Comparative Analysis of Sustainable Concrete Mixes in Urban Infrastructure Projects

Thesis Abstract

The increasing demand for sustainable urban development necessitates the evaluation and implementation of environmentally friendly construction materials, with concrete being a pivotal component in infrastructure projects. Traditional concrete formulations, while durable, contribute significantly to carbon emissions and resource depletion; hence, the urgent need to identify and compare alternative sustainable concrete mixes that can effectively balance structural performance and environmental impact. This study aims to conduct a comprehensive comparative analysis of innovative sustainable concrete mixes utilized in urban infrastructure projects, focusing on their mechanical properties, durability, environmental footprints, and cost-effectiveness. The specific objectives include evaluating the compressive strength, tensile strength, and workability of different sustainable concrete formulations; assessing their environmental impacts through life cycle assessment (LCA); analyzing economic feasibility; and identifying optimal mixes for large-scale urban application. The research adopts a mixed-methods research design combining quantitative laboratory experiments with qualitative technical insights. The population for this study comprises sustainable concrete mixes documented in recent scholarly and industrial reports, targeted at urban construction projects within metropolitan settings. A stratified random sampling technique was employed to select twelve concrete formulations—six utilizing supplementary cementitious materials (SCMs) such as fly ash, slag, and silica fume, and six incorporating recycled aggregates and bio-based admixtures—based on relevance, innovation, and previous application hints. The sample size consisted of 144 concrete specimens, with twelve replicates per mix formulation, tested for compressive strength, splitting tensile strength, and slump workability. Data collection was conducted using standardized testing procedures conforming to ASTM and EN standards for mechanical properties and durability assessments. Environmental impact data were gathered via detailed life cycle assessment methodology, employing the ReCiPe impact assessment framework to quantify ecological footprints such as carbon footprint, water usage, and resource depletion. Cost analysis incorporated material and processing expenses gathered through supplier records and project budgets. The reliability and validity of laboratory procedures were ensured through calibration, control tests, and peer validation. Data analysis employed statistical tools including Analysis of Variance (ANOVA) to compare mechanical and durability parameters across mixes, regression analysis to identify relationships between mix components and performance indicators, and thematic analysis of qualitative insights into practical considerations. Expected findings anticipate statistically significant differences in mechanical strengths, durability performance, and environmental impacts among the selected concrete mixes. It is hypothesized that mixes incorporating higher proportions of SCMs and recycled materials will demonstrate comparable or superior strength and durability metrics relative to conventional concrete, while also exhibiting reduced ecological footprints. Furthermore, economic analysis is projected to reveal cost advantages for mixes that utilize industrial by-products and recycled aggregates, rendering them feasible for large-scale urban deployment. The contribution to knowledge lies in providing an empirically grounded, comprehensive framework for selecting sustainable concrete mixes tailored for urban infrastructure, integrating environmental, mechanical, and economic criteria. This integrated approach advances perspectives on sustainable construction practices by establishing evidence-based guidelines and decision-making tools for policymakers, engineers, and urban planners. The main conclusion underscores the viability of specific sustainable concrete formulations as environmentally responsible alternatives in urban infrastructure projects, emphasizing the importance of tailored mix design to optimize performance and sustainability objectives. Recommendations derived from this study advocate for standardization of sustainable concrete formulations, incentives for adopting recycled materials, and further research into long-term performance monitoring under real-world conditions. Future studies should explore the performance of these mixes over extended service life and under varying climatic conditions, alongside integrating digital modeling techniques to refine sustainability assessments. This research thereby contributes critical insights toward fostering more sustainable, resilient, and cost-effective urban infrastructure development globally.