Tesis - Diseño Sostenble de Una Carretera- Metodo Leed

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Sustainable Roadway Design-A Model For An Environmental Rating System

Martina Soderlund

A thesis submitted in partial fulfillment of the requirements for the degree of

Master of Science in Civil Engineering

University of Washington

2007

Program Authorized to Offer Degree:Civil and Environmental Engineering


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University of Washington

Abstract

Sustainable Roadway Design –A Model For An Environmental Rating System

Martina Soderlund

Chair of the Supervisory Committee:Assistant Professor Stephen T. MuenchCivil and Environmental Engineering

The building construction industry in the U.S. has in the last 5-10 years gone through a market

transformation towards construction and design of more sustainable buildings. One reason to thistransformation is the implementation of the LEEDTM (Leadership for Energy and Environmental

Design) green building environmental rating system.

The construction of roads is one of the most material demanding industries in the world with

great economic as well as environmental impacts. Significant efforts are seen in terms of

recycling and reuse of pavement materials. These efforts are strong and are beginning to be part

of industry processes and practice, however, this is not sufficient to create sustainable products

over entire life cycles.

If a similar rating system such as LEEDTM could gain popularity for projects in the roadway

construction industry as it has in the building industry, significant benefits in environmental

awareness and sustainability in design can be achieved. Today no such rating system exists for

roads.

This study has developed a model for such a system for use in Washington State. Elements and


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TABLE OF CONTENTS

List of Figures..................................................................................................................................v

List of Tables ..................................................................................................................................vi

1. Introduction ............................................................................................................................... 1

2. Research Objective....................................................................................................................2

2.1 Goal and Scope ...................................................................................................... 2

3. Methodology ............................................................................................................................. 3

3.1 Literature review....................................................................................................3 3.2 Classification of design categories.........................................................................3 3.3 Development of a rating system ............................................................................ 3

4. Background ............................................................................................................................... 4

4.1 U.S. Road Statistics ............................................................................................... 4

5. Environmental Rating Systems ................................................................................................. 6

5.1 LEED for Buildings...............................................................................................6 5.1.1 LEED Categories And Credits .............................................................. 6 5.1.2 LEED And Sustainability...................................................................... 7

6. An Environmental Rating System For Roadways.....................................................................9

6.1 System Categories – A Summary .......................................................................... 9

7. The Categories In Detail..........................................................................................................10

8. Materials & Resources (MR) .................................................................................................. 11

8.1 Overview..............................................................................................................11 8.1.1 Terminology ........................................................................................12

8.2 Waste, Recycling & Road Construction.............................................................. 13 8.2.1 Construction Waste and Recycling......................................................14 8.2.2 Construction Debris in Washington State ........................................... 16

8.3 Design Options .................................................................................................... 17 8.3.1 Reclaimed Asphalt Pavements ............................................................ 19 8.3.2 Recycled Concrete Pavements.............................................................20 8.3.3 Steel ..................................................................................................... 21 8.3.4 Blast Furnace slag, Slag cement..........................................................21 8.3.5 Fly-Ash................................................................................................22 8.3.6 Glass .................................................................................................... 24 8.3.7 Scrap Tires...........................................................................................24 8.3.8 Shingles ...............................................................................................25


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8.9 Criteria Definitions .............................................................................................. 33 8.9.1

MR-1. Construction Waste Management ............................................ 34

8.9.2 MR-2. Material Reuse 1 ...................................................................... 36 8.9.3 MR-3. Material Reuse 2 ...................................................................... 37 8.9.4 MR-4. Recycled Content 1 .................................................................. 38 8.9.5 MR-5. Recycled content 2...................................................................39 8.9.6 MR-6. Life Cycle Analysis..................................................................40 8.9.7 MR-7. Regionally Provided Material .................................................. 41

8.10 Discussion............................................................................................................42

9. Stormwater Management (SM) ............................................................................................... 43

9.1 Overview..............................................................................................................43 9.2 Stormwater and Roadways .................................................................................. 45

9.2.1 Best Management Practices, BMP’s ................................................... 46 9.3 BMP Options ....................................................................................................... 47

9.3.1 BMPs for Stormwater Source Control.................................................47 9.3.2 BMPs for Stormwater Runoff Treatment ............................................ 47 9.3.3 BMPs for Stormwater Flow Control ................................................... 48 9.3.4 Emerging Techniques..........................................................................49 9.3.5 Low Impact Development Design (LID).............................................50 9.3.6 Manufactured Devices – Subsurface Treatments ................................ 52 9.3.7 Partial Exfiltration Trench (PET) ........................................................54 9.3.8 Permeable Pavements..........................................................................54 9.3.9 Alternative Road Layout for Residential Areas...................................58

9.4 Pollution Prevention Opportunities ..................................................................... 59 9.5 Regulations in Washington State.........................................................................63 9.6 Criteria Definitions .............................................................................................. 65

9.6.1 SM-1. Storm Water Management........................................................66 9.6.2 SM-2. Storm Water Design 1 - Runoff Treatment .............................. 68 9.6.3 SM-3. Storm Water Design 2 – Permeable Area.................................69 9.6.4 SM-4. Storm Water Design 3 – Permeable Pavement.........................71 9.6.5 SM-5. Innovative Stormwater Technology ......................................... 72

10. Energy & Environmental Control (ECC) ................................................................................ 73

10.1 Light Pollution..................................................................................................... 73 10.2 Eco-Viaducts........................................................................................................74 10.3 Visual Quality (Landscape & Architecture) ........................................................ 75 10.4 Pedestrian/Bicycle Access ................................................................................... 75 10.5 Cool Pavements & the Heat Island Effect ........................................................... 76

10.5.1 Overview .............................................................................................76 10.5.2 Impacts ................................................................................................77 10.5.3 Cool Pavements...................................................................................78


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10.6.4 Design Options .................................................................................... 89 10.6.5 Pollution Prevention Opportunities ..................................................... 91

10.7 Regulations in Washington State.........................................................................92 10.7.1 Cool Pavements...................................................................................92 10.7.2 Quieter Pavements...............................................................................93

10.8 Criteria Definitions .............................................................................................. 94 10.8.1 EEC-1. Cool Pavements ...................................................................... 95 10.8.2 EEC-2. Quieter Pavements..................................................................96

10.9 Discussion............................................................................................................97

11. Construction Activities (CA)...................................................................................................98

11.1 Overview..............................................................................................................98 11.2 Pavement Construction Impacts .......................................................................... 98

11.2.1 Air Pollution........................................................................................ 98 11.2.2 Water Pollution..................................................................................102 11.2.3 Noise Pollution.................................................................................. 103 11.2.4 Energy Consumption.........................................................................104

11.3 Pavement Construction Activities ..................................................................... 106 11.3.1 Rigid Pavements................................................................................107 11.3.2 Flexible Pavements............................................................................109

11.4 Pollution Prevention Opportunities ................................................................... 110 11.4.1 Reduce Emissions From Dust Control .............................................. 110 11.4.2 Reduce Emissions From Diesel Vehicles..........................................110 11.4.3 Reduce Fossil Fuel Dependency........................................................114 11.4.4 Mitigate Construction Noise..............................................................114 11.4.5 Temporary Stormwater Control.........................................................115 11.4.6 Emissions from HMA Paving............................................................116

11.5 Regulations in Washington State.......................................................................118 11.5.1 Emissions...........................................................................................118 11.5.2 Stormwater ........................................................................................119 11.5.3 Noise.................................................................................................. 119 11.5.4 Energy ...............................................................................................120

11.6 Credit Definitions .............................................................................................. 121 11.6.1 CA-1. Reduce Non-road Diesel Engines and Fuel Emissions...........122 11.6.2 CA-2. Reduce Fossil Fuel Dependency.............................................123 11.6.3 CA-3. Temporary Stormwater Control..............................................124 11.6.4 CA-4. Noise Mitigation Planning......................................................125 11.6.5 CA-5. Reduce Paving Emissions 1....................................................126 11.6.6 CA-6. Reduce Paving Emissions 2....................................................127

12. Innovation & Design (ID) ..................................................................................................... 128

12.1 Credit Definition................................................................................................128


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14.1.3 Reasons for LEED’s Breakthrough ................................................... 134 14.2 LEED From An Organizational Standpoint.......................................................135

14.2.1 The Development of LEED...............................................................136 14.2.2 Implementation Strategies of LEED..................................................137

14.3 Development And Implementation Of A Rating System For Roadways .......... 138 14.4 Discussion.......................................................................................................... 141

15. Conclusions And Recommendations.....................................................................................143

15.1 Conclusions........................................................................................................143 15.2 Recommendations.............................................................................................. 145

List Of References ....................................................................................................................... 146

Appendix A: Design Option Evaluation For Recycled Materials............................................... 159

Appendix B: Analysis Of Reuse And Recycled Content............................................................ 161

Appendix C: Design Option Evaluation For Cool Pavement Applications................................ 169

Appendix D: Interview Questions .............................................................................................. 171

Appendix E: Location Overview Of Aggregate Sources In WA (WSDOT) .............................. 175


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LIST OF FIGURES

Figure Number Page

Figure 1. Cross section and alignment view of a roadway. ............................................................. 4 Figure 2. The Highway environment ............................................................................................. 14 Figure 3. Production and consumption by market sector...............................................................15 Figure 4. Asphalt and Concrete Recycled in Washington State .................................................... 16 Figure 5. Stockpiled RAP .............................................................................................................. 19 Figure 6. Slag cement .................................................................................................................... 22 Figure 7. Effect on embodied greenhouse gas reduction in concrete ............................................ 27

Figure 8. Effect on embodied energy reduction in concrete.......................................................... 27 Figure 9. Effect on embodied virgin materials extraction in concrete...........................................28 Figure 10. Infiltration and runoff rates in relation to imperviousness ........................................... 44 Figure 11. Illustration of a typical bioretention system ................................................................. 51 Figure 12. Example of bioretention system landscaping ............................................................... 52 Figure 13. Underground detention units ........................................................................................ 52Figure 14 Illustration of Aqua Swirl and Filter treatment system ................................................ 54Figure 15. Cross section of a PET. ................................................................................................54

Figure 16. Typical porous asphalt pavement structure .................................................................. 55 Figure 17. Porous asphalt in Arizona and skid resistance..............................................................56 Figure 18. Porous asphalt water penetration (right).......................................................................57 Figure 19. Road layout options and impervious area.....................................................................58 Figure 20. Eco-Viaduct constructed in Croatia, Europe. ............................................................... 74 Figure 21. Illustration of an urban heat island over a city ............................................................. 76 Figure 22. Illustration of the interrelationship of heat transfer in a pavement structure................ 79 Figure 23. Surface temperature and albedo for selected types of pavements in Phoenix, 2004.... 81 Figure 24. Sound levels related to vehicle speed for noise generated from vehicles..................... 88

Figure 25. Noise reduction of double-layered porous asphalt in Copenhagen over 5 years.......... 90 Figure 26. Noise-wall installation in Washington State ................................................................ 92 Figure 27. Fugitive dust from construction....................................................................................99 Figure 28. Sources of diesel PM-2.5 in Washington State in 2002 ............................................. 101 Figure 29. Emissions and fumes from paving..............................................................................102 Figure 30. Polluted stormwater on a construction site.................................................................103 Figure 31. Various construction equipment and activities on a project site ................................ 105 Figure 32. Trucks waiting in line.................................................................................................106

Figure 33. HMA paving in WA ................................................................................................... 116Figure 34 WMA paving in WA .................................................................................................. 118Figure 35. HMA leaving the plant ............................................................................................... 117Figure 36 WMA leaving the plant ..............................................................................................119Figure 37. The intended market position of LEED......................................................................132 Figure 38. Overview of the LEED development organization .................................................... 136 Figure 39 Market relationships 137


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LIST OF TABLES

Table Number Page

Table 1. Summary of System Categories and their intent................................................................9 Table 2. Waste or by-products to be used by application .............................................................. 18 Table 3. Credits available in category Materials & Resources ...................................................... 33 Table 4. Stormwater runoff treatment BMPs.................................................................................48 Table 5, Stormwater flow control BMPs ....................................................................................... 49 Table 6. LID practices and their hydrologic functions .................................................................. 50 Table 7. LID practices and their pollutant removal efficiencies....................................................51

Table 8. Overview of effective life for BMPs ............................................................................... 60 Table 9. Summary of stormwater strategies and related footprints ............................................... 61 Table 10. Runoff treatment targets and applications for roadway projects ................................... 64 Table 11. Credits available in category Stormwater Management ................................................ 65 Table 12. Land cover percentages in four urban areas...................................................................77 Table 13. Percentage of pavement area by type of use..................................................................77 Table 14. Comparisons of albedo for new and weathered pavement top-layers............................ 80 Table 15. Credits available in category Energy & Environmental Control ................................... 94

Table 16. Rigid pavement construction activities........................................................................108 Table 17. Flexible pavement construction activities....................................................................109 Table 18. Available options for emission control and related reduced air emissions.................. 111 Table 19. Warm mix asphalt technology summary ..................................................................... 117 Table 20. EPA non-road diesel standard......................................................................................118 Table 21. Credits available in category Construction Activities..................................................121 Table 22. Final system model: A summary of categories and credits available.......................... 143 Table 23. Certification credit requirements ................................................................................. 144


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ACKNOWLEDGEMENTS

I would like to give special thanks to Professor Stephen T. Muench for outstanding support andenthusiastic guidance throughout my work as well as to fellow committee members Joe P.Mahoney and G. Scott Rutherford for their commitment and support. I deeply appreciate thecorporate professionals that took time to meet with me for interviews and helpful discussions.Finally I also want to thank the Valle Scholarship and Scandinavian Exchange Program forgenerous funding throughout my graduate work at the University of Washington.


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1. INTRODUCTIONAs the outcome of the last 150 years of industry development and its impact on our environment

starts to become more evident, the awareness of environmental impacts due to design become

more and more important. The construction industry has one of the highest impacts on the

environment in regards to energy use, material use and waste products. Within the construction

industry, infrastructure construction or roadway design is one of the largest economic and also

material consuming industries in the U.S. Extensive programs for recycling and reuse of materials

have been developed to take care of waste and end-of-life products. While these efforts are strong

and have become part of industry practice, this is not sufficient to create sustainable products over

entire life cycles. All engineers, designers, decision makers and others involved in any design and

construction process make decisions which have impact on the environment. These decisions

need to be taken with a higher environmental awareness already in the design process.

A number of different tools used to help facilitate these decisions towards more sustainable

alternatives are available today. One tool that has rapidly gained popularity in the U.S. is the

LEEDTM (Leadership in Energy and Environmental Design) green building environmental rating

system developed by the U.S. Green Building Council (USGBC). What the system provides is a

common language in the building industry for the incorporation of more sustainable elements in a project, and it is shown to provide an overall awareness of environmental impacts.

If a similar rating system could gain popularity for projects in the roadway industry as it has in

the building industry, this would provide a means for performance based improvements in terms

of environmental impacts. This would increase the awareness of environmental matters in part of

an industry with the highest impact on our environment and it would, as LEED has in the building

industry, cause a strong movement effect with new markets emerging providing more

environmentally sound solutions.


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2. RESEARCH OBJECTIVEThis Master’s thesis will look into the possibility of how an environmental rating system for

roads could be structured to impact and improve sustainability measures in roadway design. The

intent is to develop a framework for such a system for Washington State and research how the

categories and credits could be put together. This include:

• Define, classify and characterize elements in a roadway construction project and

their environmental impacts and importance.

• Identify design decisions with high environmental impacts and define categories

for credit ratings.

• Compare the strategy of the LEED program and benchmark divisions for credits

and documentations required to earn credits.

• Put together a model for an environmental rating system for roadway design and

define some of the criteria’s.

• Discuss implementation strategy and impacts.

2.1 GOAL AND SCOPE

Goal:The goal for the thesis is to set up a framework for an environmental rating system for

roadway design. The overall goal is to encourage an increased demand for more environmentally

sound solutions and provide common metrics in the roadway construction industry of important

environmental impacts and their relation to different technology systems.

Scope:The framework in this thesis will present all categories that eventually should be

researched and included in a rating system, however, only some of these categories will be

analyzed in more detail and presented with actual credit requirements. The scope of the system

presented in this thesis will relate to the design and construction of the roadway structure itself

(the pavement) and will not include the activities taking place using the road (traffic impacts) or

the impact on the surrounding environment due to urban design (alignment). These impacts will


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3.

METHODOLOGY

3.1 LITERATURE REVIEW

The literature review worked as a base in the research to find information to identify the

categories suggested for the environmental rating system.

The literature review provided data and information for classification and characterization of the

categories to be defined. This review looked into current trends in the road construction industry

in terms of new and older technologies promoting sustainability and environmental design. This

review also studied current regulations and legislatures for environmental design that needs to be

addressed in a project. There are Federal requirements, State requirements, Local ordinances and

other agency requirements and regulations to be considered. No rating system can be developed

without taking these regulations into consideration.

3.2 CLASSIFICATION OF DESIGN CATEGORIES

This effort defined broad processes involved in a roadway project. Design options and

technologies were identified and compared. The LEED program was studied carefully in order to

assist in determining credits applicable in roadway design and construction. Interviews were held

with professionals in the construction industry and other state or federal organizations to learn

about the impacts and implementation of LEED. Interviews with contractors/designers working

with LEED today helped identify advantages and disadvantages with the current LEED system.

3.3 DEVELOPMENT OF A RATING SYSTEM

The last part of the project was to develop a framework for an environmental rating system for

roadway design and construction using the characterization and classification information as a

base. Pollution prevention opportunities were identified for each category and discussed.

Categories were given different amounts of credits based on these pollution prevention

opportunities, and these credits were analyzed for requirements and feasible limits to be reached.


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4. BACKGROUND

When using the LEED system as a model for this thesis, it is important to remember that the

difference between a roadway and a building is significant. A building is a point source impact

with complicated mechanical systems within the boundaries of the building, such as the walls.

The environment of concern is to a large extent the indoor environment and the closest

surroundings outside the building.

A roadway is a point source impact in the cross-section of the road, but in addition to this also a

linear impact where the impact runs through the landscape; urban areas, rural areas, different

geographic regions with a variety of bio-regions with different sensitivities and properties. This

makes the impacts from a road more complex and far-reaching compared to a building.

Figure 1. Cross section and alignment view of a roadway.

(Modified from www.infovisual.info)

4.1 U.S. ROAD STATISTICS There are almost 4 million miles (6.5 million km) of roads in the U.S (USGS, 2006), including

urban and rural public roads. In Washington State there are a total of 83,000 miles of urban and

public roads (FHWA, 2005). Roads have a huge impact of the surrounding environment in terms

f t i l t ti ti iti d i lif i t ( ) i t ti d

Surface Course

Base Course

Subbase

Subgrade

Median strip

Shoulder


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be used in roadway construction (Carpenter et al, 2006). In addition to this large quantities of

steel, water, cement and bituminous products are being used as well. The manufacture and

extraction of these materials is not only depleting natural resources; all activities related to

managing the material such as extraction processes, production of new construction materials and

all activities needed for transport are also significant.

Most road construction taking place today is rehabilitation or repairs of existing roads. A majority

of the public paved roads in the U.S. are paved asphalt roads (about 93 %). In Washington State

about 87 % of paved roads are surfaced with asphalt materials and about 13 % with Portland

Cement Concrete (PGI, 2003). Rehabilitation and maintenance of these roads has to take place

regularly depending on pavement type. As one example most of the PCC sections of the interstate

highways in Washington State are reaching or have already reached the end of its design life.

This means large quantities of waste products will be generated (such as PCC and steel) and largequantities of virgin materials will be required to replace them.

Approximately 4.1 billion metric tons of non-hazardous solid waste materials are generated

annually in the U.S. (AASHTO; 2005). When recycling of material and reuse of some of these

quantities have several potential uses in the roadway environment (Eighmy; 2001) there are also

other measures to define if a road could be called “green” or not. Some of these measures will be

described in this report.


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5. ENVIRONMENTAL RATING SYSTEMSThere are a vast number of environmental rating systems, sometimes called eco-labeling systems,

on the market for a big variety of products. These systems are developed to help the consumer

choose more sustainable products. The U.S. Environmental Protection Agency’s (EPA) Energy

Star is one well known example promoting energy efficient products for homes. In the

construction industry the one most well known is LEEDTM (Leadership in Energy and

Environmental Design) for buildings that has rapidly gained popularity in the U.S. as well as

internationally.

5.1 LEED FOR BUILDINGS

LEEDTM is a rating system for construction of sustainable buildings developed by the U.S. Green

Building Council (USGBC) in the mid 1990’s. The LEEDTM rating system is used as a design and

measurement tool in the building industry, and it serves as a guideline for new and remodeled building projects, promoting sustainable building design. It is also called a design guideline, a

certification standard, or a training program (USGBC 1,2,3,4, 2006).

The first and most used standard “LEED for New Construction and Major Renovations” (LEED-

NC) was introduced in 1996 (v. 1.0). The products have since then expanded to address other

building types including: Existing Buildings Operations and Maintenance, Commercial Interiors ,

Core and Shell Development, LEED for Schools (under development), LEED for Homes (under

development) and LEED for Neighborhood Developments (under development). The LEED for

Neighborhood Development is taking a step to involve impacts outside the actual building

including some, but limited, features related to roadway design as well. Examples of this are

credits such as “Street Network”, “Walkable Streets” and also credits related to stormwater and

erosion and sedimentation control.

5.1.1 LEED Categories And Credits

LEED is a systematically organized system where design teams can aim for a level of


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• Water Efficiency

• Energy and Atmosphere,

• Materials and Resources

• Indoor Environmental Quality

• Bonus Credits for Process and Design Innovation

Each category has prerequisite credits that need to be fulfilled and a number of optional credits

for the project to apply for. In LEED for New construction (LEED-NC, v. 2.2) a total of 69 points

are available within four categories of certification (USBGC 1, 2006):

• LEED CertifiedTM for buildings that earn between 26 and 32 of the available points

• LEED Silver TM for buildings that earn between 33 and 38 of the available points

• LEED GoldTM for buildings that earn between 39 and 51 of the available points

• LEED PlatinumTM for buildings that earn 52 or more of the available points

The project team decides which and how many credits to apply for and provide all the

documentation required by the USGBC. The design team makes sure the features of the credits

are incorporated in the design, and the construction team makes sure the features of the credits are

being met in construction.

5.1.2

LEED And Sustainability

Today there are more then 5000 certified LEED buildings (all levels of certification) in the U.S.

and to some extent internationally, compared to only 100 in 1998 (USGBC, 2007). One of the

major advantages with such a system is the provision of a “checklist” of environmental features

for a project outside the basic requirements, and the creation of a common standard of

measurements for sustainable design.

Meanwhile LEED –NC version 3.0 is under development, some opponents claim a rating system


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years in regards to the use of more sustainable and environmentally sound construction solutions.

For impacts of LEED in the building industry, see Chapter 14; Implementation Strategy and

Impacts.

The rating system developed in this thesis and the definition of elements in a roadway project is a

step in the same direction.


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6. AN ENVIRONMENTAL RATING SYSTEM FOR ROADWAYSPresented in Table 1 is a summary of the suggested main categories and their respective category

intent for an environmental rating system for roadway design and construction. Each category

represent a chapter in this thesis were research provide background for the credit requirements.

Note that all categories are not researched in this thesis (such as Sustainable Alignment) as they

are intentionally left for further research (see Research Objective). This does not mean they are

less relevant or important to include in a final system.

6.1 SYSTEM CATEGORIES – A SUMMARY

Table 1. Summary of system categories and their intent

Category1 Category Intent

Sustainable Alignment(SA)

The intent with this category is to reduce impacts in theenvironment due to the alignment of the road such as:preservation of wetlands, forests, farmlands, and other

ecological sensitive areas.

Materials & Resources(MR)

The intent with this category is to reduce impacts in theenvironment due to material extraction, material use andtransportation.

Stormwater Management (SM) The intent with this category is to reduce major impacts inwater quality and quantity due to polluted stormwater andrunoff.

Energy & Environmental

Contro l (EEC)

The intent with this category is to reduce impacts related to

human and wildlife wellbeing and health such as noisepollution, light pollution and animal crossings. Energyreductions are to some extent included here as it relates tolight pollution and the heat island effect.

Construction Activities(CA)

The intent with this category is to reduce impacts related toconstruction activities such as equipment emissions, fuel use,air-, noise-, water-pollution and improvement of workershealth.

Innovation and Design

(ID)

The intent with this category is to provide an incentive for

innovation and design in a project team.

1 Categories suggested to be included in the full system model


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7. THE CATEGORIES IN DETAIL

The next chapters presents the intent of both the categories and credits that intentionally are left

for further research and also the categories that has been researched in more detail in this thesis.

The researched chapters are structured to give the reader an overview of why the category is

important, present how this relates to roadway construction, suggest design options, analyze

pollution prevention opportunities, briefly describe regulations and policies and finally suggestcredit requirements.


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8. MATERIALS & RESOURCES (MR)

8.1 OVERVIEW

The important issues motivating this category can be summarized in two major points: 1) there is

a growing demand for construction materials, 2) there is an increase in the amount of construction

waste.

The U.S. uses approximately 1.2 billion metric tons of natural aggregate (this include sand and

gravel and crushed stone for construction) every year (Ewell, 2004). 58% of this is estimated to

be used in roadway construction (Carpenter et al, 2006). In 1998 recycled aggregates accounted

for less than 1 percent of the total demand for construction aggregates (Wilburn, 1998). This

number can be assumed to have increased since then, however, the opportunity to use recycled

aggregates in roadway construction is very large.

Integration of recycling and reuse of construction materials in new as well as rehabilitation

construction projects provide environmental as well as economic benefits. These benefits can be

summarized as (Horvath, 1999; Wilburn, 1998; FHWA, 2004):

• Reduce the use of virgin materials• Divert materials from landfills

• Reduce energy consumption

• Reduce emissions

• Decrease costs in construction projects

Use of Virgin Materials:Mining for aggregates are not an infinite source, and quarries in the U.S. as well as around the

world are already starting to shut down due to lack of materials (FHWA, 2004). In Washington

State the extraction of mineral materials for construction related activities stood for 68% of the

total material extraction (in 1997) This is for construction sand and gravel Portland cement and


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Divert material from Landfills:

Landfills require large amounts of land and produce large amounts of emissions. In the United

States, landfills are the largest source of methane (CH4) emissions caused by humans (EPA,

2002). (Methane has a higher Global Warming Potential (GWP) than carbon dioxide (CO2) and is

a huge contributor to climate change, larger then carbon dioxide.) Over 2,100 operational landfills

exist in the United States (EPA, 2002), but many of the landfills in the U.S. are estimated to shut

down in the next 10 years (Amirkhanian, 2001). In Washington State in 2005 there were 18

municipal solid waste (MSW) landfills, 29 inert landfills and 10 limited purpose landfills located

around the state (Washington State Department of Ecology, 2005). Solid waste landfills reported

in 2005 a statewide permitted landfill capacity of 219 million tons, or approximately 40 years at

the current rate of disposal. The reduction of materials disposed in landfills is needed.

Energy & Emissions:

All processes involved in material extraction, production and transportation require energy in

terms of fossil fuels as well as release pollutants and greenhouse gases. Recycling and reuse of

materials can in many cases reduce these impacts in minimizing these activities.

Economic Benefits:

The economical benefits of recycling or reuse of materials can be direct as well as indirect.

Avoided direct costs can be tipping fee’s for material disposal and reduced transportation as well

as production cost due to material recovery. If transportation distances are reduced this can also

have an indirect cost benefit in less wear on the existing roadway system (FHWA, 2004, Horvath,

1999).

8.1.1

Terminology

Terminology is important to provide a uniform language in this credit:

Post-consumer material is defined as “waste material generated by households or by commercial,

industrial and institutional facilities in their role as end-users of the product, which can no longer

b d f i i d d ” (ISO 14021 1999) E l f hi i l i l d


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generated in a process and capable of being reclaimed within the same process that generated it”

(ISO 14021, 1999). Examples in this category include, sawdust, chips, and trimmed materials.

Post Industrial, is a term currently being phased out (according to ISO 14021, 2004), and

replaced by the definition for pre-consumer materials.

Recycled content is defined as the proportion, by mass, of recycled material in a product or

packaging. Only pre-consumer and post-consumer materials shall be considered as recycled

content (ISO 14021, 1999).

Diverted materials are materials that were previously disposed in landfills or incinerators but are

taken from the waste stream as new markets have emerged. This can be construction and

demolition debris that is being reused or recycled.

Inert materials, or wastes, are chemically and physically stable materials that do not undergo

decomposition, such as sand, bricks, concrete or gravel.

8.2 WASTE, RECYCLING & ROAD CONSTRUCTION

The 4 million miles of existing roadways in the U.S. (as mentioned in Chapter 4.1) need regularly

rehabilitation or replacement work. Portland Cement Concrete (PCC), hot mix asphalt (HMA)

pavements and base materials in existing roads, bridges and other infrastructure elements provide

a huge resource of materials for possible future use. Figure 2 present an overview of major

materials to be used in a highway environment. Whereas guardrails, signs and other objects along

the road require materials as well, the major quantities of materials required is in the pavement

structures itself. The Materials & Resources category will focus on these major materials.


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Figure 2. The Highway environment

(RMRC, 2002)

8.2.1 Construction Waste and Recycling

Consistent numbers of building construction and demolition debris can be found (EPA, 1998),

whereas quantities used in road applications are often not studied to the same extent. However,

Figure 3 presents production and consumption of some road construction material in the U.S. that

can be used to get a general idea of quantities by source and market sector (1996 figures) for

roads.


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Figure 3. Production and consumption by market sector

(Quantities are in metric tons. Diagrams are recreated from Wilburn, 1998)

A large part of the crushed concrete debris was in 1996 sent to landfills, and a large part was used

as new road base material. This is the most common way of using recycled concrete in roadway

applications, as described in Design Options. Even if a large part of the crushed PCC still goes to

landfills, the use of recycled PCC is however increasing in construction applications due to new

emerging markets and recycling programs. See Figure 4 for Washington State as an example of

increase in PCC recycling.


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of producing new HMA, see also Design Options, but still some of the recycled asphalt ends up

in landfills or in stockpiles.

One important construction material that is not included in these graphs is steel. Steel is also one

of the most recycled materials in the U.S with around 76 million tons of steel recycled (or

exported for recycling) in 2005 (SRI, 2006), where around 7 millions were used to produce new

reinforcement bars in 2002 (CRSI, 2002). Continuously Reinforced Concrete Pavement (CRCP)

became popular with the construction of the U.S. Interstate Highway system in the 1960’s and

1970’s and hence contains large amounts of steel. Also dowel bars contain steel. It is estimated

that about 65% of all reinforcement bars and nearly 100% of structural steel beams and plates

used in construction are recycled into new products (SRI, 2006). This includes building as well as

road construction steel. There are no separate data available for dowel bars specifically.

8.2.2

Construction Debris in Washington State

The recycling rate of construction and demolition debris has shown to increase dramatically as

the trend of new market areas has developed. In Washington State the Department of Ecology

started to keep track of the diverted materials in 1999 as they noted this very large increase of

material recovery outside the traditional solid waste stream. In 2005 construction and demolition

related materials represented about 95% by weight of the diverted materials reported in

Washington State. Asphalt and concrete alone account for 67% of these total diverted materials

(Washington State Department of

Ecology, 2005). Figure 4 presents as

an example the increased rate of

asphalt and concrete recycling from

the end of the 90’s until today. (Notethat the use of recycled asphalt

pavement (RAP) in new pavement

started much earlier than 1999 but this

i h h D f E l


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There are five major types of final uses for diverted materials defined by Washington State

Department of Ecology. They are 1) transforming or recycling into the same or other products, 2) burning for energy, 3) reuse, 4) use as aggregate material for other products, 5) composting. This

credit will be an incentive to use 1, 3 and 4 of these types of final uses for roadway construction.

8.3 DESIGN OPTIONS

The construction applications presented in Figure 2 that require large volumes of materials can be

defined in major categories (Simon et al, 2006; FHWA, 1997). They are:

(1) Asphalt paving applications

(2) Portland cement concrete applications

(3) Flowable fill applications

(4) Stabilized base applications

(5) Unbound aggregate and fill applications

These applications all have the opportunity to use reused or recycled materials, which for the

most part consists of recycled aggregates. The variability in the products in terms of technical

characteristics can limit their use however the opportunities for innovation and design alternatives

exist. Some material types have one unique final function but there is often more than one final

use for a material depending on the market prices and demand and the amount of research

performed for the specific use. This can provide very important information of feasibility. On

next page, Table 2 presents an overview of the waste or by-product that could be used as a

replacement material to a virgin material in any of the applications listed previously. The table is

extracted from “User Guidelines for Waste and By-products Materials in Pavement Construction”

(FHWA,1997).


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Table 2. Waste or by-products to be used by application

(FHWA,1997) APPLICATION – USE MATERIAL

Asphal t Concrete – Aggregate(Hot Mix Asphalt)

Blast Furnace SlagCoal Bottom AshCoal Boiler SlagFoundry SandMineral Processing WastesMunicipal Solid Waste Combustor AshNonferrous SlagsReclaimed Asphalt Pavement

Roofing Shingle ScrapScrap TiresSteel SlagWaste Glass

Asphal t Concrete – Aggregate(Cold Mix Asphalt)

Coal Bottom AshReclaimed Asphalt Pavement

Asphal t Concrete – Aggregate(Seal Coat or Surface Treatment)

Blast Furnace SlagCoal Boiler SlagSteel Slag

Asphal t Concrete – Mineral Fi ller Baghouse Dust

Sludge AshCement Kiln DustLime Kiln DustCoal Fly Ash

Asphal t Concrete – Asphal t Cemen t Mod if ier Roofing Shingle ScrapScrap Tires

Portland Cement Concrete – Aggregate Reclaimed Concrete

Portland Cement Concrete – SupplementaryCementitious Materials

Coal Fly AshBlast Furnace Slag

Granular Base Blast Furnace Slag

Coal Boiler SlagMineral Processing WastesMunicipal Solid Waste Combustor AshNonferrous SlagsReclaimed Asphalt PavementReclaimed ConcreteSteel SlagWaste Glass

Embankment or Fill Coal Fly AshMineral Processing WastesNonferrous SlagsReclaimed Asphalt PavementReclaimed ConcreteScrap Tires

Stabilized Base – Aggregate Coal Bottom AshCoal Boiler Slag

Stabilized Base – Cementitious Materials(Pozzolan Pozzolan Activator or Self Cementing

Coal Fly AshCement Kiln Dust


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The Swedish Road Administration (SRA, 2004) state leakage from stockpiles is not a “significant

problem” for organic and inorganic substances, however another study (Norrman, 2005) hasshown larger amounts of chloride and lead is indicated in the groundwater due to stockpiling of

RAP.

A study by Legret et al. (2005) comparing new asphalt containing 10% respectively 20% of RAP

shows no obvious difference in leaching rates of heavy metals, even though comparing this RAP

to “regular” HMA indicate that concentrations of total hydrocarbons and some PAHs were higher

in leakage from RAP.

One way to avoid leakage during stockpiling is to cover the piles, however, the importance is also

to find how the RAP perform as part of the pavement structure. More research in various

locations, climates and situations needs to be evaluated to find the true impacts of this material.

Current research performed indicate mixed results.

8.3.2 Recycled Concrete Pavements

Recycled Concrete Pavement (RCP), also known as crushed or rubblized concrete, is reclaimed

PCC pavement material. Primary sources of RCP are demolition of existing concrete pavement,

bridge structures, curb and gutter, and from recyclers who obtain old PCC from

commercial/private facilities (AASHTO, 2005). RCP is also called Recycled Concrete Material

(RCM) or Recycled Concrete Aggregate (RCA). In this report crushed concrete pavement will be

referred to as Recycled Concrete Material as the origin of the PCC can be elsewhere than from

pavements.

The main use of RCM in new pavement structure is as a new base or fill material. In Washingon

State as well as in most States in the U.S. RCM is allowed to be used in road base, as drainage

aggregates and as backfill material (WSDOT, 2004; FHWA, 2004 ). Up to 100% of the base

material could consist of RCM.


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found with workability, decreased compressive strength and higher water demand (FHWA, 2003).

In Washington State RCM as fine aggregate in new PCC is not allowed, see also WARequirements.

As for RAP, there are concerns of leakage impacts using RCM as new aggregates. The reclaimed

concrete has a high alkaline content and a relatively high degree of solubility of these alkaline

materials (AASHTO, 2005). The result is a potential increase in pH that can occur in waters

seeping through the RCM aggregate base or the new PCC.

8.3.3 Steel

Steel is a highly recycled material used as dowel bars or reinforcement in concrete pavements and

bridges. As concrete is demolished and crushed, any reinforcement bars in the structure is

separated as ferrous scrap. The reinforcing bars are then melted down to create new steel products.

There are mainly two processes used to create new steel products; the Basic Oxygen Furnace

(BOF), used primarily for flatrolled steel such as automobile bodies or appliance shells, and the

Electric Arc Furnace (EAF), typically used to create long shapes, which includes reinforcement

bars (SRI, 2006).

In steel recycling the material does not loose its properties and strength. In the process of making

new steel products, old scrap is always used and the demand for steel scrap is even higher than

the availability. This makes steel a strongly recycled material with many opportunities for

recycling over its entire life time.

The recycled content in the production of new reinforcement bars (the EAF method) is as high as

95% (CRSI, 2002). As mentioned previously The Steel Recycling Institute estimates that in 2006around 65 percent of reinforcing bars were recycled (SRI, 2006). This indicates a possibility to

increase the rate of reinforcement recycling.

8.3.4 Blast Furnace slag, Slag cement


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Suggested replacement of portland cement with slag cement is 25-50 % by the Slag CementAssociation (SCA, 2005). This depends on the application and the particluar cicumstaces. It is

substituted for portland cement on a one-to-one basis by mass. The proportions are dictaded by

different requirements for strength, durability, time of set, heat generation, or resistance to alkali

silica reaction (ASR) and sulfate attack. (This is a form of concrete deterioration occurring when

concrete comes in contact with water containing sulfates (SO4)).

Apart from the possibility of replacing some of the portland cement it has other attributes

impacting the concrete. Better workability, higher

strength, lower permeability and improved resistance

to aggressive chemicals (SCA, 2005) are some of the

qualities found by using part slag cement in concrete.

It also has lighter color contributing to higher albedo

conforming to Credit EEC-1 (Chapter 10; Energy &

Environmental Control).

Figure 6. Slag cement

(SCA, 2005)

If used more than 25% in the cement material in PCC it is found that the slag increases the time

of set. When substituted for portland cement in quantities between 25- 65%, slag cement

significantly reduces the permeability (SCA, 2005).

The availability of Slag Cement is in the U.S. is high. However, currently in Washington State

most of the slag used is imported from Japan (Correspondence with Rob Shogren, Technical

Service Engineer, Lafarge North America, February 2007). This does add some cost to the

material however it is still cheaper than conventional cement. The important question is what this

transportation activity does to the environmental impacts embodied in the material. Incentives for


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from combustion in the form of a fine powdery ash (ACC, ACCA, 2006). This material can be

used as replacement for some of the portland cement in concrete pavement as well as fineaggregate in asphalt pavements. It can also be used in stabilized base course, flowable fills and

embankments (FHWA, 2003).

Fly ash is classified as either Class C or Class F, depending on the material’s chemical

composition. Class C ash is also referred to as high calcium fly ash because it typically contains

more than 20 percent CaO. Class F, or low calcium fly ash has less than 10 percent CaO (FHWA,

2003).

Some of the benefits of using fly ash in concrete include increased strength, increased workability,

decreased permeability, reduced heat of hydration, higher resistance to sulfate and other chemical

attack (ACA&ACAA,2006; SCA, 2005; EPRI, 2002). Fly ash is typically used to replace 20-40%

of the Portland cement in a concrete mix (ACAA, 2006, FHWA, 2003).

In asphalt mixtures fly-ash can be used as substitute for some of the fines aggregates, as well as

part of asphalt concrete base courses. Most asphalt mixtures contain 3-7% fine aggregate to

ensure cohesiveness, and base courses usually 12-24%. Fly ash in asphalt pavements is found to

increase the stiffness of the asphalt, improve the rutting resistance of pavements, and thedurability of the mix (FHWA, 2003).

Considerations to take into account in using fly-ash as a replacement in PCC is it can increase air

entraining properties and also has lower early age compressive strength (ERIS, 2002, FHWA,

2003). It is agreed that not all the available fly-ash is suitable for use in concrete. (Malhotra,1999).

The two most important parameters of a fly-ash for concrete use is the fineness and carbon

content.

Availability of fly-ash Class F is limited in Washington. Most of the fly-ash is imported from


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In addition to fly-ash, other coal combustion products can be used as well, such as Bottom Ash

witch is a heavier ash particle that basically falls to the “bottom” of the power plant boiler.Bottom Ash is usually used in structural fill applications and as aggregates in manufacturing of

concrete bricks (ACA&ACAA, 2006).

8.3.6

Glass

Crushed glass or glass cullet, is made of recycled glass products. The quality of the glass varies

and it is important to process it properly to separate the glass from dirt, paper and plastics before

appropriate gradations. If the glass is properly processed it can have characteristics similar to that

of a gravel or sand. It is usually used as a substitution for aggregates in base courses or fills, but it

has also been used as an aggregate substitute in asphalt pavements. Asphalt containing glass

cullet as an aggregate is also called “glassphalt” (NAPA, 2006).

U.S. DOT’s usually allow between 10-20% of crushed glass in base course, and in some cases as

much as 30% in the subbase (RMRC, 2000).

Long term performance of using recycled glass in pavements is at an early stage in research.

Glass aggregate has showed problems in both asphalt concrete and PCC pavements (IDOT, 2002).

In concrete pavements, this material is problematic due to the harmful alkali-silica reaction with

the cement paste. In bituminous pavements, this material bonds poorly to the asphalt, which

results in stripping and raveling problems.

8.3.7 Scrap Tires

In the U.S. approximately 280 million waste tires are produced each year (FHWA, 1997,

Amirkhanian, 2001). In Washington State, approximately 4 million tires were reported as waste

in 2004 (Washington State Department of Ecology, 2005). Of these tires about 55% were

recycled (or diverted), about 23% went to tire-derived fuel, and about 22 % went to landfill

disposal. Over the United States, approximately 800 million scrap tires are currently stockpiled

(Amirkhanian, 2001). This is a huge source of material.


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product resulting from the wet process is called asphalt-rubber cement. In the dry process the

rubber is blended directly into the HMA (Iowa DOT, 2002). The product resulting from the dry process is called rubberized asphalt. The crumb rubber content blended in the mix is usually 12-

25% rubber by weight of mix (FHWA, 1997).

Most laboratory and field experiments indicate that the rubberized asphalt mixtures, in general, show

an improvement in durability, crack reflection, fatigue resistance, skidding resistance, and resistance

to rutting (Hicks et al. 1995; Xiao et al, 2005, Amirkhanian, 2001). Another important finding is the

fact that asphalt containing rubber can reduce tire-pavement noise (Munden, 2006).

The most common objections to using asphalt rubber is high initial costs, issues with recyclability

of the rubberized pavements, hazardous emissions and expensive equipment modifications (to

produce the new asphalt).

8.3.8 Shingles

Shingles contain about 20 % asphalt binder by weight (Mallick et al, 2002) and in many ways

asphalt shingles closely resemble RAP (Amirkhanian et al, 2001). Sources of recycled asphalt

shingle are either the by-product or scrap from the manufacturing of roofing shingle, or, the

construction debris generated when shingle roofs on buildings are removed. Shingles can be used

to modify the asphalt binder, but can also work as an aggregate substitute (FHWA, 1997). Use in

HMA can reduce the need for new asphalt binder significantly, hence cost as well as the need for

new materials.

The results from a study performed in Massachusetts show that the use of manufactured waste

shingles in HMA does not cause a significant difference in the quality of the HMA. The rutting

resistance is even shown to be improved by using manufactured waste shingles. (Mallick et al,

2000). Other benefits using shingle in HMA can be increased stability, decrease in temperature

susceptibility, improved compaction, and improved smoothness (CIWMB, 2006).

M DOT’ i h US ll 5% f h l fi hi l i h l


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8.3.9 Foundry sand

Recycled foundry sand (RFS) or Waste Foundry Sand (WFS) is silica sand with many of the

same properties as natural sands. It is a byproduct of the ferrous and nonferrous metal casting

industry, where sand has been used as a molding material (AASHTO (NCHRP), 2006)

It can be used in many of the same ways as natural or manufactured sands. This includes many

roadway construction applications such as embankments, flowable fill, HMA and PCC (FHWA,

2004). It can also be blended with either coarse or fine aggregates and used as a road base or

subbase material.

Studies have shown that foundry sand can be used to replace between 8 and 25% of the fine

aggregate content in HMA (FHWA, 2004, AASHTO, 2006) and as much as 45% of the fine

aggregate in concrete (AASHTO, 2006).

DOT’s in the U.S allows the use of recycled foundry sand in HMA between 5-20%.

It is important that the foundry sand is cleaned of clay, dust, and other toxic materials.

Additionally, metals present in the sands need to be removed either manually or magnetically.

Foundry sand properties vary in samples taken from one foundry, and there is increased variation

from foundry to foundry. This makes it difficult as a reliable source of material for road

construction.

Foundry sand is gray to black. In some concretes, this may cause the finished concrete to be

darker which may not be desirable.

The leakage rate of chemicals to stormwater runoff from the use of foundry sand is found to not

be worse than that from natural soil (FHWA, 2004).

8.4 POLLUTION PREVENTION OPPORTUNITIES


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The opportunity to use pre-consumer materials (previously post-industrial) as part of a roadway

structure is like described in previous sections big. Fly-ash and slag cement, both materials produced in other industrial processes, are good examples of this. No additional energy is

required, no additional emissions are released as the main process is taking place anyways. Figure

7, 8 and 9 shows comparisons in terms of embodied environmental impacts of fly-ash, slag

cement and conventional portland cement production.

The reduction in embodied green house gas emissions in concrete production is measured by CO2.

By using a 50 percent slag cement substitution as an example, a 42 to 46 percent reduction in

greenhouse gas emissions can be achieved (SCA, 2005).

Figure 7. Effect on embodied greenhouse gas reduction in concrete

(SCA, 2005)

The reduction in embodied energy requirements in concrete production is measured by Mbtu/yd3.

Portland cement constitutes 70 percent or more of the total energy content in concrete (SCA,

2006). Reducing the use of portland cement by substituting a portion of it with slag cement or fly-

ash significantly reduces the embodied energy.


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One ton of Portland cement requires about 1.6 tons of raw material, because of mass lost due to

emissions and other factors (Malhotra,1999) Substituting 50 percent slag cement can save between 6 and 15 percent of embodied virgin material extraction (SCA, 2006).

Figure 9. Effect on embodied virgin materials extraction in concrete

(SCA, 2005)

The opportunity to use post-consumer materials is large too, especially the reuse of demolished

PCC (RCP), reclaimed asphalt pavement (RAP) and base material as discussed earlier.

From a pavement design perspective, recovered materials should be used in such a manner that

the expected performance of the pavement will not be compromised. Increasing the use of

recycled materials can lead to decreased durability of the pavement, as one example. Careful

design and research has to be carried out to find appropriate limitations.

8.5 COST

Cost is an important factor in terms of recyclability and reuse of material and can be an incentive

to use such material. The construction industry is already recognizing the economic benefits of

using recycled materials, such as crushed PCC and aggregates for roadbase, and steel as an

example of very high recycling rate which originally derive from the economical benefits of usingused steel. The cost-effectiveness of substituting conventional aggregate with recycled materials

is highly dependent on the location, the quality and cost of local aggregates. Comparable figures

are very difficult to find in the literature depending on these local conditions and equipment cost.


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On the other hand, if materials are available, reuse of materials that otherwise have to be

transported can be very cost effective. Whatever is the closest and cheapest alternative can beconsidered to be the most attractive.

8.6 LIFE CYCLE ANALYSIS – ENVIRONMENTAL FOCUS

Discussing materials and resources and their environmental impacts is not only about

recyclability and the reuse of materials. One of the most important approaches to every design

that should be made is to look at the total life cycle impacts of the material. Life cycle analysis

(LCA) focusing on cost is usually carried out for projects. Life cycle analysis focusing on

environmental impacts is related to these costs and has to be considered as well.

The life cycle consists of many different processes and activities and for a pavement construction

the main activities can be categorized in: the extraction of the material, the production of the

material, all the transportation activities related to these activities, the construction activitiesrelated to the placement of the material, the maintenance activities related to the structure and the

end of life of the pavement.

All these stages uses material’s, require energy and release emissions contributing to the overall

environmental impacts from the pavement over its entire life. All these stages also relate to many

other activities and processes that use materials, consume energy and release emissions as well.

The “cradle to grave” of many processes that interrelate is included in a LCA. Chemical leakage,

the embodied energy content and the embodied greenhouse gas emissions are some measures that

can give a sense of how the materials really perform. Using virgin materials may not be superior

to using recycled materials (Carpenter et al, 2006).

Using recyclable materials may decrease the life of the pavement, and if this is the case, the

overall embodied energy content and embodied emissions content might be higher than if using

conventional materials (due to the increase in construction and maintenance activities this shorter

lif f th t t b i )


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what material flows to study. Once performed however, it can provide the very useful information

needed to decide weather one approach is superior to another.

8.6.1 LCA Tools for Pavement Design

The Pavement Life-cycle Assessment Tool for Environmental and Economic Effects (PaLATE)

is a design tool developed at the University of California at Berkeley for the Recycled Materials

Resource Center (RMRC) and the FHWA (Horvath, 2003). It provides a life-cycle assessment

(LCA) framework and computer-based tool including environmental and economic parameters

for evaluation of pavement construction. The purpose of this tool is to assists decision-makers in

evaluating the use of recycled materials in highway construction and maintenance activities

(Horvath, 2003).

This tool evaluates the environmental performance of emissions and energy use associated to

construction, transportation and maintenance of asphalt and Portland cement concrete pavement,subbase, embankment and shoulder material. It provides an assessment of the use of recycled

material from demolished pavements as well as an assessment of industrious by products that

may be used in road construction and pavement structures. It also performs an analysis of life

cycle costs. The results between different design alternatives can be compared to each other in

regards to these environmental as well as economical performances.

The results are provided in graphs describing each phase, effects from processes, material

transportation and materials production. This tool can be very helpful in deciding between design

options and the feasibility of actual environmental and economical impacts. Credit will be given

for analysis performed in PaLATE.

8.7 TRANSPORTATION ACTIVITIES

The effects of transportation on fossil fuel consumption and the resulting pollution is well

established and it is significant (EPA, 2002). The construction of roads certainly include large

masses of materials that needs to be transported over great distances. This impact not only release


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ash and slag cement as replacement in PCC is increasing in Washington state, but the availability

of theses materials from this region is low. Large quantities of slag cement is imported andtransported from Japan. Fly-ash is available in Washington State and in Oregon, but large

quantities are also imported from Alberta, Canada. This needs to be addressed and could be

considered in an LCA. Additionally, to use regional or local products can support regional

economies by promoting growth for local businesses. See Appendix A for evaluation of

recyclable materials and their availability, and see Appendix E for available virgin quarries and

pits in Washington State used by WSDOT for HMA and PCC pavements.

LEED-NC (v. 2.2) credit MR 5 award “building materials or products that have been extracted,

harvested or recovered, as well as manufactured, within 500 miles of the project site for a

minimum of 10% (based on cost) of the total materials value”. This measure can provide an

incentive for the above mentioned aspects and this credit will be adapted to this system as well.

8.8 REGULATIONS IN WASHINGTON STATE

WSDOT Standard Specifications (WSDOT, 2006) state requirements and limitations for the use

of recycled content in materials in pavement applications. Before setting criteria limits, these

regulations needs to be considered. General Requirements for Recycled Materials are stated in 9-

03.21.

Asphalt concrete pavements

The contractor has the option of utilizing recycled asphalt pavement (RAP) up to 20% of

the total weight of the aggregates (5-04.2). The RAP may be from pavements removed

under the contract, if any, or pavement material from an existing stockpile. For Ballast,

Crushed surfacing and Gravel Backfills the limit is set to 1.2 % (of the binder) (9-

03.21(2)).

Fly-Ash

Fl h b d i t t t d h ll t d 35 % b i ht


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Slag Cement (Ground Granulated Furnace Slag)

Ground granulated blast furnace slag may be used and shall not exceed 25 % by weight

of the total cementitious material (5-05.3(4)) and shall conform to (9-23.10).

When both ground granulated blast furnace slag and fly ash are included in the concrete

mix, the total weight of both these materials is limited to 35 % by weight of the total

cementitious material.

Blended Hydraulic Cement

As an alternative to the use of fly ash, ground granulated blast furnace slag and cement as

separate components, a blended hydraulic cement may be used (5-05.3(4)). It shall

conform to AASHTO M 240 and the Types as described in (9-01.2(4))

Recycled Portland Cement Concrete Rubble

May be used as or blended up to 100% with ballast, shoudler ballast, crushed surfacing

base and top course, gravel aggregate, gravel backfill and as foundation material Class A,

B and C (9-03.21(3)). RCM is not allowed as fine or coarse material in new PCC or as

aggregates in HMA or as Asphalt treated base.

Glass

Recycled glass may be used as ballast, shoulder ballast, crushed surfacing and gravel

aggregate up to 15% by weight as noted in 9-03.21(4). As foundation material and gravel

backfill in certain situations 100% glass may be used as stated in 9-03.21(4).

These are the mentioned recyclable materials in WSDOT specifications. As mentioned previously,

there are other materials to be used as replacement of virgin materials and these could be

considered as well. Following information in addition to the specifications was retrieved by

correspondence with Linda Pierce, State Pavement Engineer, WSDOT, February 2007:


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8.9 CRITERIA DEFINITIONS

A total of 8 credits can be achieved in this category; Materials & Resources (MR).

Table 3. Credits available in category Materials & Resources

Materials & Resources (MR) Credits

Construction Waste Management 1

Reuse of Pavement 1 1

Reuse of Pavement 2 1

Recycled Content 1 1

Recycled Content 2 1

Life Cycle Analysis 2

Regionally Provided Material 1

Total credit s available 8

Environmental credit is given to reuse and recycling of asphalt, PCC and other pavement

materials to substitute for virgin material production and minimize impacts related to this activity.

The life of recycled pavement materials starts at breaking up existing old pavement, followed by

transportation to deposit or asphalt/concrete plant, followed by crushing, mixing of new pavement

material and transportation to the location of the new pavement.

The life of pre-consumer materials starts at the end of the manufacturing process, such as the

product of fly-ash in the combustion process, or slag cement in the furnace.

A description of the credits with their intent and requirement follow.


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8.9.1 MR-1. Construction Waste Management

The intent of this credit is to reduce the amount of waste going to landfills or incineration and

provide an incentive to include waste management practices in the project.

Construct ion Waste Management 1 Credit

Recycle or salvage at least 70% of non-hazardous construction and

demolition debris.

A plan for handling construction waste in the project should be submitted including calculation of

percentage of construction demolition waste (CDW) according to the recycling rate calculation

(modified from LEED v. 2.2):

[ ] [ ]

[ ] [ ]volumeaste LanfilledW volumeecycledWast volumeecycledWast

ecyclingRat CDW +

=Re

Re%Re

The Plan should include:

• Quantities of construction waste generated presented by application.

• A plan for processing, transportation and disposal of the waste.

• A description of all material being disposed and location of disposal.

• A description of recycled waste going back to manufacturing process and a description

of possible reuses in current or future projects.

Comments:

A possibility of earning a greater beneficial impact from the Construction Waste Management

credit could be to weight specific wastes depending on their impacts in regards to availability and


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The 70% limit comes from the fact that about 67% of total diverted materials related to

construction in Washington State account for asphalt or concrete debris as described in Chapter

8.2.2., Construction Debris in Washington State. (Diverted material means materials taken from

the solid waste stream that previously ended up in landfills but now are being used in new

products). These numbers are approximate but can give an indication of quantities that are being

reused or recycled.


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8.9.2 MR-2. Material Reuse 1

The intent of this credit is to salvage construction materials in the project to reduce the extraction

of virgin materials and/or production of new materials including all processes involved in theses

activities.

Reuse of Materials 1 1 Credit

Maintain 85% of the existing pavement material in new pavement

structure as base material or as total construction material based on

weight.

This credit is intended mainly for rehabilitation work.

Example:

Reuse PCC pavements, asphalt pavements or reuse native soil, sand, gravel and rocks for new use

in top courses, base courses, embankments and fills.

[ ] [ ][ ]tonsal BasemateritonsalusedmateriusedRate Re%Re =

Or

[ ] [ ]

[ ]tonsialTotalMater tonsalusedmateri

usedRateRe

%Re =

A description of the material to be reused and its new application should be submitted together

with the estimates.


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8.9.3 MR-3. Material Reuse 2

Same intent as MR-2, with further incentive for material reuse.

Reuse of Materials 2 1 Credit

Maintain additional 10% (Total 95%) of existing pavement materials in

new pavement structure as base material or total construction material

based on weight.

Same requirement and calculation as MR-2.

Comments:

Analysis of different pavement types, rehabilitation of commonly used pavements in Washington

State, and the reuse of variations of the materials are evaluated to set the criteria limits. See

Appendix B for example.

The idea of credit MR-2 and MR-3 is derived from LEED-NC v. 2.2 credit MR 3.1 and 3.2,

Materials Reuse in Materials and Resources.


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8.9.4 MR-4. Recycled Content 1

The intent of this credit is to promote the use of recycled material to minimize the extraction of

virgin materials and impacts from production processes as well as reduce waste.

Recycled Content 1 1 Credit

Use recycled content to a minimum of 25% in the HMA/PCC and 40% of

the total material in the structure if base course is included in the project.

Recycled content is based on replacement of conventional material to a percentage based on the

weight of the aggregates. For assembled materials, calculate the recycled content specifically for

the assembly.

Example:

Binding mediums material would be one assembly group, aggregates used another, steel another,

etc. Use the Application Table 2 in Design Options for assembly groups. See Appendix B for

Tesis - Diseño Sostenble de Una Carretera- Metodo Leed

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