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2024 | Book

Pavement, Roadway, and Bridge Life Cycle Assessment 2024


Editors: Gerardo W. Flintsch, Eugene A. Amarh, John Harvey, Imad L. Al-Qadi, Hasan Ozer, Davide Lo Presti

Publisher: Springer Nature Switzerland

Book Series : RILEM Bookseries


About this book

This book highlights the latest advances, innovations, and applications in the field of LCA in pavements, bridges, and roadways, as presented by leading international researchers at the 6th International Symposium on Pavement, Roadway, and Bridge Life Cycle Assessment (ISPRB LCA2024), held in Arlington, VA, USA, on June 6–8, 2024. It covers a diverse range of topics concerning assessment of environmental impacts of pavements, bridges, and roadways, including environmental product declarations (EPDs) and use of life cycle assessment (LCA) in design, data, and case studies: LCA methodologies for transportation infrastructure, durability and service life assessments, maintenance strategies to enhance performance and minimize environmental impacts, evaluating the environmental impacts of materials and construction, recycling and reuse of materials, carbonation of concrete, pavement vehicle interaction, life cycle thinking in climate change planning, and climate change mitigation. The contributions, which were selected by means of a rigorous international peer-review process, present a wealth of exciting ideas that will open novel research directions and foster new multidisciplinary collaborations.

Table of Contents

Quantitative Measures of Social Sustainability for Pavements: Future Directions for Implementation
Pavement sustainability requires balancing economic, environmental, and social factors. However, the social aspect is often less studied and harder to measure, making its integration into life cycle approaches complex. Recent policies like the Justice40 initiative and the Bipartisan Infrastructure Law have highlighted the necessity for fair infrastructure, emphasizing the importance of concrete social sustainability measures. Current methods like social life cycle assessment (S-LCA) tend to concentrate more on social governance and human well-being, rather than providing a tangible measure of how pavement investments affect individuals. This research summarizes a new method to measure the effects of road conditions on marginalized groups, particularly environmental justice (EJ) communities. It stresses the need to include social factors in assessing pavement sustainability. This approach evaluates the impact of road conditions on both EJ and non-EJ community members and road users. It examines fuel usage during commutes in relation to pavement quality in these areas. Finally, the study discusses future research directions for the methodology’s usage in life cycle frameworks such as LCA and LCCA.
Egemen Okte, Jessica Boakye, Mark Behrend
Assessing the Ecological Impact of Different Asphalt Mix Designs Following a Cradle-to-Gate Approach
The consequences of climate change are becoming increasingly noticeable and require a more economical use of resources and energy in all areas, including road engineering. To optimize such construction processes, a comprehensive assessment of the respective impacts is essential. By conducting a Life Cycle Assessment (LCA) according to ISO 14040/44, following a cradle to gate-approach (Module A1–A3 according EN 15804), the focus of this study is set on manufacturing (Module A3). Production data from an asphalt mixing plant with possible addition of cold recycled asphalt pavements (RAP) has been collected and analyzed to identify and evaluate various indicators which may have an influence on the energy consumption of the drying drum. In addition, a suggestion to sensibly cluster asphalt mix designs into groups according to their respective energy consumption for production and their components will be presented, in order to be able to compare the ecological impacts of different mix designs based on their Global Warming Potential (GWP). The results have shown that the addition of RAP and/or polymer-modified bitumen (PmB) are increasing the fuel consumption and consequently the GWP in Module A3. However, when considering the whole product phase (Module A1–A3), this additional emission can be offset with the benefits in Module A1 by the addition of RAP.
Paul Schoenauer, Michael R. Gruber, Bernhrad Hofko
Effect of Transportation on Environmental Burdens of Blended Cements Made with Imported and Domestic Supplementary Cementitious Materials
Cement accounts for 7% to 8% of global anthropogenic emissions. An effective strategy to reduce concrete emissions is partially replacing cement with supplementary cementitious materials (SCMs) such as coal fly ash and slag. However, the available supply of these industry byproduct SCMs is rapidly diminishing in the United States. Consequently, they are transported from distant regions. However, the effect of transportation distance on the global warming impact (GWI) of SCM-blended cement remains unknown. A cradle-to-gate life cycle assessment showed that the GWI of 1 metric ton (tonne) of blended cement with 20% coal fly ash imported from Asia is approximately 3% lower than 1 tonne of cement based on the U.S. national average GWI for cement. The reduction was almost 14% when coal fly ash was from Texas and approximately 17% when a locally produced natural pozzolan was used. The results show transportation could significantly affect the environmental benefits of blending cement with SCMs.
Ali Azhar Butt, Somayeh Nassiri
Updates and Demonstration of the FAA Airfield Life Cycle Assessment Tool “FAALCAn”: A Taxiway Case Study
The airports in the United States increasingly require an ability to quantify their environmental impacts from airfield infrastructure and to consider these impacts in airfield management, conceptual design, design, materials selection, and construction project delivery decisions. A web-based airfield pavement life cycle assessment (LCA) tool, “FAALCAn”, is currently being developed following the Federal Aviation Administration Pavement LCA Framework for national use. The user interface allows users to input foreground data to create their own materials, mix designs, orders of work for construction equipment, equipment types, and transportation modes and distances; users can also update electricity production and fuel type to reflect local conditions, along with other project information. The background data has been acquired from the Federal LCA Commons repositories. The tool can be used to perform complete airfield pavement LCA for any project. An asphalt pavement taxiway case study has been performed to demonstrate the use of the tool in this paper.
Ali Azhar Butt, Nathaniel Titterton, John Harvey, Iyanuoluwa Filani, Navneet Garg
Recommended to Include Relevant Material Performance in the Construction Material Environmental Product Declarations
The use of cradle-to-gate environmental product declarations (EPDs) can be an important part of the implementation of life cycle thinking to improve the sustainability of civil infrastructure. The use of EPDs in procurement of materials for civil infrastructure has been of increasing interest to state and local agencies, and implementation has been driven in part by legislation. However, EPDs need to be specified and managed well to make them an efficient and reliable tool for helping to improve environmental sustainability. In 2023, a white paper was published reviewing the use of EPDs, provided a summary of several important problems identified with the approach that has been implemented to date, and offered recommendations to improve the practicality of EPDs, reduce their cost, and increase the environmental improvements that they can help produce. One of the recommendations was to use a full life cycle perspective capturing the performance of the materials for well-informed decision making. This is because transportation of materials from the manufacturing site to the construction site are not considered in cradle-to-gate EPDs. Furthermore, a material that has a lower cradle-to-gate impact may not last as long, may require more maintenance, or may not be equally recyclable at the end of life as an alternative material and, therefore, might produce more impacts over the life cycle. In this paper, a full pavement life cycle assessment is performed to demonstrate quantitatively the arguments above.
Ali Azhar Butt, Rongzong Wu, John Harvey
Life Cycle Assessment of Asphalt Concrete Construction Stage and Impacts of Construction Equipment Idling
The National Asphalt Pavement Association (NAPA) has developed an Environmental Product Declaration (EPD) program that effectively measures the cradle-to-gate life cycle stages of asphalt pavement. However, there is limited information available regarding the construction stage of asphalt pavement in life cycle assessment (LCA). This paper aims to address this gap by quantifying the environmental impacts of the construction stage (A4 and A5) of asphalt pavement for 11 test sections. These sections include eight from the 2022 MnROAD experiment, which featured asphalt mixtures with recycled rubbers, recycled plastics, and synthetic fibers, and three from the Federal Highway Administration (FHWA) Climate Challenge project on US-82 in Alabama, which used asphalt mixtures containing synthetic fibers and warm mix additives. LCA of the construction stage of the 11 test sections was conducted by combining foreground data collected during construction with life cycle inventories for off-road equipment from the Environmental Protection Agency (EPA). Furthermore, data on the idling of construction equipment due to mix delivery delays were gathered and analyzed to determine the effects of these delays on emissions. Initial findings indicate that eliminating the idling of construction equipment by maintaining a balance between production, trucking, and paving could lower greenhouse gas emissions by 8% to 21%.
Surendra Chowdari Gatiganti, Benjamin F. Bowers, Nam H. Tran
Life Cycle Cost and Environmental Impacts of Portland Limestone Cement and Calcium Sulfoaluminate Cement as Alternative Binders in Concrete
Use of portland limestone cement (PLC) instead of ordinary portland cement (OPC) Type I/II in conventional concrete pavement and calcium sulfoaluminate (CSA) cement instead of OPC Type III in rapid strength concrete (RSC) are commonly proposed strategies that could reduce greenhouse gas (GHG) emissions for the Caltrans highway network and meet the state’s climate change mitigation goals. This study aims to quantify the potential global warming abatement cost of PLC and CSA cement use in California at the project and network level using life cycle cost analysis and life cycle assessment and to determine the benefits and disbenefits of the two proposed cement types. Results from the analysis showed that the abatement cost for replacing PLC with OPC Type I/II is $180/tonne of CO2-eq reduction, while the cost for replacing OPC Type III cement with CSA in RSC is $1,422/tonne of CO2-eq reduction.
Iyanuoluwa Filani, Ali Azhar Butt, John Harvey
RolRoad – LCA: A Web-Based Application for Estimating the Excess Fuel Consumption and Environmental Impacts Due to the Rolling Resistance of Passenger Cars
This paper presents RolRoad – LCA, a web-based application for estimating rolling resistance (RR) and its effect on excess fuel consumption (EFC) of passenger cars driving on flexible road pavement. RolRoad – LCA relies on machine learning models developed based on data collected with an instrumented vehicle at the University of Gustave Eiffel’s test track. It is intended for project-level analysis and considers the effects of roughness, expressed in terms of the international roughness index (IRI), and macrotexture, expressed in terms of mean profile depth (MPD), on RR and EFC. Further, it allows the execution of three types of analysis: single-year, multiple-year considering linear degradation of pavement surface properties, and multiple-year considering non-linear degradation. The life cycle inventory associated with EFC is calculated according to the dataset corresponding to the operation of a standard passenger car powered by gasoline with an engine complying with the EURO 5 standard. The resulting environmental impacts are expressed in an environmental cost indicator (MKI), which is a single-score indicator expressed in Euros, that aggregates different midpoint impact category scores. RolRoad – LCA offers the pavement community an expedient and accessible application to quantify and compare the effects of different pavement surface properties and maintenance and rehabilitation (M&R) strategies on the EFC and corresponding environmental impacts. It can be used as a standalone tool or complement the use of generic or pavement-specific life cycle assessment (LCA) software.
Ida Uva, João Santos, Veronique Cerezo, Seirgei Miller
Estimating Pavement Cost in Texas Using a Mechanistic-Empirical Proportional Consumption Approach
The state of Texas heavily relies on its extensive surface transportation network to facilitate the safe and efficient movement of goods and people. However, the increased demand for roads, alongside limited funding exacerbated by the rise of fuel-efficient and electric vehicles, has led to a higher-than-normal deterioration of the highway infrastructure. To address this issue, the Texas Legislature has explored alternative funding sources and strategic budget allocation options. A promising approach involves revising the permitting fee structure for oversize and overweight (OS/OW) vehicles to reflect their pavement consumption costs, which could significantly contribute to pavement maintenance funding. This study proposes a modular approach, which incorporates traffic data, to calculate overall pavement consumption costs per mile for different truck loads and configurations, as well as pavement types and failure criteria. This approach enables a more data-driven framework to adjusting the OS/OW permit fees. The methodology incorporates the equivalent consumption factor to estimate pavement performance, and vehicle miles traveled to account for the traffic volume. The findings offer valuable insight into pavement lifecycle analysis, highlighting a viable funding mechanism through the adjustment of permit fees to supplement maintenance costs, thereby supporting a sustainable long-term pavement management program in Texas.
Danilo Keniti Nais Inoue, Jorge Alberto Prozzi, Christian Andres Sabillon-Orellana
Case Study: Cradle-to-Laid Life Cycle Assessment of a Concrete Pavement Reconstruction Project in Colorado
This study presents a cradle-to-laid Life Cycle Assessment (LCA) of the Global Warming Potential (GWP) impact of 1 lane mile of a concrete pavement for a highway construction project in Colorado. For this study, cradle-to-laid includes the A1–A3 modules of the production stage and the A4–A5 modules of the construction stage according to the ISO LCA methodology. Quantity takeoffs of materials were calculated from the project’s construction drawings, pavement design report, general contractor’s production metrics, and Colorado Department of Transportation (CDOT) project-specific mix design data. The GWP impact values for concrete production were obtained from a facility-specific concrete cradle-to-gate LCA, with values sourced from project estimated quantities, LCI data from the National Ready Mix Concrete Association (NRMCA) Rocky Mountains regional concrete benchmark, and LCI data from FHWA’s LCA Pave tool. For production of aggregate base course, installation of dowel bars and tie bars, and transportation and construction of all pavement materials, GWP impact values were extracted from the FHWA’s LCA Pave tool software. The results presented in this paper could be used by agencies or practitioners as a case study for LCA of the construction of a concrete highway pavement.
Christopher T. Senseney, Daniel Donado Quintero
Are Low-Temperature Asphalts a Good Choice?
In the last few years, European and international policies set the objective of achieving high levels of health and environmental protection. For preventing and reducing the environmental effects of asphalt pavements, life cycle assessment (LCA) is widely recognized as a critical tool to systematically monitor and control life-cycle-related impacts, from the extraction of raw materials, through production, transportation, and manufacturing, to the end-of-life phase. Using an LCA-based method, this study discusses the impacts related to two different bituminous mixtures, focusing on assessing the potential sustainable performance of including both recycled and virgin materials. The comparative analysis involves two mixtures: a warm asphalt mixture (WMA) including crumb rubber from end-of-life tyres and recycled mineral oil, and a conventional hot mix asphalt (HMA) (dense-graded) mixture. The specific purpose of this work is to quantify the greenhouse gas (GHG) emissions and resource consumption associated with the selected solutions, providing insights and broadening knowledge for the use of sustainable materials and related new processes in the field of road construction, from an environmental perspective.
Filippo Giammaria Praticò, Giusi Perri
Environmental Product Declarations: Effects of Scope of Consideration and Design Approach on the Results of Life Cycle Assessments
One challenge in using Environmental Product Declarations (EPDs) effectively in construction projects is ensuring the standardization of Product Category Rules (PCRs) and Life Cycle Assessments (LCAs) so that comparable products are evaluated consistently. When conducting LCAs for construction projects, alternative design approaches often involve the substitution of products from different categories to achieve the desired result. In this scenario, an analysis which simply compares the EPDs of the alternative products may yield flawed results because the differing design approaches will have effects which extend beyond the products themselves. To capture a true comparison of the environmental impacts, the scope of consideration for the LCAs must extend beyond the EPDs and account for all impacts resulting from each design approach. The importance of adopting a proper scope of consideration for LCAs can be demonstrated through the example of a flexible pavement with alternative designs using a conventional approach and a mechanically stabilized aggregate layer for enhanced performance. Sample analyses are presented showing the effects of the scope of consideration and the sensitivity of the results to the variables considered. The objective of the study is to highlight key considerations for accurate LCAs, the importance of establishing standard factors and approaches, and the necessity of a comprehensive approach.
Bryan C. Gee, Paul Schmitz
Strategies for Reducing CO2 Greenhouse Gas Emissions in the Flexible Pavements Life Cycle
Climate change has become an emerging topic that many global countries can no longer ignore. The U.S. Government’s policy is to improve the nation’s preparedness and resilience to the effects of a changing climate by targeting net-zero greenhouse gas (GHG) emissions by the year 2050 and limiting global warming to an increase of 1.5 ℃. The Department of Defense (DOD) is developing strategic processes to ensure net-zero GHG emissions from federal procurement. A paper, submitted to this symposium, explored documented baseline carbon dioxide equivalent (CO2e) GHG emissions associated with construction, maintenance, and rehabilitation of flexible pavements, as well as opportunities for reducing CO2e GHG emissions. This paper formalizes strategies for reducing CO2e GHG emissions for the flexible pavement life cycle and develops CO2e GHG emissions for optimized strategies. The strategies are categorized as (1) pavement design, (2) materials, (3) equipment, (4) processes, and (5) disposal (end-of-life). Optimized strategies are highlighted using an airfield pavement case study.
Athar Saeed, Jeb S. Tingle, Charles Williams
Evaluation and Documentation of Production and Reduction Methods for Greenhouse Gas Emissions in Flexible Pavements
The United States Government has committed to improving the nation’s preparedness and resilience to the effects of a changing climate by targeting net-zero greenhouse gas (GHG) emissions by the year 2050 and limiting global warming to an increase of 1.5 ℃. The Department of Defense’s (DOD) role is to develop strategic processes to ensure net-zero emissions from the federal procurement. The DOD’s Climate Adaption Plan outlines five Lines of Efforts (LOEs). LOE 1 considers social costs of GHG emissions in cost-benefit and life-cycle analyses, and LOE 4 deploys GHG emission reduction construction technologies. This paper synthesizes GHG emissions data from the literature to provide a range of expected (baseline) GHG emissions associated with a flexible pavement’s life cycle from documented and published sources. This paper also explores opportunities for reducing GHG emissions that were identified in the literature. A second paper will formalize strategies for reducing GHG emissions for the flexible pavement life cycle and develop GHG emissions associated with optimized strategies.
Athar Saeed, Jeb S. Tingle, Charles Williams
Permeable Pavement Systems: Sustainable Case Studies
Structurally resilient and functionally sound pavements should withstand excessive water run-off. Permeable pavement systems (PPS) may be used to reduce runoff, improve effluent water quality, and/or achieve psychosocial, societal, and sustainability benefits. The recent advances in pavement material and construction techniques, structural and hydraulic designs, drainage, and new approaches to measure filtration present an opportunity to quantify the environmental benefits of PPS. This paper presents the environmental impacts of integrating PPS in urban areas, including the effects on life cycle assessment, sustainability, and resiliency. The outcome is presented from case studies in the USA (Oregon, Missouri, Minnesota, Louisiana, Wisconsin, New Jersey, and Georgia), as well as international case studies (China, Australia, The Netherlands, and UK). Some of the case studies include conventional impervious surfaces for comparison. Based on these case studies, it is evident that the implementation of PPS in cityscapes could offer several benefits.
Issam I. A. Qamhia, Imad L. Al-Qadi, Hasan Ozer, Amir Golalipour
Study on the Mechanical Behavior and Environmental Product Declarations of Road Base Layers Incorporating Anhydrous Calcium Sulphate
The adoption of circular economy principles and environmentally sustainable engineering is becoming increasingly prominent in civil engineering. Portland cement (PC) production alone is responsible for 8% of total annual CO2 emissions. Novel materials should possess good mechanical and physical properties while reducing CO2 emissions. This study analysed different mix designs for cement bound granular material (CBGM) road layers, partially replacing PC with anhydrous calcium sulphate (ACS), an industrial by-product. The objectives of the study include assessing mechanical performance through laboratory tests and analysing Environmental Product Declarations (EPDs) for each mix design. Two mix designs were examined: one with 3% ACS and 2% cement, and the other mix with 4% ACS and only 1% cement. Hydraulic binders used in the mixes included PC, Green Cement (GC), and ACS, with variations of aggregate types, natural and recycled. Innovative mix designs demonstrate comparable strengths to traditional CBGM layers. This paper aimed to analyse the environmental impacts using EPDs, comparing innovative mixes to those with 5% PC and 5% GC to identify environmentally friendly mixes with appropriate mechanical responses.
Andrea Serpi, James Rombi, Mauro Coni, Francesca Maltinti
Renewable Fuel for Asphalt Concrete Production to Reduce Carbon Emissions
A recent analysis of Oregon Department of Transportation (ODOT) activities found that the largest source of greenhouse gas emissions comes from asphalt concrete pavement (ACP) production. An average of 65,200 MT CO2e is released into the atmosphere each year from the production of ACP used by ODOT. One of the key recommendations from the aforementioned research study was to substitute renewable fuels for fossil fuels at industry plants.
In September 2022, ODOT partnered with the Asphalt Pavement Association of Oregon (APAO) and an Oregon-based asphalt contractor to test the viability of using renewable propane at a mobile asphalt plant. The project provided an ideal comparison between fossil and renewable propane since the contractor used conventional propane before and after the test section, the weather was consistent, and the paving type and tonnage were identical among the shifts. The contractor reported no noticeable differences between conventional and renewable propane except for the price.
The major objective of this study was to perform a life cycle assessment (LCA) for renewable propane to determine its environmental impact on asphalt production. The outputs from the renewable propane LCA were incorporated into another asphalt LCA tool (Emerald ECO-Label) to quantify the impact of using renewable propane on the CO2 emissions of a typical asphalt plant in Oregon. The outputs allowed for an apples-to-apples comparison between fossil propane and renewable propane. These outcomes will enable asphalt plant operators and asphalt customers to make more informed decisions on where, or how, to focus sustainability efforts.
Erdem Coleri, Zechariah Heck, John Hickey
Integrating Corporate GHG Protocols Scope 1, 2, and 3 into Product Life Cycle Assessments
There is a growing trend of policies being developed to encourage companies to decarbonize. While some policies focus on corporate sector analysis, others focus on product level analysis using life cycle assessment. Corporate greenhouse gas (GHG) accounting follows the GHG Protocol Corporate Accounting and Reporting Standards. Use of the GHG Protocol has been primarily voluntary for US companies. However, current proposed regulations could require corporate GHG accounting for federal contractors as well as publicly traded companies. In addition, for construction products, green public procurement policies are being introduced that require cradle-to-gate life cycle assessment information reported through Environmental Product Declarations following ISO standards.
The GHG Protocol classifies and reports GHG emissions into three scopes, distinguishing direct emissions from indirect: Scope 1 are the direct emissions from an organization’s facilities; Scope 2 are the indirect emissions from purchased electricity, steam, heating or cooling; and Scope 3 are the indirect emissions related to upstream and downstream activities. Environmental Product Declarations for construction materials typically report the cradle-to-gate (A1–A3) production stage GHG emissions, which are further separated into (A1) extraction, (A2) transportation, and (A3) manufacturing modules. This paper seeks to map these two reporting mechanisms for various business structures common to infrastructure construction.
Peter Bacas, Heather Dylla
Data Specificity of Concrete Mixture Environmental Product Declarations
The objective of this research is to determine the data specificity needed to develop concrete mixture environmental product declarations (EPDs) that estimate global warming potential (GWP) with appropriate precision and accuracy. Several agencies in the United States are integrating construction materials EPDs into Green Public Procurement processes. These agencies, however, are struggling to determine how to balance the need for product-specific EPDs with incorporation of upstream industry average data, causing decision-makers to question the appropriate level of specificity to represent a “supply chain specific” EPD. Higher levels of specificity increase the burden of life cycle information development and associated cost. Therefore, the question centers on what level of specificity is adequate that beyond which the increased cost of specificity does not further aid discernment. This study addresses these knowledge gaps by investigating the data specificity needed for each component of a concrete mixture EPD (incorporating data for life cycle stages A1 through A3) to reach an acceptable level of certainty regarding the product GWP presented in the EPD. Using this data, agencies can identify for themselves what level of uncertainty is acceptable for their needs and set procurement thresholds that consider a specific amount of known uncertainty.
Michelle A. Cooper, Amlan Mukherjee
Evaluation of LCA Tools for Road Construction and Operation Purposes: A Case Study in Nordic Europe
Numerous life cycle assessment (LCA) tools for roads are available in Finland and the Nordic countries. These are distinct in aspects such as the LCA stages and standards they are based on, ultimately limiting their capabilities to comprehensively perform an LCA encompassing the use stage. Despite the prevailing differences, adequate studies have yet to be performed to assess and compare these tools. This research evaluated the possibility of combining two LCA tools, ZEROInfra and FuelSave, developed for road construction and operating purposes, respectively, and used by Ramboll Finland Oy, a major consultant in Finland. Additional LCA tools, such as VegLCA from Norway and Klimatkalkyl from Sweden, are incorporated to compare the emission estimations for the product and construction stages of LCA. With the same system boundary, the results showed that emissions estimated by ZEROInfra, Klimatkalkyl, and VegLCA were equivalent, reporting results between 2.4 to 2.5 kt of CO2 eq. However, the environmental impact of each component work item varied due to the differences in aspects such as material property and equipment assumptions by each tool and the aggregation of work items to fit into the input features of the tools. The operation stage of LCA from vehicles was estimated by FuelSave, which resulted in 124 kt of CO2 for 20 years, showing that the dominant contribution to the environmental impact originates from this stage of LCA.
Tewodros Dugasa Gebre, Di Wang, Noora Eklöf, Augusto Cannone Falchetto
Piloting Life Cycle Assessment: Experiences from Alabama, Louisiana, Mississippi, and Virginia Departments of Transportation Case Studies
There is growing interest for state departments of transportation to identify practices that reduce the embodied carbon of infrastructure. To achieve this, there is a need to understand the embodied carbon related to current pavement construction practices. Despite significant progress in standardizing how the environmental impacts of our pavement’s construction materials (A1–A3) are quantified and communicated, similar standards are needed to quantify the embodied carbon of infrastructure construction beyond the gate (A4-A5).
To address this gap, Alabama, Louisiana, Mississippi, and Virginia have joined a collaborative effort through the Federal Highway Administration’s (FHWA’s) Climate Challenge to conduct several case studies on the implementation of Life Cycle Assessment (LCA) for various pavement construction projects. This paper summarizes preliminary results from the various case studies. To encourage collaboration and harmonization amongst the state participants and beyond, OpenLCA was used to conduct the LCAs using the recommended public background datasets from the American Center for Life Cycle Assessment Open Standard, Federal LCA Commons, and the FHWA LCA Pave tool. The scope of the LCAs were cradle-to-construction (A1–A5). Construction practices included in the study are full depth reclamation with cement stabilization, hot mix asphalt with highly polymer modified binder, high recycled asphalt pavement with recycling agents and recycled plastics, and warm mix asphalt with lower mixing and compaction temperatures. Environment Product Declarations, where available, were collected from material manufacturers, while construction process data collected included water, fuel, materials used, transportation distances, and wastes or recycled materials hauled off-site.
Eugene Amarh, Ben Bowers, Sam Cooper III, Brian Diefenderfer, Heather Dylla, Gerardo Flintsch, Suri Gatiganti, Louay Mohammad, Nam Tran, Ibrahim Elnam
Life Cycle Assessment of Rubber Modified Asphalt Pavement in Michigan: A Case Study
Asphalt pavement is a critical component of modern infrastructure, and concerns about its environmental impact have arisen over the years. This paper presents a case study of rubberized asphalt pavement in Dickinson County, Michigan, employing a life cycle assessment (LCA) methodology. The objective of this study is to demonstrate the environmental benefits of rubber incorporation in road construction by scrutinizing the material, transportation, manufacturing and construction stages. By conducting data collection and analysis tailored to Dickinson County’s specific conditions, this research offers valuable insights into the environmental performance of rubberized asphalt pavement within a localized context. By comparing the environmental impact between a conventional asphalt section and a rubber pellet-modified pavement section, the findings emphasize the environmental advantages of utilizing recycled rubber in asphalt mixtures. The life cycle results demonstrate that rubber modified asphalt section produces lower greenhouse gas emissions and consumes less energy compared to conventional asphalt sections. These results underscore the significance of considering recycled materials, especially rubber products, in LCA studies.
Kai Xin, Dongzhao Jin, Robert M. Handler, Zhanping You
Life Cycle Assessment of Continuously Reinforced Concrete Pavement Overlay on Concrete Road Rehabilitation: Insights from Two Case Studies
In the realm of rehabilitating existing jointed plain concrete pavement (JPCP) or continuous reinforced concrete pavement (CRCP), the conventional choice is asphalt concrete (AC) overlays due to the cost-effectiveness of their initial construction and rapid traffic accessibility. However, AC overlays tend to deteriorate more quickly in structural performance and surface smoothness compared to the original JPCP or CRCP, necessitating more frequent post-overlay maintenance or rehabilitation. Recently, CRCP overlays have gained attention for outperforming AC overlays in terms of durability and ride quality. Despite their superior performance and lower use-phase cost, concerns linger regarding the overall environmental impact of CRCP overlays. To bridge the gap, this paper examines the sustainability of CRCP overlays through pavement life-cycle assessment (LCA). We conducted two case studies to evaluate the life-cycle environmental impacts, including both embodied and use-stage emissions of CRCP overlays for concrete pavement rehabilitation. We leveraged Pavement ME software for the prediction of pavement performance after rehabilitation and employed a streamlined pavement LCA framework to evaluate the life-cycle greenhouse gas (GHG) emissions of CRCP overlays. The results reveal that CRCP overlays tend to have higher embodied emissions, but much lower total GHG emission for a life-cycle perspective as compared to AC overlays. For the two case studies employed in this paper, the life-cycle GHG emissions for CRCP overlays can be as low as 15% of that of AC overlays for the rehabilitation of existing concrete pavements.
Haoran Li, Miaomiao Zhang, Hessam AzariJafari, Randolph Kirchain
Risk-Based Network-Level Pavement Treatment Optimization for Greenhouse Gas Emission Reduction
Transportation-related emissions are a major contributor to global greenhouse gas (GHG) emissions and are closely linked to pavement performance. Effective pavement treatment practices are crucial for sustaining pavement performance and mitigating associated GHG emissions. Although the treatment optimization for individual segments is well-studied, extending these strategies network-wide is challenging due to segment heterogeneity, budget constraints, and evolving performance across the network. This study introduces a novel risk-based framework for optimizing pavement treatments at the network level, aimed at reducing transportation-related GHG emissions within budgetary constraints. The framework is distinct in its integration of risk analysis, particularly Monte Carlo (MC) simulations and scenario analysis, to address uncertainties inherent in segment contexts and future treatment actions. This approach notably enhances the predictability of long-term impacts of treatments and the management of future uncertainties. The framework’s effectiveness was demonstrated through 50-year case studies on Colorado interstates. The integration of scenario analysis was pivotal in determining the optimal treatments for both individual segments and the entire network, leading to a notable reduction of 10% in network GHG emissions. This underscores the importance of considering long-term treatment impacts in promoting sustainable and resilient network management. Additionally, the application of MC simulations slightly raises the overall network GHG estimate but significantly reduces its variability, thereby enhancing the robustness of pavement network management.
Miaomiao Zhang, Haoran Li, Hessam AzariJafari, Randolph Kirchain
Towards the Assessment of Social Sustainability: Identifying Social Hotspots for Road Pavement Materials
Studies have focused on quantifying life cycle environmental and economic impacts of road pavement materials. However, social performance is often either assessed in a limited way (e.g., relying on qualitative indicators or checklists, not adopting a life cycle approach) or completely neglected, hindering a truly holistic sustainability assessment. Social life cycle assessment (S-LCA) has proven to be a powerful, science-based method for evaluating the social performance of materials and products with a life cycle perspective, addressing both negative and positive impacts. This contribution is a first step in analyzing the quantitative performance of the social impacts of road pavement materials via a social hotspot assessment. It was conducted using two tools: Product Social Impact Life Cycle Assessment (PSILCA) database and Social Hotspot Database (SHDB). A cradle-to-gate approach was adopted, focusing on raw material extraction and transport and the asphalt mixing process. Furthermore, the main contributing economic sectors related to asphalt pavement materials were defined. The social hotspot assessment identified the critical stakeholder categories, relevant social subcategories, and associated social risk indicators of the sectors related to asphalt production for the example of Lithuania. The obtained results provide new insights into the road construction industry and new hotspots to evaluate in the asphalt supply chain. In particular, the results provide guidance regarding which social issues have the most significant relevance and should be awarded priority when conducting an S-LCA of asphalt mixtures. Findings are key elements to support a comprehensive, quantitative, and holistic assessment of the sustainability of road infrastructure.
Pamela Del Rosario, Gabriella Buttitta, Davide Lo Presti, Marzia Traverso
Capital Goods Data in Asphalt Products
Asphalt use has astronomically increased since the 1900s, contributing to numerous environmental impacts. Among various archetypes, buildings and equipment stand out as significant contributors to capital goods and infrastructure environmental impacts in the asphalt value chain. In this work, we utilised the ecoinvent database, to analyse the impact of the inclusion and exclusion of capital goods in asphalt. The relative contribution of capital goods in asphalt to a suite of Life Cycle Impact Assessment (LCIA) indicators was estimated based on the types of capital goods available in ecoinvent. Results showed that transport infrastructure and energy infrastructure accounted for 4% and 21% of Land Use Impacts, respectively. However, we also that found that some inconsistencies in scope affected the accuracy of capital goods’ contribution. As Environmental Product Declarations (EPDs) rely on comparative data, an understanding of capital goods’ contribution will support improved and realistic data on capital goods in the LCIA of asphalt and its variants.
Olubukola O. Tokede, Supriya Mahlan, Rose Manakaa, Marzia Traverso
A Methodology for the Life Cycle Management of European Road Pavements
International and European standards are rapidly emerging to guide practitioners in achieving more consistent and precise sustainability assessments (SAs) across various sectors. In construction engineering, specific standards are developing, particularly in the building sector, while more questions persist for infrastructures. PavementLCM, a project funded by the Conference of European Directors of Roads, addressed this gap by aiding road authorities in designing and maintaining road pavements through life cycle thinking. The project, shaped through collaboration with industries and road authorities, establishes a framework for an SA specific to road pavements. This framework distinguishes between pavement materials and activities, offering indicators and best practices. The guidelines present a step-by-step procedure aligned with existing European standards for environmental building assessments (EN 17472:2022), aiming to establish a harmonized life cycle management approach for major road pavements in Europe. The authors’ goal is to support the implementation of sustainability assessments in Europe and inspire similar initiatives globally.
Davide Lo Presti, Ana Jimenez Del Barco Carrión, Gabriella Buttitta, Ali Azhar Butt, John Harvey
A Systematic Digitalization for Climate Mitigation and Adaptation Measures in Long-Term Road Planning
Facing the growing challenges posed by climate change, the importance of integrating climate mitigation and adaptation measures in long-term road planning has become increasingly crucial. From road design involving different materials and constructions to maintenance planning and material circularity, an integral assessment is critical for infrastructure management, as decisions made today will have far-reaching implications for the future. This paper underscores the pressing need for systematic digitalization in road planning, augmented by life cycle assessment (LCA), and the key benefits of leveraging materials knowledge in this process. Systematic digitalization offered by ORIS Materials Intelligence involves the data collection, analysis, and usage of various datasets regarding materials, climate, and traffic towards environmental and social parameters, to enable more informed decision-making. Advanced modeling, automatic simulation techniques, and effective visualizations allow planners to evaluate climate exposures, as well as network vulnerability, and craft climate adaptation strategies for enhanced resilience. Moreover, the emergence of such digital capabilities offers a unique opportunity to systematically and consistently assess alternative designs and deliver low impact infrastructure by connecting local materials data with engineering expertise to simulate the cost and carbon performance through a road’s life cycle. The LCA model also predicts the impact from pavement-vehicle interactions and the effect of albedo and carbonation, which enables an inclusive decision-making process through a whole value chain. Recent studies have resulted in up to a 30% reduction in cost, 50% in carbon and 80% in resource utilization.
Koji Negishi, Léa Fishcer, Renaud De Montaignac
A Graphene-Enhanced Recycled-Plastic Asphalt Mixture Modifier: Two Case Studies in the United Kingdom and the United States of America
In addition to heavy and frequent traffic loads, climatic conditions pose significant challenges for asphalt pavement designers. The situation becomes even more challenging in areas with high average temperatures and extreme climates, greatly affecting design parameters. This paper introduces an innovative asphalt mixture modifier made from carefully selected recycled plastics and graphene nanomaterial, which has been trialled in both the United Kingdom and the United States of America. This modifier, applied through a dry method/process, enables the production of a high-performance asphalt mixture, especially suitable for areas with heavy traffic loads or those located in hot climate regions. From the environmental perspective, the resultant product exhibits a remarkably low embodied carbon, as demonstrated in the corresponding Environmental Product Declaration (EPD), making it a sustainable alternative to other common asphalt modifiers. The test results presented in this paper reveal that asphalt mixtures with this modifier exhibit a higher modulus, increased strength, superior resistance to permanent deformation, comparable or better fatigue performance, and improved low-temperature performance when compared to their counterpart reference asphalt mixtures. In addition to its environmental benefits, this asphalt modifier has been rigorously examined and monitored in numerous projects over the past few years. It has been successfully employed in many large-scale projects both in Europe and the United States of America. Most recently, the Virginia Department of Transportation placed a field trial featuring the use of this asphalt modifier as part of their ongoing effort to evaluate “Sustainable Surface Mixtures Incorporating Recycled Plastic Waste.”
Bob Allen, Stacey Diefenderfer, Jhony Habbouche, Loretta Venturini, Shahin Eskandarsefat
Toward Sustainability – Life Cycle Perspective in Green Hydrogen and By-Products Material in Asphalt Production: A Case Study for Road Pavement
The consensus on reducing Greenhouse Gas (GHG) emissions and promoting sustainable practices in the energy sector is strong. The Sustainability Development Goals (SDGs), particularly SDG 13 and SDG 12, explicitly refer to the 2015 Parsi Agreement, and emphasize limiting and keeping global warming to a maximum of 1.5 ℃ and advocating for sustainable production and consumption. Meeting global energy demand requires large-scale infrastructure and storage, with growing interest in hydrogen as a sustainable energy carrier. To that end, establishing global hydrogen networks is crucial for a swift transition. Decision-making processes should incorporate comprehensive life-cycle analyses (LCAs) to support this transition effectively. This paper conducts LCAs according to the ISO 14040/44 methodology for road pavement using Crumb Rubber (CR) and Electric Arc Furnace (EAF) slag as materials, along with alternative fuels for asphalt production. The findings of the study reveal that while fossil fuels may be more economically viable, the adoption of cleaner alternatives, such as green hydrogen and green electricity, can significantly mitigate global warming impacts, with a potential reduction of up to 70%. This highlights the importance of considering low environmental-impacting fuel alternatives in asphalt production road construction and industry to combat Global Warming Potential (GWP).
Manouchehr Shokri, Rose Nangah Mankaa, Marzia Traverso
Pavement, Roadway, and Bridge Life Cycle Assessment 2024
Gerardo W. Flintsch
Eugene A. Amarh
John Harvey
Imad L. Al-Qadi
Hasan Ozer
Davide Lo Presti
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