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Sustainability Assessment of Perpetual Pavements Using Mechanistic-Empirical Approach

Sadeghi, Mehdi | 2022

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 55035 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Tabatabaee, Nader; Sabouri, Mohammad Reza
  7. Abstract:
  8. Pavements are essential part of transportation infrastructures that are expensive to build and maintain and could significantly affect the environment. In recent decades, global warming has become a major concern. Therefore, in pavement design in addition to the economic and environmental considerations, conformity with sustainable development have received attention. In the past decades in Iran, because of the low production and high price of cement, and availability of inexpensive bitumen, flexible pavements were the predominant type. However, the increased price of bitumen in the past two decades has changed the balance of the highway construction projects, and bitumen procurement has absorbed more than half of project funds. Also, with the decline in dam constructions, there is surplus capacity of cement production in Iran. Therefore, construction of concrete pavements is on the rise.This study evaluates sustainable pavement design alternatives by integrating the mechanistic-empirical (ME) design procedures, life cycle cost analysis, life cycle assessment, and multi-criteria decision analysis (MCDA) methods. In this study, four pavement design alternatives, including conventional flexible, perpetual, composite, and semi-rigid, were designed using the MEPDG software for three traffic levels in four climate regions. Based on the AADTT of Iran's highways, three traffic levels, including high, medium, and low, were considered. Four climatic regions of dry no-freeze, dry freeze, wet no-freeze, and wet freeze, were considered. Perpetual, semi-rigid, and composite pavements are long-life design alternatives with a minimum design life of 50 years. Each pavement alternative was designed and evaluated for 50 years, including the initial structure and several rehabilitations throughout its life cycle. The MEPDG performance criteria thresholds were used to schedule rehabilitation activities. The sustainability assessment methods of LCA and LCCA were implemented to evaluate the environmental and economic benefits of design alternatives. Finally, pavement design alternatives were ranked in each traffic category using the multi-criteria decision analysis methods.This study demonstrated that the conventional flexible and perpetual pavements were more sustainable for low and high traffic categories, respectively. For the medium-traffic, conventional flexible pavements were more sustainable considering Iran's high discount rate, but perpetual pavements were preferred where the economy is more stable. Despite having the lowest net present value among all alternatives for high and medium traffic roads, composite pavements were not the most sustainable option because their high carbon footprint offset their economic benefits
  9. Keywords:
  10. Life Cycle Assessment ; Stability ; Asphalt Pavement ; Life Cycle Cost (LCC) ; Mechanistic Empirical Pavement Design Guide (MEPDG)Method ; Perpetual Pavements

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