Current and Emerging Construction Waste Management Status, Trends and Approaches

C H A P T E R

19 Current and Emerging Construction Waste Management Status, Trends and Approaches Mohamed Osmani*, Paola Villoria-Sa´ez† *School of Architecture, Building and Civil Engineering, Loughborough University, Loughborough, United Kingdom † School of Building Construction, Universidad Polit
ecnica de Madrid, Madrid, Spain

O U T L I N E 1. Introduction

366

2. Concept and Definitions

366

3. Context

368

4. Construction Waste Composition and Quantification

370

5. Construction Waste Source Evaluation

371

6. Construction Waste Management and Minimization Approaches

373

7. Construction Waste Minimization and Management Tools, Methodologies, and Technologies 374

Waste https://doi.org/10.1016/B978-0-12-815060-3.00019-0

7.1 Preconstruction Stage: Forecasting and Designing Out Waste 375 7.2 Construction Stage: On-Site Construction Waste Management 376 7.3 End-of-Life Waste Recovery, Recycling, and Circularity 377 8. Construction Waste Management Challenges and Incentives

377

9. Discussion and Conclusions

378

References

379

365

Copyright # 2019 Elsevier Inc. All rights reserved.

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19. CURRENT AND EMERGING CONSTRUCTION WASTE MANAGEMENT STATUS, TRENDS AND APPROACHES

1 INTRODUCTION The built environment consumes more natural resources than necessary and therefore generates a large amount of waste. A study by the World Resource Institute of material flows in a number of industrialized countries showed that one half to three quarters of the annual material input to these societies was returned to the environment as waste within one year [1]. Failure to consider the wider implications of economic development has led to a global environmental crisis driven by wasteful material resources. This situation trigged attempts to develop international, national, regional, and local material resource efficiency and construction and demolition waste prevention and minimization programs. The chapter examines the concept of construction waste and definitions; assesses construction and demolition (CDW) waste quantification and source evaluation; and appraises current and emerging construction waste management and minimization approaches, tools, methodologies, and technologies.

2 CONCEPT AND DEFINITIONS Although the ideal of construction waste (CW) reduction is well acknowledged and generally accepted, it is proving difficult to implement. Traditionally, wastes have been viewed by construction stakeholders as inevitable by-products. As a result, managing on-site waste was often addressed within a legislative and health and safety context. Consequently, the perception that waste is unavoidable in construction activities disallows strategic considerations, engagement, and implementation attempts to manage construction waste at project level. There is anecdotal evidence that the overordering culture endemic across the construction sector is the result of on-site productivity issues. This has been attributed to the fact that the cost of materials excess is less than that of labor. On the

other hand, it has been widely argued that frequent design variations during the construction stage result in unsuitable or excess materials. Moving the construction industry toward a more sustainable future requires fundamental changes to current design, material procurement, and construction waste management. Emerging sustainable thinking is redefining the concept of waste from a “by-product” of processes to missed opportunities to cut costs and improve performance. Koskela [2] went further to argue that waste adds costs but does not add value. Similarly, Formoso et al. [3] classified waste as “unavoidable,” for which the costs to reduce it are higher than the economy produced, and “avoidable,” when the necessary investment to manage the produced waste is higher than the costs to prevent or reduce it. Therefore the concept of waste should be looked at in terms of activities that increase costs directly or indirectly but do not add value to the project. There is no generally accepted definition of waste. A common definition of waste was issued by the European Union (EU) Waste Framework Directive (WFD): “any substance or object which the holder discards or intends or is required to discard” [4]. This definition has been in use in its current wording for over three decades and applies to all waste irrespective of whether or not it is destined for disposal or recovery operations. The European Council made several revisions to the WFD, from its initial publication in 1975 to the latest amendments in October 2008 that came into force in March 2011. The revised WFD sets the basic concepts and definitions related to waste management, such as definitions of “waste,” “recycling,” and “recovery.” Significantly, the definition of “waste” has been clarified in the revised WFD through specific articles that formally introduce the concepts of “by-products” and “end-of-waste.” The introduction of a definition of by-products in WFD Article 5 formally recognizes the circumstances in which materials may fall outside the definition of waste. This change is intended to recognize that many

2. WASTE STREAMS (AND THEIR TREATMENT)

2 CONCEPT AND DEFINITIONS

“by-products” are reused before entering the waste stream. It describes when “waste” ceases to be “waste” and becomes a secondary raw material (so-called end-of-waste criteria) and how to distinguish between waste and by-products. The revised WFD places greater emphasis on waste prevention. As such, the waste hierarchy (prevention, preparing for reuse, recycling, recovery, and disposal) is placed at the heart of EU waste management policies (Fig. 19.1). The WFD enabled Member States (MS) in the EU to adopt their own national definitions of waste. For the scope of this chapter, the following definitions are adopted: • “Construction waste” (CW) is a material or product which needs “to be transported elsewhere from the construction site or used on the site itself other than the intended

FIG. 19.1

367

specific purpose of the project due to damage, excess or non- use or which cannot be used due to non- compliance with the specifications, or which is a by-product of the construction process” [5]. • “Design waste” is the waste arising from construction sites owing directly or indirectly to the design process [6]. • “Waste minimization” is the reduction of waste at source (i.e., designing out waste) by understanding its root causes and reengineering current processes and practices to alleviate its generation [6]. • “Waste management” is the process involved in dealing with waste once it has arisen, including site planning, transportation, storage, material handling, on-site operation, segregation, reuse and recycling, and final disposal [6].

The EU waste hierarchy.

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19. CURRENT AND EMERGING CONSTRUCTION WASTE MANAGEMENT STATUS, TRENDS AND APPROACHES

3 CONTEXT

the CDW generation versus GDP ratio is around 8.58 and 3.68Mt/GDP per capita in the EU and USA, respectively, and 27.78 CDW/GDP per capita in China. Within the EU, the bulk of CDW generation in 2014 is attributed to mineral wastes, excluding excavated soils and dredging spoils are not considered, the different waste categories generated for each MS in the EU. Fig. 19.3 shows CDW mineral waste streams in the EU, which include Mtonnes of CDW generation

The construction sector is the highest producer of waste if compared with other economic activities worldwide, accounting for 35% of the total waste generation in the European Union (EU) [7], which equates to four times more than the total household waste produced, and 30%–40% in China reaching one billion tons of CDW in 2013 [7, 8]. It is estimated that the construction and demolition activities generated in excess of 850 million tonnes of physical waste in the EU and over 530 million tons (Mt) in the United States in 2014 [9]. The amount of generated CDW has been routinely considered as an indicator for comparing waste management performance across different countries. However, CDW generation at a national level is influenced by several factors, namely, gross domestic product (GDP), population, and CDW-related regulatory measures. For example, Fig. 19.2 shows the relationship between CDW generation in 2014 and GDP per capita in USA, China, and the EU. Results indicate that CDW generation per GPD is significantly higher in China if compared with the EU and USA. Indeed,

1200 1000 800 600 400 200 0 0

50

100

200

150

GDP per capita USA

China

EU-28

FIG. 19.2 Amount of CDW generated considering the GDP per capita in 2014.

90% 80% 70% 60% 50% 40% 30%

Mineral waste from C&D Animal and vegetal wastes Wood wastes Paper and cardboard wastes Chemical wastes

Sweden

United Kingdom

Finland

Slovakia

Slovenia

Portugal

Romania

Poland

Austria

Malta

Netherlands

Hungary

Luxembourg

Latvia

Lithuania

Cyprus

Italy

Croatia

Spain

France

Ireland

Other mineral wastes (exc. Soils) Mixed ordinary wastes Textile wastes Rubber wastes Metals

Greece

Estonia

Denmark

Germany

Bulgaria

10% 0%

Czech Republic

20%

Belgium

% over the total generated

100%

Common sludges Waste containing PCB Plastic wastes Glass wastes

FIG. 19.3 Percentage of each waste stream generated in each Member State during 2014 (Data from Eurostat was used). 2. WASTE STREAMS (AND THEIR TREATMENT)

369

3 CONTEXT

concrete, bricks & ceramics, gypsum, wood, and asphalt. Similar CDW mineral categories were generated in the United States, including 65% of bulk aggregate (primarily concrete) and 14% of reclaimed asphalt pavement [10]. In terms of CDW reuse and recycling rates, China reused and recovered around 5% of CDW, while the EU and the USA reached higher recovery rates, around 79% and 70%, respectively. Despite two-third of MS in the EU have already reached the 70% CDW recovery target set in the EU Waste Framework Directive (WFD) by 2020, there are still other EU countries which need to take further measures to improve their recovery rates (Fig. 19.4). It is interesting to note that Ireland, Malta, and Czech Republic achieved the EU WFD recovery rate target, but only if backfilling is considered. Therefore backfilling will be a determinant factor for some MS to meet the 70% CDW recovery target by 2020. The significant differences on CDW management among the EU MS can be due to several reasons such as poor data sources and collection; no existence of national regulations dealing specifically with CDW; low landfill taxes or bans;

small number or inadequate distribution of recycling facilities; the cost of primary raw materials; and the lack of confidence in recycled materials, avoiding the existence of a market for secondary raw materials. Considering this situation, the European Commission is encouraging the uptake of the circular economy by boosting CDW recovery and management. The EU Action Plan for the Circular Economy [11] establishes general measures to be implemented throughout the whole cycle: from design, production, and consumption to waste management and the market for secondary raw materials. The CDW-related actions considered by the EU Action Plan for the Circular Economy aim to: • ensure improved recovery of valuable resources and adequate waste management in the construction and demolition sector, as well as facilitate assessing the environmental performance of buildings; • develop predemolition guidelines to boost high-value recycling in the sector as well as voluntary recycling protocols aimed to

100%

80%

EU target for 2020

70% 60% 50% 40% 30% 20%

Greece

Cyprus

Belgium

Romania

Malta

Ireland

Sweden

Slovakia

Spain

Czech Republic

France

Croatia

Hungary

Lithuania

Poland

Estonia

Latvia

Finland

Luxembourg

Austria

Germany

Denmark

United Kingdom

Italy

Bulgaria

Portugal

00%

Slovenia

10%

Netherlands

Recovery rate other than energy in %

90%

Recovery rate excluding backfilling Recovery rate including backfilling

FIG. 19.4 Recovery rates of mineral waste from construction and demolition in EU during 2014 (Data from Eurostat was used). 2. WASTE STREAMS (AND THEIR TREATMENT)

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19. CURRENT AND EMERGING CONSTRUCTION WASTE MANAGEMENT STATUS, TRENDS AND APPROACHES

4 CONSTRUCTION WASTE COMPOSITION AND QUANTIFICATION

improve quality of and build confidence in recycled construction materials; and • propose in the revised legislative proposal on waste to require better sorting of construction and demolition waste.

It is difficult to give exact figures of CW produced in a typical construction site, but previous research works estimated that 4%–30% of the total weight of building materials delivered to a building site becomes waste due to damage, loss, and overordering [13, 14]. The streams and composition of on-site wastes are highly variable, depending on the country and the construction techniques used. Table 19.1 summarizes the results from previous studies on CW quantification. CW can be broadly classified into three categories: waste which is: (1) not easily recycled or which present particular disposal issues, including chemicals (i.e., paint, solvents), asbestos and plaster; (2) not capable of being directly recycled in the construction industry, but may be recycled elsewhere, including timber, glass,

Some of these actions have already taken place. For instance, in 2016 the European Commission published the Construction and Demolition Waste Protocol aiming to increase confidence in CDW management and the trust in the quality of recycled building materials by means of improving waste identification, source separation and collection; improving waste logistics; improving waste processing; ensuring quality management; and developing an appropriate policy and framework [12]. In general, the above actions toward circular economy contribute to close the loop of construction product life cycles, helping to build a market for secondary materials and fostering sustainable economic growth in the construction industry.

TABLE 19.1

Percentage of Each Waste Category From the Total Generated [15–17]

Waste Stream

Spain

United Kingdom

Italy

Norway

Portugal

United States

India

China

Soil and rocks

–

–

–

–

–

–

35.00

–

Mixed concrete & ceramic waste

85.00

33.00

84.30

67.24

82.90

72.00

65.00

–

Concrete

–

–

85.13

–

70.00

35.00

8–35

Ceramic

–

–

10.48

–

2.00

30.00

15–50

Mixed waste

–

–

–

–

–

–

–

Wood

11.20

27.00

–

14.58

–

7.00

2.00

1–5

Paper

–

18.00

–

–

1.20

–

–

5–20

Plastic

0.20

–

–

0.16

–

–

Gypsum

–

10.00

–

–

6.40

3.00

–

–

Metals

1.80

3.00

0.08

3.63

4.50

1.00

5.00

1–8

Asphalt

–

–

6.90

–

4.20

14.00

2.00

–

Other

1.80

11.00

8.80

14.55

–

–

1.00

10–20

a

a

Corresponds to dry lining waste.

2. WASTE STREAMS (AND THEIR TREATMENT)

5 CONSTRUCTION WASTE SOURCE EVALUATION

paper, plastic, and oils; and (3) potentially valuable and easily reused or recycled, including inert waste such as concrete, stone masonry, bricks, tiles, asphalt, and soil. In terms of waste streams and weight, brick masonry and concrete present by far the largest potential for recycling in the building sector. This has been supported by the findings of comprehensive research conducted across the United States, the United Kingdom, Spain China, Brazil, Korea, and Hong Kong, which compared the streams and volumes of construction waste in these countries.

5 CONSTRUCTION WASTE SOURCE EVALUATION There are a variety of different approaches to the evaluation of the main origins, sources, and causes of CW. The extant of literature reveals a number of CW generation sources, which can be broadly categorized into 11 clusters. Table 19.2 presents that construction waste is generated throughout the project from inception

TABLE 19.2

371

to completion and the preconstruction stage has its considerable share. It has been estimated that 33% of wasted materials is due to architects failing to design out waste [18]. However, construction waste minimization through design is complex because buildings embody a large number of materials and processes. Equally, Osmani et al. [18] reported that “waste accepted as inevitable,” “poor defined responsibilities,” and “lack of training” are major challenges facing architects to design waste reduction measures in their projects. This is made more complex when further waste is created directly or indirectly by other projects’ stakeholders, namely, clients, contractors, subcontractors, and suppliers. Nonetheless, there is a general consensus that design changes during operation activities are one of the key origins of construction waste. The main drivers for design variations during construction are lack of understanding the underlying origins and causes, design changes to meet client’s changing requirements, complex designs, lack of communication between design and construction teams, lack of design information, unforeseen

Origins and Causes of Construction Waste [6]

Origins of Waste

Causes of Waste

Contractual

Waste client-driven/enforced Errors in contract documents Contract documents incomplete at commencement of construction

Procurement

Lack of early stakeholders’ involvement Poor communication and coordination among parties and trades Lack of allocated responsibility for decision making Incomplete or insufficient procurement documentation

Design

Design changes Design and detailing complexity Design and construction detail errors Inadequate/incoherent/incorrect specification Poor coordination and communication (late information, last minute client requirements, slow drawing revision and distribution) Continued

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19. CURRENT AND EMERGING CONSTRUCTION WASTE MANAGEMENT STATUS, TRENDS AND APPROACHES

TABLE 19.2

Origins and Causes of Construction Waste [6]—cont’d

Origins of Waste

Causes of Waste

On-site management and planning

Lack of on-site waste management plans Improper planning for required quantities Delays in passing information on types and sizes of materials and components to be used Lack of on-site material control Lack of supervision

Site operation

Accidents due to negligence Unused materials and products Equipment malfunction Poor craftsmanship Use of wrong materials resulting in their disposal Time pressure Poor work ethics

Transportation

Damage during transportation Difficulties for delivery vehicles accessing construction sites Insufficient protection during unloading Methods of unloading

Material ordering

Ordering errors (i.e., ordering items not in compliance with specification) Over allowances (i.e., difficulties to order small quantities) Shipping and suppliers’ errors

Material storage

Inappropriate site storage space leading to damage or deterioration Improper storing methods Materials stored far away from point of application

Material handling

Materials supplied in loose form On-site transportation methods from storage to the point of application Inadequate material handling

Residual

Waste from application processes (i.e., overpreparation of mortar) Off-cuts from cutting materials to length Waste from cutting uneconomical shapes Packaging

Other

Weather Vandalism Theft

ground conditions, and long project duration [19]. The main drivers for design variations during construction are: • last minute client requirements (resulting in rework); • designers’ inadequate experience in evaluating construction methods and the sequence of construction operation (leading to detailing errors that require alteration or demolition of completed works);

• increasing design complexity (producing offcuts); • lack of design information (leading to assumption offers by contractors and subcontractors, which result in overordering of materials); • unforeseen ground conditions (the risk of the uncertain nature of ground conditions is often accepted that waste may occur on modifying the design as required rather than

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373

6 CONSTRUCTION WASTE MANAGEMENT AND MINIMIZATION APPROACHES

undertaking expensive preliminary investigations to confirm the conditions resulting in soil waste); and • long project durations (allowing the design to be modified to suit changes in the market, research, or legislation). Construction procurement systems-related waste sources fall under four main themes: uncoordinated early involvement of project stakeholders, ineffective project communication and coordination, unclear allocation of responsibilities, and inconsistent procurement documentation [20].

6 CONSTRUCTION WASTE MANAGEMENT AND MINIMIZATION APPROACHES Despite international governmental, industrial, and academic efforts to develop waste reduction thinking in construction, uptake globally is piecemeal. That said, an ever-increasing global research has been devoted to figure out how to curb construction waste generation.

As presented in Table 19.3, the current and ongoing research in the field of CW management and minimization can be broadly categorized into 19 clusters. The bulk of CW research is largely guided by the “3 Rs” principle of waste (reduction, reuse, and recycling), otherwise known as the waste hierarchy. Earlier research reports, such as the studies aimed at promoting awareness in the construction industry about the benefits of waste minimization, including cost savings. The impact of legislation on on-site waste management practices resulted in a number of research studies. Furthermore, research studies were conducted to investigate attitudinal, behavioral, and incentivized approaches to improving on-site waste management. Tools, models, and techniques have been developed to handle and better manage on-site construction waste segregation, quantify waste generation, estimate waste generation rates, audit waste, reuse waste, and collate and analyze on-site waste streams. Furthermore, different approaches to waste source evaluation were

TABLE 19.3

Current and Ongoing Research in the Field of Construction Waste Management and Minimization

Phase

CW Management Approach

Employed Method

General

1

Impact of legislation on waste management practices

Literature review; content analysis; questionnaires; interviews; case studies

2

BIM aided CW management

Questionnaires; interviews

3

CW minimization benefits

Literature review; system dynamics; questionnaires; interviews; case studies

4

Forecasting tools

Literature review; case studies

5

CW quantification and composition

Literature review; observations; statistical models; questionnaires; interviews; case studies; archival analysis; mass balance principles

6

CW source evaluation

Literature review; questionnaires; interviews

7

Procurement waste minimization

Literature review; questionnaires; interviews

8

Design waste minimization

Literature review; questionnaires; interviews; system dynamics

Design

Continued

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19. CURRENT AND EMERGING CONSTRUCTION WASTE MANAGEMENT STATUS, TRENDS AND APPROACHES

TABLE 19.3 cont’d

Current and Ongoing Research in the Field of Construction Waste Management and Minimization—

Phase

CW Management Approach

Employed Method

Construction

9

Literature review; workshops; observations; questionnaires; interviews; case studies

End-of-life

Waste reduction potential through modern methods of construction and off-site construction

10 On-site CW sorting methods and techniques

Literature review; observations; questionnaires; interviews; case studies

11 CW flow modeling

Literature review; Life Cycle Analysis (LCA); Material Flow Analysis (MFA); system dynamics; questionnaires; interviews; case studies

12 On-site waste auditing and assessment tools

Literature review; software packages and online protocols

13 On-site waste management practice improvements

Literature review; Life Cycle Analysis (LCA); system dynamics; questionnaires; interviews; case studies

14 CW minimization standards and guides

Literature review; focus groups; workshops

15 Attitudes toward CW minimization

Literature review; questionnaires; interviews

16 Comparative waste management studies

Literature review; system dynamics; questionnaires; interviews; case studies; Big Data Analysis

17 Recycling and recovery technologies

Literature review; case studies

18 CW reuse, recycling and recovery

Literature review; observations; laboratory experiments

19 Postnatural disaster waste management

Literature review; case studies

developed to identify construction and design waste causes. Additionally, an increased number of studies were conducted to assess the potential impact of Modern Methods of Construction (MMC) and off-site construction techniques on waste reduction. Emerging information technologies, bar coding systems, GPS, GIS, and wide area networks (WANs) are being progressively introduced into construction waste research. At the end of the waste management research spectrum, various waste recycling “soft” decision making and marketing methodologies and “hard” laboratory technologies and resulting improved waste have been developed as a last attempt to divert construction waste from landfill. While these methods facilitate waste auditing, assessment, reuse, and recycling; they were developed to manage waste that has already been produced. As such, there is

insufficient effort and no structured approach to address waste at source and specifically design waste. That said, it is widely argued that future waste efforts should focus on designing out waste [19]. The last few years witnessed an increasing, yet, limited design waste-related research studies, including Building Information Modeling (BIM) aided waste minimization [21].

7 CONSTRUCTION WASTE MINIMIZATION AND MANAGEMENT TOOLS, METHODOLOGIES, AND TECHNOLOGIES Several construction waste management tools, methods, and technologies are being used in the construction industry to (1) forecast and

2. WASTE STREAMS (AND THEIR TREATMENT)

7 CONSTRUCTION WASTE MINIMIZATION AND MANAGEMENT TOOLS, METHODOLOGIES, AND TECHNOLOGIES

design out waste; (2) manage on-site waste; and (3) recycle and recover end-of-life materials and products during preconstruction, construction, and demolition stages, respectively.

7.1 Preconstruction Stage: Forecasting and Designing Out Waste At present, there are insufficient design decisions supporting tools to integrate designing out waste strategies in construction projects. However, the last few years witnessed an increasing; yet, limited design waste-related research. Indeed, social CW awareness together with the increasing waste legislation and fiscal measures developed has led to the development of an ever-increasing number of templates, guides, manuals [22] and Standards (BS 8895: Designing for material efficiency in building projects) to support designers to embed waste minimization in their projects. In particular, Waste Management Plan templates provide automated templates to facilitate the development of waste management plans and thus calculate variables of interest such as waste output and costs. Furthermore, WRAP [22] introduced a guide containing broad guidance for architects to adopt a fivefold waste minimization strategy in their projects. The guide comprises the following five principles: design for reuse and recovery, design for off-site construction, design for material optimization, design for waste-efficient procurement, and design for deconstruction and flexibility. Although the content of WRAP designing out waste guide is a step forward to engage architects in designing out waste, the guide did not associate the proposed principles with all parameters of the design process environment, including stakeholders’ coordination, communication, and roles. More importantly, the guide failed to conduct a waste diagnosis across all design stages to map out the direct and indirect design waste origins, causes and sources that are

375

critical in informing and implementing designing out waste principles and strategies. Waste prediction tools estimate potential CW generation in building projects. In general, these tools are based on aggregating waste indices or ratios which are obtained by dividing the amount of CW generated (in volume or weight) by either the amount of materials purchased or per the gross floor area of the project (m2). For this, reliable ratios for CW estimation are essential in order to plan an efficient waste management system for a construction site or a region. Methods, which were developed to estimate CW generation, vary depending on the scope of CW estimation: regional level or construction project. Studies at a regional level estimate the CW generation within an area by multiplying the construction activity by the waste generation rate determined at a project level. Most of these studies have sourced data from government statistics to estimate the construction activity of a region. Therefore data sources play a significant role in these studies as they are directly related with the accuracy of the estimations. Furthermore, case studies are usually adopted to gain knowledge on CW generation and composition. Researchers have used different techniques for data collection such as field observations, sorting and weighing on site, truckload records and surveys. Several studies analyzed CW generation rate according to several factors: building use, structural typologies, dwellings’ size, or a combination of them; while others analyzed the accumulation rate of construction waste throughout the whole project duration [23]. For example, performance indicators for individual CW products have been produced from completed projects on SMARTWaste Plan. These performance indicators have been applied to construction output to provide an estimate of waste arising by product from new build construction and refurbishment and determine on-site waste management methods and actions for each waste type. Similarly, WRAP developed Net Waste Tool to help generating waste forecasts

2. WASTE STREAMS (AND THEIR TREATMENT)

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19. CURRENT AND EMERGING CONSTRUCTION WASTE MANAGEMENT STATUS, TRENDS AND APPROACHES

during site operations and prioritizing waste reduction and recovery actions to input into a Site Waste Management Plan. However, a number of recent studies used a multiple linear regression analysis, proposed a statistical model to determine the amount of waste generated by assessing the influence of design process and production system [24]. These culminated in the generation to a set of design variables related to compactness of the building, the practice of waste recycling in the construction site, the floor plan area, and the adopted construction system. That said, the latter was restricted to a very limited number of broad design variables that are specific to high-rise buildings. As such, it did not offer a comprehensive model to assess the impact of all design processes on on-site waste production for any type of building projects. In the last few years, a limited literature suggests that Building Information Modeling (BIM) has the potential to drive out construction waste in building. It has been argued that BIM techniques can be used by architects as a platform to minimize design waste in their projects; structural engineers to reduce construction generation for structural reinforcement and demolition contractors to optimize reuse, recycling, and recovery during demolition and renovation activities. However, methods and tools that integrate informed designing out waste strategies across all project stages are absent in the literature.

7.2 Construction Stage: On-Site Construction Waste Management The main contractors are considering environmental issues, not being limited to the current legislation, and seeking the implementation of sustainable CW management practices. Increasingly, construction companies are aware of the impact of building activities on the natural environment on the one hand, and Corporate Social Responsibility on the other. As such, they

introduced several CW management practices, including development of a site waste management plan for each project, on-site CW management training packages for their workers and subcontractors, and innovative processes aimed at minimizing waste and selecting recycled and recyclable materials. However, despite large construction companies’ endeavors to reduce and better manage CW, the vast majority of small and medium enterprises in the construction industry engage significantly less in the process and their approach is predominantly reactive to legislative requirements. Several construction waste management tools, such as site waste management plans, toolbox talks, and material bar-code systems, are being used during the construction stage. On-site waste management tools have been developed to handle and better manage on-site construction waste segregation; quantify waste generation; estimate waste generation rates; waste data analysis; audit construction waste; reuse on-site waste and collate and analyze on-site waste streams. In particular, CW estimation and quantification tools are used to calculate the quantity of waste generated from building projects. Data collection and audit tools record the amount, type, and sources of waste generated in a building project. For example, CALIBRE and ConstructClear are tools which allow project management teams to refine on-site processes, by recording real time data on site to measure on-site efficiency and quantifying CW. SmartStart in the United Kingdom and WasteSpec in the United States are tools to facilitate on-site auditing and thus evaluate the waste management performed across all the construction sites of a company. Furthermore, an increased number of studies were conducted to assess the potential impact of off-site construction techniques on on-site waste reduction. Emerging information technologies, bar coding systems, GPS, GIS, and wide area networks (WANs) are being progressively introduced to effectively manage on-site waste.

2. WASTE STREAMS (AND THEIR TREATMENT)

8 CONSTRUCTION WASTE MANAGEMENT CHALLENGES AND INCENTIVES

7.3 End-of-Life Waste Recovery, Recycling, and Circularity In the last few years, location-based tools, which are usually GIS enabled, have been developed to provide the location of CW management services. For example, BREMap developed a searchable map to find the nearest facility for CW recycling facilities. The quality of CW is directly influenced by the performance carried out in the construction and/or demolition site. For instance, one of the main difficulties for waste recovery is the collection of mixed waste (instead of on-site sorting) and the inefficient mechanical sorting of the mixed waste. Therefore the workers’ attitude and training regarding CW management is essential for enhancing CW sorting and also

FIG. 19.5

377

more efficient waste sorting technologies are needed to generate cleaner CW for recovery. By and large, technologies used for waste recovery, recycling, and circularity encompasses three interrelated methods: source collection and separation, processing, and recovery and treatment. Fig. 19.5 shows a summary of the different technologies for CW recovery used in each stage of the process.

8 CONSTRUCTION WASTE MANAGEMENT CHALLENGES AND INCENTIVES Despite the evidence to support the economic and business benefits of waste reduction, the construction industry has been slow to reform

CW recycling and recovery technologies.

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its practices. The literature identified a variety of constraining factors that impede the construction industry to adopt a sustainable waste minimization approach. These are largely due to the conservative aspect of the industry. It is widely established in the literature that the major construction waste minimization constraints are related to perceptions and attitudes toward waste management. The main challenges facing project stakeholders to adopt effective waste reduction strategies in their projects are: • Lack of managerial commitment. • Lack of industry construction waste minimization norms. • Difficulties in changing existing practices. • Lack of operatives experience in waste management. • Perception that waste management systems are not cost effective. • Waste accepted as inevitable by-product of construction. • Unwillingness to reuse or recycle materials with little economic value. • Extra costs to implement CW-related strategies and initiatives. • Any savings made are unequally distributed, therefore giving little incentive for workers to participate in waste management. • Poorly defined individual responsibilities for waste management. • Limited waste minimization guidance. • Time consuming devoted to sorting out and handling on-site waste, thus extending the work plan schedule. • An increase of red tape can be found due to extra paperwork for filling control forms, inspection reports, and so on. On the other hand, “financial rewards” and “legislation” seem to be the main incentives that could drive waste minimization in the construction industry. Although there is a consensus that legislation can be effective in maintaining the pressure in improving waste minimization, it was suggested that financial drivers at project level will have a far-reaching

impact on waste reduction practices. Waste minimization financial benefits are related to the direct costs of both waste disposal and raw material purchase. However, the true cost of waste is estimated to be around 20 times the disposal of waste. A study by a major UK contracting company revealed that that a typical construction skip costs around £1343. This figure is broken into £85 for skip hire (6.4% of cost), £163 for labor (12.1% of cost), and £1095 of cost of wasted materials (81.5% of cost). Therefore the financial cost of waste for a generic house (five skips) is around £6715, of which £5439 is attributed to the cost of discarded materials.

9 DISCUSSION AND CONCLUSIONS The current thinking of waste minimization practices is heavily focused on the physical minimization of construction waste and identification of site waste streams. Tools, models, and techniques have been developed to help handle and better manage on-site waste generation. Although these tools facilitate auditing, assessment, and benchmarking, their waste source evaluation approach is curtailed and piecemeal, as it fails to effectively address the causative issues of waste production throughout all stages of a construction project. The challenge now is to provide a novel platform for the next generation of tools and techniques that will identify and resolve the fundamental causes and origins of construction waste. The basis for such an approach could utilize Building Information Modeling (BIM) and related technologies, in particular Virtual Prototyping, to provide a platform for “virtual” waste evaluation which reviews and assesses the severity of waste generation throughout all stages of the construction project life cycle. Although BIM design methods are not currently as fully utilized in the construction industry as in other industries, there is general recognition that BIM adoption will become more

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REFERENCES

pronounced to demonstrate not only the entire building life cycle but also assess and evaluate the environmental performance and impacts of buildings. Construction waste minimization can be viewed as a threat requiring ever-increasing expenditure on end-of-pipe recycling tools and technologies to meet ever-increasing legislation, or as an opportunity to cut costs and improve performance. The choice should be obvious, but there is a need for a culture change. Rethinking waste management in construction requires adopting “cyclic” rather than “linear” approach to design and construction. This requires reengineering current practice to contribute to a cleaner environment through efficient and cost-effective sustainable waste minimization strategies. However, for waste minimization to be effective and self-sustaining, it is important that all stakeholders along the construction supply chain embrace a more proactive approach in dealing with waste. In recognition of the responsibility of the architectural profession, through its leading role in project management and a key player in the construction industry, architects should move beyond the concept of “eco-efficiency” through bolt-on environmental strategies and strive to adopt “eco-effective” practices by implementing a holistic approach to design out waste, which will be reinforced in tender documents and implemented during the construction stage, in addition to the capture and dissemination of lessons learnt to inform construction waste reduction baselines and benchmarking in future projects. Achieving “zero waste” will be a breakthrough strategy for a world in an environmental crisis; however, this is a highly challenging target in construction, but involving and committing all stakeholders to reduce waste at source and developing efficient waste management strategies by reusing and recycling materials and components can take the industry closer to the “zero waste” vision, hence, moving from myth to reality.

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