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Ascertaining the Environmental Advantages of Pavement Designs Incorporating Recycled Content through a Parametric and
Zhaoxing Wang1, Joao Santos2, Chunli Chu3
1Sustainable Pavements and Asphalt Research (SuPAR), Faculty of Applied Engineering, University of Antwerp, 2020 Antwerp, Belgium.
Environmental Science & Technology
|January 24, 2025
Summary
Using reclaimed asphalt pavement (RAP) in thicker layers doesn't always lower construction greenhouse gas (GHG) emissions. However, considering the use phase, fuel savings can reduce overall GHG emissions, emphasizing the importance of this phase in pavement life cycle assessment (LCA).
Area of Science:
- Civil Engineering
- Environmental Science
- Materials Science
Background:
- Reclaimed asphalt pavement (RAP) is crucial for circular economy in asphalt pavements.
- Increased RAP use can necessitate thicker layers, potentially increasing material, energy, and transport demands.
- Existing life cycle assessments (LCAs) may not fully capture the complex interplay of factors in pavement design with recycled materials.
Purpose of the Study:
- To develop a robust parametric and probabilistic life cycle assessment (LCA) framework for comparing pavement designs with recycled materials.
- To reveal the intricate relationships between design parameters and environmental impacts.
- To provide a nuanced understanding for decision-making in sustainable pavement engineering.
Main Methods:
- Developed a parametric and probabilistic LCA framework based on thermodynamic and physical principles.
- Integrated Mechanistic-Empirical Pavement Design Guide (MEPDG) and Highway Development Management (HDM4) models for use-phase impact estimation.
- Employed pedigree approach and Monte Carlo simulation to address data uncertainty.
Main Results:
- Evaluated 66 Flemish motorway segments using the developed LCA framework.
- Found that thicker RAP layers do not guarantee lower construction greenhouse gas (GHG) emissions.
- Demonstrated that use-phase fuel savings can lead to lower overall GHG emissions, underscoring the significance of the use phase in pavement LCA.
- Identified key contributors to GHG emissions variance, including fuel consumption, transport distances, fine aggregate mass, and construction machine parameters.
Conclusions:
- The developed LCA framework offers a comprehensive approach to comparing pavement designs with recycled content.
- Parametric and probabilistic analysis enhances the robustness of LCA results, enabling better decision-making.
- Reducing uncertainty in key parameters like fuel consumption and transport can significantly improve the clarity and reliability of pavement LCA.
- The study highlights the critical importance of considering the entire pavement life cycle, particularly the use phase, for accurate environmental impact assessment.
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