao (2014) quanti�ed Con-struction and Demolition Waste (C&DW) generationin buildings in Shanghai, China, by scrutinizing theoutcomes of structure design and a�liated structurecodes in several decades on uctuations of CWG andstructure type [18]. Based on mass balance principlefor construction, Li et al. (2013) generated a modelquantifying waste generation per gross FA (WGA)in China. In this model, WGAs for materials arecomputed based on the purchased amount and wasterate of materials. In addition, the WGA for minorquantities of materials is obtained as a percentageof total CW. This suggested model is applied toconstruction of a residential building in Shenzhen,China [19]. Banias et al. (2011) conducted a case studyof �ve apartment buildings in Thessaloniki, Greece, inorder to quantify twenty one distinct C&DW streamsfor di�erent sorts of buildings including industrial,residential, o�ce, and commercial. With respect toeconomic and environmental criteria, a web based de-cision support system application, called Decon RCM,empowers user to optimize end of life managementalternatives using mathematical programming [20]. Aquantitative model is developed by analyzing morethan twenty buildings in a Spanish case study by Llatas(2011). This model promotes prevention and recoveryof CW, and permits to �nd the origin of the waste andadapt other alternative procedures eliminating haz-ardous waste and reducing CW. Furthermore, it makesestimation of C&DW during the design phase possible.By analytical expressions based on the factors obtainedby studying the buildings, a systematic structure of theconstruction process and a system for waste divisionare engendered as well. Results imply that prosperousimplementation of the model in construction projectswill yield enhancement of the opportunities of C&DWreduction and recovery [21]. Cochran and Townsend(2010) applied a materials ow analysis approach

2046 M.M. Mortaheb and A. Mahpour/Scientia Iranica, Transactions A: Civil Engineering 23 (2016) 2044{2056

and used Building Materials (BMs) and typical wastefactors used for BMs supplying to quantify C&DWgeneration in USA [22]. Katz and Baum (2010)estimated CWG in residential construction sites bymeans of a method they developed. They researchedin three steps: �eld observations, data collection, anddevelopment of the model. The results are believedto be helpful for CWM practices akin to enforcementsystems or taxation [23]. Udwatta et al. (2015)determined e�ective approaches to eliminate and/orminimize waste generation in construction projects.Their �ndings revealed 26 critical solutions for wastemanagement, such as using construction technologiesand proper selection of materials [24]. Butera et al.(2015) quanti�ed the environmental impacts of C&DWutilized in road construction and compared the resultsof the study with land�lled C&DW. The results indi-cated that using C&DW in road construction was lessdetrimental to environment than land�lling them [25].

1.2. The research gapExamining the available literature and consulting theexperts show that whilst there are several articles,instructions, and manuals addressing the issue of con-struction waste, waste management programs are notintegrated e�ectively into most of the constructionprojects. This is partly because current policies,procedures, and methods do not address the issueholistically. They do not take all aspects of a project,i.e. all its phases, work resources, and activities, intoconsideration. Lack of practical frameworks to helpproject managers to implement the concepts and prac-tices of CWM in projects is a gap that has to be�lled through research and development. Therefore,more holistic studies are needed to address the con-cepts and principles of CWM. This paper provides anoverview of the research endeavors aimed at enhancingthe state of knowledge and practice in devising andimplementing of appropriate construction waste mini-mization and management practices in the constructionindustry. In this context, management of waste isde�ned as eliminating waste to the maximum possibleextent (eliminating avoidable waste) by minimizingwaste where feasible and reusing materials that mightotherwise become wasted. Solid waste managementpractices have identi�ed reduction, recycling, and reuseof wastes essential for sustainable management ofresources. Comprehensive studies conducted by theauthors during the last several years include, but arenot limited to, the following topics.

1.2.1. Construction waste management: An approachto improve construction productivity

The objective of this study [26] was to enhance theunderstanding about CWM practices and improve con-struction productivity as well as promote sustainable

development. Through a comprehensive literature re-view, concepts such as project productivity, sustainabledevelopment, whole life cycle paradigm, and hierarchywere analyzed. The review of literature shows that theamount of construction waste, even in most developedcountries, is high. Nevertheless, it is found out thatin the developed world, signi�cant e�orts have beendedicated to the development of appropriate policiesand regulations as well as manuals and instruction onthe CWM topic.

Following the review of related literature, a frameof reference to shift the current paradigm in industry to\construct with minimum waste" was developed,as displayed in Tables 1 to 3. Furthermore, Table 4represents the results of a successful �nancial incentivebased scheme implemented in Hong Kong, China.Finally, Table 5 shows the results of elasticity analysisof construction materials wastage reduction in Tehran,Iran. This paradigm identi�es and discusses CWMconsiderations through whole project life cycle, i.e.from feasibility studies to the start-up and operationof the �nally built structure.

CWM Paradigm is the frame of reference bywhich decision makers of the project would e�ectivelycontribute to decreasing the amount of waste generatedthrough construction activities, which will in turnimprove productivity of the project. Table 3 displaysthe summary of the survey. This summary tablepresents maps of CWM areas of concentration andproposes strategies for the project life cycle phases. Aconcentration area is a topic/issue that is of specialimportance when considering CWM, while proposedstrategies, methods, tools, and techniques refer tospecial practical recommendations with regard to eachconcentration area.

It is recommended that constructors apply thisframe of reference to optimize material usage. It shouldbe noted that the implementation of this frame of refer-ence requires no additional planning and/or resources.In addition to the introduction of the paradigm, amodel based on the common lexicon provided byProject Management Body Of Knowledge (PMBOK)was developed. This model is shown in Table 2and utilizes the same terminologies of PMBOK Guidelexicon. This model is intended to serve as a standardfor project managers to implement CWM program inconstruction projects. In the process of developing thismodel, �rst, the feasibility of adding CWM concepts toEnvironmental Management knowledge area was exam-ined. However, the scope of necessary changes as wellas the importance and universality of CWM principlesrequired the principles of CWM to treat as a separateknowledge area of construction extension. PMBOKguides, so far, have not addressed the importance ofconstruction waste reduction or signi�cance of CWM.Ultimately, this knowledge area can be suggested to


Table 1. Mapping of CWM considerations and strategies for the phases of the project's life cycle.

Projectphases

Constructionareas

Proposed strategies,methods, tools, and

techniques

Feasibilitystudies

CostCost-bene�t analysis, value engineeringLife cycle costingRecycled materials market analysis

Time

Deconstruction parallel to design/engineeringProper schedulingSmarter, not slower, work (avoid complexity inworkers' duties)

QualityAssess and estimate the quality of recycled materialsAssess and estimate the quality of �nal products(structures)

Design andengineering

Design/engineering philosophy

Adoption of modern design systems,e.g. modular designUse of standard and simple shapes and sizes

Constructability analysis of design Design construction integrationProvide accurate, understandable, reliable blueprints

Design change and modi�cationsAvoid frequent changesSelect change options with minimum demolitionand rework

Material construction Use prefabricated membersUse recycled materials

Estimating materials requirements

Provide accurate destination for amount ofmaterial deliveryProvide accurate destination for time ofmaterial delivery

Job-site layout

Allocate adequate, appropriate space to CWM equipmentAllocate adequate, appropriate space to collecting binsAllocate adequate, appropriate space to inventoryProvide easy-access routes between inventory and workshop

Procurement

Materials and source selection Use durable materialsUse local resources

Supplier selection and management Stipulate take-back policiesRequire reduction of packaging materials

Contractor selection and management

Represent waste reduction requirements in the contractRequire the contractor to submit a CWM PlanRequire the contractor to document their waste reductionIncorporate the CWM Plan into the contractor's QC/QA

Equipment and machinery selectionConsider waste characteristicsConsider market speci�cationsConsider job-site space and layout

Ordering management Order in coordination with design/engineering unitDeliver just in time


Table 1. Mapping of CWM considerations and strategies for the phases of the project's life cycle (continued).

Projectphases

Constructionareas

Proposed strategies,methods, tools, and

techniques

Inventory management

Allocate appropriate space and position to inventoryProvide proper sheltering against weather andhuman factors

Provide easy-access routes to inventory

Transportation and on-site handling Hire experienced and reliable haulersMaintain proper on-site supervision

Construction/execution

Construction and demolition methodsPrefabricationDeconstructionImproving e�ciency of current methods

Mistakes, errors, and rework

Provide clear, reliable blueprintsMaintain proper on-site supervisionUse advanced, reliable technologiesPerform periodic service and repair equipmentKeep job-site organized and safe

Job-site activities plan CWM PlanCWM site activities plan

Job-site supervisionTroubleshooting and on-site training/educationChange requestsPrepare periodic performance reports

Training and educationArrange and manage training sessionsProvide and distribute easy-to-understand instructionsDesign and set job-site instructive signs and marks

Quality control Quality control/assurance of recycled materialsQuality control/assurance of �nal products (structures)

Prevent construction waste generation

Devise merits for reducing construction waste anduse elasticity as a tool for control and preventconstruction waste generation

Start-up Job-site �nal clean-up Collect unused materials after constructionOperation/ Renovation and repair Deconstruction and careful dismantlingutilization Reuse and recycle used materials

Table 2. Mapping of CWM processes of the process groups (format adopted from PMBOK* by Project ManagementInstitute).

Knowledge area Process groupsInitiating Planning Executing Controlling Closing

Constructionwaste

management

Wasteidenti�cationand analysis

Wastemanagement

planning

Trainingand educational

programs

Wastemanagement

program control

Wastemanagement

program administrationand records

Resourceplanning

Waste managementplan execution


Table 3. The degree of in uence of constructability ideas on productivity.

No. Criteria Score (out of 5)1 Considering appropriate material sizing 4.62 Design to simplify installation 4.53 Design according to available resources and skills 4.54 Providing clear details and technical speci�cations 4.35 Evaluating project site location and environment 4.26 The use of modeling and simulation to avoid di�culties during construction 4.17 Evaluation of the possible juxtaposition of di�erent materials due to allowable tolerances 4.18 Encouraging for standardization and increasing modular activities 4.0

9 Considering the location of the warehouse to minimize the need for handlingmaterials at project site

4.0

10 Design to minimize the work on levels below the ground surface 4.011 Design to improve and facilitate prefabrication 4.012 Considering the interaction of climate with construction materials and methods 4.0

Table 4. Summary of the incentive based method.

Stage

Cost saved onpurchasingmaterial

($)

Cost savedon waste

generation($)

Percentagesof waste

generationsaved

1 173500 3230 42 173500 7580 93 173500 19030 23

Table 5. Results of elasticity analysis of �nancialincentive in Tehran, Iran.

MaterialAveragewastage

(%)

Averageelasticity

Economicincentivegrowth

(%)

Relativewastage

reduction(%)

Rebar 1.358 0.424 1 31.22Concrete 3.793 0.815 1 21.49

Brick 6.049 0.684 1 11.31Cement 8.403 0.923 1 10.98

be added to the future release of PMBOK Guide asan extension. CWM knowledge area includes theprocess required to ensure that construction projectsare executed with appropriate care to reduce the wastematerials headed to land�lls. The proposed modelrecognizes seven processes in CWM knowledge area:waste identi�cation and analysis, waste managementplanning, resource planning, training and educationalprograms, waste management plan execution, wastemanagement program control, and waste managementprogram administration and records. In Table 2, theseprocesses are mapped into �ve major process groups ofinitiating, planning, executing, controlling, and closing.

The model is speci�cally developed for projects

where CWM is recognized as a major program of theproject portfolio similar to other programs such asthe Health and Safety program. Finally, as a partof this research, a study aimed at characterizing thestatus of construction waste production and manage-ment in Tehran metropolitan area was conducted. Inthis study, a questionnaire including 59 questions wasprepared using Likert scale and was distributed toconstruction experts. The experts were supposed toassign one of the scores of 0, 0.25, 0.50, 0.75, or 1to each question. Then, the average of the scores ofthe same criterion obtained from reliable questionnaireswas calculated and �nally, a set of 59 criteria wereprioritized. The criterion which gained the highestscore was ranked the �rst and so on. The case study(Tehran metropolitan area) and the follow-up analysisled to the identi�cation of a set of measures that couldimprove the current situation. Based on the �ndingsof this analysis, in order to implement CWM principlesin Iran's Construction Industry, the government shouldset out rules and provide instructions on the issue,while constructors must design structures for minimumwaste and adopt modern construction methods likeprefabrication or the mentioned economic merits.

Through several case studies, the factors a�ectingconstruction materials waste generation during supplychain (mainly perishable like Ready-Mix Concrete(RMC) and/or Hot-Mix Asphalt (HMA) at the con-struction site were carefully investigated and ranked.The 10 most important ones were found to be:

� Waste generated due to lack of modular or standardconstruction;

� Waste generated by non-recyclable packaging mate-rials;

� Using low quality building utility components thatwould require early-age renovation;


� Waste generated by untrained or unskilled work-force;

� Lack of an integrated CWM program in the projectadministration;

� Using low quality construction materials;

� Waste generated during transport to site or insidethe site due to improper packaging;

� Waste generated by cut-to-�t due to design require-ments and/or disorders;

� Waste due to over-stocked bulk materials at the site;

� Waste generated because of utilizing old or impreci-sion tools or equipment.

1.2.2. E�ect of constructability studies onconstruction waste generation

During the construction of high-rise buildings, theproject team issues such as changes, additional costsof duplication, lack of technical speci�cations in plans,safety, and delays may arise. One of the most e�ectiveways to avoid these issues is constructability evalua-tion at the appropriate stages of project. There areseveral de�nitions for constructability. For instance,it has been de�ned as the optimal use of knowledgeand practical experience in planning, design, andprocurement in order to achieve the overall goal ofthe project [27]. Numerous studies have investigatedthe impact of conducting constructability reviews inconstruction projects. A study conducted by theConstruction Industry Institute (CII) [28] showed thatimplementation of constructability reviews in �ve dif-ferent projects has reduced the project duration by 11to 30 percent. In addition, analysis of data from severalprojects has shown that by using constructability, timeis reduced without resulting in any signi�cant costsincrease [29].

The objective of another study [30] was to exam-ine the e�ectiveness of constructability and productiv-ity reviews in high-rise building projects. Interviewswith experts and questionnaires were used as themain tools to gain insight into this matter. Thestudy �rst investigated the opportunity to implementconstructability reviews in the design phase of high-rise building projects. In the design phase, the con-structability review should focus on the following areas:

� Evaluating project site location and environment interms of architectural textures;

� Designing to minimize the work on levels below theground surface;

� Designing to simplify installation;

� Encouraging standardization and increasing modu-lar activities;

� Designing to improve and facilitate prefabrication;

� Utilizing modeling and simulation to avoid di�cul-ties during construction [31];

� Evaluating the possible juxtaposition of di�erentmaterials due to allowable tolerances;

� Planning to avoid problems in sequential activities;

� Considering the location of the warehouse to mini-mize the need of handling materials at project site;

� Designing according to available resources and skills;

� Considering appropriate material sizing;

� Providing clear details and technical speci�cations;

� Considering the interaction of climate with con-struction materials and methods.

Based on the areas of constructability reviewsduring the design phase, a questionnaire was preparedto survey the impact of constructability reviews onconstruction productivity in high-rise buildings. Thisquestionnaire used Likert scale and was distributedto 42 construction experts. The objective of thissurvey was determining the degree of in uence ofconstructability on productivity. The experts wererequested to assign one of �ve scores from 1 to 5 to12 criteria based on their experience and judgment.The responses to the questionnaire were analyzed usingthe average index method. Table 3 summarizes thesurvey results. The survey results indicated that, ifconducted during the design phase, constructabilityreviews could enhance the productivity in high-risebuilding projects. It is recommended that, prior tothe initiation of a project, the project managementteam develop appropriate guidelines and checklists forconducting constructability reviews.

Surveys show that the two main barriers toimplement e�ective ICWM are:

� Lack of culture for saving the resource and/oroptimum use;

� Lack of de�ned recycling scheme in the projectadministration.

Experts recommended strategies be developed inorder for:

� Constructability Analysis to be performed at designstage;

� Industrial construction to be used and build qualityto last longer;

� Reuse or recycle to be done when demolishing.

1.2.3. Materials waste control through elasticityanalysis and incentives

A quantitative study was done in order to determinethe priority of saving the resources and/or their opti-mum use.


Firstly, the concept of elasticity could be proposedas a proper tool to devise e�ective policies. Thisconcept is used to derive the results of another studyby the authors that is displayed in Table 5. Accordingto the de�nition of elasticity [32] for the independentvariable of X and dependent variable of Y , elasticityof variable Y is calculated based on Eq. (1):

EY C =�@YY

��@CC

� =��YY

��CC

� : (1)

Several researchers have investigated the applicabilityof this concept in various �elds such as supply-demandadjustment, i.e. controlling of fuel consumption byanalyzing the sensitivity of fuel consumption to itsprice, and have stated that this sensitivity could bedetermined by calculating EFP according to Eq. (1),where dependent variable is F or fuel consumptionand independent variable is P or fuel price [33,34].Furthermore, the concept of elasticity is assumed tobe a good managerial tool to make decisions related towaste management, which persuaded the authors to useit in determining the most sensitive material to increas-ing �nancial incentive (summarized results in Table 5).For example, this concept has been studied in orderto reduce the wastage of paper, too. Mansikkasaloet al. (2014) provided a critical survey of existingeconometric analyses of supply and demand elasticityin recycled paper market and suggested Eq. (2) toestimate the supply of recycled paper [35]:

RS = �0 + �1:PR +MX

1=2

�1:F1 + y: (2)

Eq. (2) is developed to manage paper waste and toanalyze the recycled paper supply, where RS is recycledpaper supply, PR is recycled paper price, Fl is thevector containing any additional independent variablesincluded in the demand and supply equations, y is theerror term, and �1 is the coe�cient of the variablePR [35]. The concept of elasticity can be e�ectivelyused in CWM, too.

Secondly, economic tools can be implementedto prevent or reduce construction waste generation.One of the important methods of economic tools ispayment of incentive [12,36]. Tam and Tam (2008)developed a creative method to reduce constructionwaste generation in Hong Kong. In this proposedincentive based model, which is implemented in 3 levelsas shown in Figure 1, the results mentioned in Table 4are derived [36].

The amount of reward (�R) in this study is givenin Eq. (3):

�R = Ct:R%; (3)

where R% is determined from Figure 1 and Ct is totalcost saved [36].

Figure 1. Stepwise incentive scheme (Ct: total costsaved, Q%: material quantity percentage saved, and W%:waste percentage saved).

Thirdly, a combination of �nancial incentive andits managing by means of elasticity can be proposed.Such study is done in Iran by authors and economicincentive is proposed to persuade contractors in orderto reduce wastage of bulk materials. To do this,a questionnaire was prepared to gather quantitiesof the wastage amount of four commonly used bulkmaterials including rebar, concrete, brick, and cementin Tehran. Thirty two residential building projectswere studied and wastage of these bulk materials wascollected through �eld observations and measurement.Afterwards, sensitivity of wastage of studied materialswas investigated by using elasticity concept. Theresults of elasticity analysis showing the e�ect of 1%increase in the payment of a �nancial incentive onwastage reduction of cement and 3 other materials aredepicted in Table 5 [9].

According to the \average elasticity" amounts inthe third column, increase in this kind of �nancialincentive is mostly e�ective on reduction of cementwastage.

2. Other research e�orts

There are several recent research e�orts focusing onCWM. An overview of these research e�orts is pre-sented below:

a) Since di�erent regulations of contracts are assumedto a�ect the behavior of contractor in wastingmaterials, this parameter was studied. Througha questionnaire survey, wastage of materials inprojects employed by cost-plus or lump-sum con-tract was investigated. This questionnaire askedcontractors to determine the contract type andwastage percent of materials in their projects inorder to understand the impact of contract typeon the amount of construction waste generated inresidential projects. The objective of this studywas to utilize �eld studies and surveys in orderto enhance the understanding about the impact ofcontract type on the amount of construction wastegenerated in residential projects. The study alsoinvestigated the impact of contract types on the


Figure 2. Comparison of the amounts of waste generatedin lump-sum and cost-plus projects.

waste minimization and management practices thatpractitioners adopted in residential projects. Theearly �ndings of this research indicated that thecontract type had an apparent e�ect on the amountof construction waste produced in constructionproject. Figure 2 shows a comparison betweenthe amounts of waste (as a percentage of thetotal material consumption) generated in Lump-Sum and Cost-Plus projects. In the later stagesof this research, the data would be statisticallyanalyzed to determine whether the e�ect of contracttime on the amount of waste is signi�cant. Theresults will be interpreted in an e�ort to identifythe key factors contributing to these di�erences.The averages for wastage of materials in the studiedprojects are calculated and shown in Figure 2.

b) Appropriate guidelines should be established inorder to incorporate waste minimization and man-agement considerations in project planning andpermitting process. Preparation of a CWM Planshould begin in the early stages of project develop-ment to facilitate e�cient and timely managementof the waste that is likely to be created duringthe construction process. It is essential for theparties involved in a construction project to esti-mate the amount of waste in a construction projectand accordingly plan and control the process ofmanaging the generated waste. If developed atthe early stages of a project, CWM Plans willhelp project stakeholders establish goals for themanagement of construction waste by focusingupon waste minimization, reuse, and recyclingopportunities. This will promote sustainable devel-opment, environmental protection, and e�cient useof resources. A questionnaire was prepared basedon Likert scale and was delivered to 50 constructionexperts. The objective of this study was to developguidelines on preparation and evaluation of CWMPlans in the early stages of the permitting ofconstruction. The experts were requested to assignone of �ve scores from 1 to 5 to criteria based ontheir experience and judgment. A model will beprovided to estimate the volume of waste that is

expected to be generated during the constructionperiod. Appropriate measures will be introducedto develop and evaluate the plans that are designedto minimize and/or manage the generated wasteduring the construction process. The permittingagencies such as municipalities can use the outcomeof this research to integrate the development of anappropriate CWM Plan as a critical part of thepermitting process that all construction projectsshould pass.

c) Developing an ICWM framework by ranking mar-ket prices of waste materials helps to evaluatesalvaging of building materials for recycle or reuseand incentives o�ered in order to design and con-struct sustainable buildings, infrastructures, andcommunities that are focused on various meansand methods for improving sustainability to ensurethe future of the built environment. In order toconduct this study, a list of 21 criteria in uencingthe amount of generated waste was derived fromreviewed literature. Then, a questionnaire surveywas done in which 65 construction experts tookpart. This questionnaire survey was arranged inLikert scale and the experts were supposed tochoose one of the scores of 1, 2, 3, 4, or 5 for eachcriterion. Data was analysed using AHP. Then, theaverage of scores for each criterion was calculatedand the criteria were ranked according to their �nalscores. These criteria were categorized in 3 phasesof initiating, design, and construction. Determiningappropriate contract along with cooperation ofdesign and construction phases was identi�ed as thekey factor of controlling construction waste gener-ation. Solid CWM policies can lead to sustainablemanagement practices.

3. The waste generated in demolition phase

The goal is to identify market sources for reusableand recyclable materials generated from C&D projects.Private-sector experience has successfully demon-strated that deconstruction and salvage of buildingmaterials are viable alternatives to demolition andland�ll in many commercial markets. Under theappropriate conditions, it is realistic to expect morethan 75% of a building's content to be salvaged forreuse or recycling [26].

Figure 3 shows the constituents of C&D waste inTehran, Iran.

4. Discussion

The target of this study is to depict an inclusive CWMPlan looking at the total life cycle of the project. Thisholistic approach was called Integrated Construction


Figure 3. Constituents of construction and demolitionwaste in Tehran, Iran [26].

Waste Management (ICWM). Construction waste, dis-posed or not useful material during construction ofprojects, is one of the most recent environmental con-cerns. ICWM is balancing of environmental demandsof a project with economic ones. In other words, ICWMis a comprehensive construction waste prevention, re-cycling, composting, and disposal program. One basicnecessity of life for human prosperity is maintaining aclean environment; yet the evidence from this analysissuggests that no progress has been made in address-ing problems of Municipal Solid Waste Management(MSWM) as the population grows. Physical expansionof the metropolitan region through urban sprawl hasoccurred without complementary expansion of SolidWaste Management (SWM) services and, indeed, mostother services. Evidence from the �eld suggests thatthousands of people in the study area depend on wastemanagement policies. In this paper, previous studiesby authors, which were related to identi�cation, man-agement, and reduction solutions of construction waste,are elaborated on, and results of each are discussed.

For example, a model is mapped in Table 2. Thismodel is intended to serve as a standard for projectmanagers to implement CWM program in constructionprojects. In the process of developing this model,�rst, the feasibility of adding CWM concepts to envi-ronmental management knowledge area was examined.However, the scope of necessary changes as well asthe importance and universality of CWM principlesrequired the principles of CWM to be treated as aseparate knowledge area of construction extension.

Furthermore, Table 3 summarizes the degreeof in uence of constructability ideas on productiv-ity. Results indicate that, if conducted during thedesign phase, constructability reviews could enhancethe productivity in high-rise building projects. It isrecommended that, prior to the initiation of a project,the project management team develop appropriateguidelines and checklists for conducting constructabil-ity reviews.

Since so far no e�ective policy is implemented in

Iran to reduce construction waste (some regulationsare devised just for demolition waste), authors decidedto determine the most wasted material and de�ne a�nancial incentive to control its wastage. As declaredin Section 1.2.3 and Table 5, a �nancial incentiveequal to demolition charge will be e�ective in reducingcement waste.

The results of other studies by authors and otherrecent studies can be found in the paper and especiallyin Section 3. To assert brie y, lump-sum contract ismore justi�able than cost-plus contract in order toreduce materials waste.

Determining appropriate contract along with co-operation of design and construction phases is identi-�ed as the key factor of controlling construction wastegeneration. Solid CWM policies can lead to sustainablemanagement practices.

5. Conclusions

In this paper, an overview of the �ndings of a broadlocal research program that has been undertaken overthe last several years is presented. The objectiveof this research program has been identifying and/ordeveloping appropriate waste management proceduresand practices that can be implemented throughout thelife cycle of the construction project, from planning,design, and construction stages to the renovation ordemolition phases.

ICWM can be addressed in two di�erent ways;�rst, waste minimization and second, waste manage-ment; during the whole life cycle of the project, frominitiation to demolition. The aim of the �rst phaseof this research program was to identify the sourcesof waste throughout the supply chain of constructionprojects and determine appropriate waste managementpractices to control the generated waste. Severalfactors were carefully investigated and ranked. In thesecond phase, several comprehensive studies were con-ducted in order to �nd e�ective ways for CWM duringconstruction, renovation, and/or demolition phases ofthe projects. Some CWM concepts are suggested to beadded to Project Management Knowledge Area (seeTable 2) in order to manage and reduce constructionwaste generated. These suggestions are to be approvedby PMBOK Guide board.

This research program has been expanded overthe past few years and, at present, there are severalongoing research e�orts focusing on CWM. The re-search is being conducted to understand the impact ofproject organization factors such as contract type onthe amount and characteristics of the waste generatedin construction projects. There is another researche�ort focusing on creating appropriate guidelines toincorporate waste minimization and management con-siderations in project planning and permitting process.


It is imperative to conduct more studies onCWM. These research e�orts should especially focuson the construction industry in developing economies,where construction works will remain a major economicactivity. In future research projects, sophisticatedmodeling and simulating techniques should be usedin conjunction with surveys and case studies in orderto enhance the understanding about e�ective ways toapproach CWM.

The main research recommendations are the fol-lowing:

� It is very important to establish a salvage plan forall materials before starting a project;

� ICWM Plan and its complementary supportingdetails should provide the roadmap for the executionof the CWM program (for example, it is suggestedto convince contractors by economic incentives tominimize the amount of cement they waste duringthe construction phase of the buildings [9]);

� Achievement of ICWM incentive goals should beincluded in the project charter;

� ICWM program should require workforce to workmore e�ciently and neatly;

� Administration and closure should include docu-menting project results to formalize acceptance ofthe ideal �nal result by the project management,governmental authorities, and organizations approv-ing the implementation of ICWM. It includes col-lecting program records; ensuring that they re ect�nal speci�cations; analyzing success and e�ective-ness of the program, and the lessons learned; andarchiving the document for future use;

� Municipal authorities can persuade contractors toreduce the amount of construction waste they gen-erate by means of economic rewards;

� Documented waste management performanceshould become another pillar of ICWM; and

� Last but not least, educational materials, manuals,and instructions are to be prepared and documentedfor extensive use.

The following are the bene�ts of the discussedintegrated ICWM Plan:

� Salvaged building materials o�er many opportuni-ties to owners, consultants, and contractors for reuseor recycling, including:- Lower material costs than virgin (e.g., crushed

concrete in place of virgin aggregate);- High-quality building materials;- Materials that may match historical building

elements; and- Reduced waste disposal costs.

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Biographies

Mohammad Mehdi Mortaheb received his PhD inConstruction Materials and Management from Univer-sity of Kentucky, Lexington, KY, USA, in 1990. He hasbeen a member of scienti�c committees of several na-tional and international conferences related to projectand construction management and supervised manygraduate students doing their master degrees at SharifUniversity of Technology (SUT) and other universities.He has been active in directing and managing di�erent


real projects, especially in pipe line, oil, gas, andpetrochemical industries of Iran, over the last 42 years.He has been always a bridge between academy andindustrial world.

Amirreza Mahpour received his BSc degree fromAmirkabir University of Technology (AUT), Tehran,

Iran, in 2014. He has been MSc student of ConstructionEngineering and Management in Civil EngineeringDepartment of Sharif University of Technology (SUT),Tehran, Iran, since 2014. His research is within the �eldof construction and demolition waste management anddevising policies to control and reduce this kind of solidwaste.

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