Comparative Analysis of Sustainable Materials in Urban Pavement Construction

Thesis Abstract

The rapid urbanization and increasing environmental concerns necessitate the exploration and implementation of sustainable materials in urban pavement construction to mitigate ecological impacts and promote long-term infrastructural resilience. This study aims to conduct a comprehensive comparative analysis of proposed sustainable materials—specifically recycled asphalt pavement (RAP), geopolymer concrete, and bio-based binders—evaluating their mechanical performance, environmental footprint, economic viability, and durability within urban contexts. The primary objectives include identifying the performance characteristics of each material, quantifying their environmental impacts using life cycle assessment (LCA), and assessing cost-effectiveness through detailed financial analysis. The research adopts a mixed-methods approach, integrating quantitative laboratory-based experimental assessments with qualitative evaluations. The quantitative component involves testing collected samples of each material type, sourced from five distinct urban construction sites across the metropolitan area, with a total sample size of 150 specimens (30 per material type). Laboratory procedures include standardized tests such as compression strength tests, permeability assessments, and durability examinations under accelerated aging conditions. The environmental impact is quantified via LCA following ISO 14040/44 standards, providing a comparative footprint analysis. The qualitative aspect involves semi-structured interviews with twenty-five civil engineering practitioners and policymakers to capture insights on material acceptability, regulatory challenges, and operational considerations. Data analysis involves applying statistical techniques such as Analysis of Variance (ANOVA) to compare performance metrics across materials, multiple regression analysis to identify key factors influencing durability and cost-efficiency, and thematic analysis of interview transcripts to interpret practitioner perspectives. The theoretical framework underpinning the study draws upon the Sustainable Development Theory and the Life Cycle Sustainability Assessment (LCSA), guiding holistic evaluations of environmental, economic, and social dimensions of each material. Expected findings anticipate that geopolymer concrete will demonstrate superior durability and lower carbon emissions compared to traditional asphalt, while bio-based binders might exhibit comparable mechanical strength but higher costs. Recycled asphalt pavement is expected to offer significant environmental benefits with moderate performance characteristics, thus presenting a viable sustainable alternative with potential trade-offs. The study will elucidate the conditions under which each material type is most advantageous, highlighting their respective strengths and limitations. The contribution of this research lies in bridging knowledge gaps concerning the comparative sustainability of innovative urban pavement materials; notably, the integration of environmental, economic, and performance data provides a comprehensive decision-making framework for practitioners and policymakers. The empirical evaluations and stakeholder insights will inform guidelines for sustainable pavement material selection, fostering environmentally responsible urban infrastructure development. Main conclusions suggest that geopolymer concretes are promising sustainable alternatives for high-traffic urban roads, whereas recycled asphalt remains feasible for low to moderate traffic areas, with bio-based binders requiring further cost reductions to be widely adopted. The study recommends prioritizing geopolymer adoption in city planning, encouraging policy incentives for recycled materials, and supporting further research into cost-effective bio-based solutions. Additionally, it advocates for standardization efforts in the certification of sustainable pavement materials and emphasizes the importance of integrating environmental assessments into routine construction practices to promote sustainable urban development. Recommendations for future research include long-term field performance studies and exploring hybrid material formulations to optimize sustainability metrics across diverse urban contexts.