A Framework for Sustainable Concrete Mix Design Using Recycled Industrial Byproducts

Thesis Abstract

The escalating environmental impacts of traditional concrete production, coupled with the depletion of natural raw materials, necessitate the development of sustainable construction materials that minimize ecological footprints while maintaining structural performance. This study addresses the critical challenge of integrating recycled industrial byproducts into concrete mix designs to promote sustainability without compromising quality. The primary aim is to develop a comprehensive framework that guides the optimal utilization of these byproducts—such as fly ash, ground granulated blast furnace slag, and recycled construction and demolition waste—in concrete manufacturing processes. Specific objectives include evaluating the mechanical, durability, and sustainability performance of concrete mixes incorporating recycled byproducts, formulating a standardized mix design procedure, and establishing decision rules grounded in environmental and engineering performance criteria. The research employs a mixed-methods approach, combining experimental laboratory investigations with analytical modeling. A quantitative experimental design was adopted, involving the production and testing of 150 concrete samples with varying proportions of recycled industrial byproducts based on a factorial arrangement. The study population comprises concrete mixes formulated with different percentages (10%, 20%, 30%, and 40%) of recycled materials, prepared according to ASTM standards. Data collection instruments include standardized compressive strength tests, water absorption tests, permeability assessments, and lifecycle assessment (LCA) metrics utilizing a recognized environmental software tool. Mechanical properties were analyzed through ANOVA to determine the significance of varying proportions, while multi-criteria decision analysis (MCDA) techniques, such as TOPSIS, were employed to rank mix options based on performance trade-offs. Key expected findings include the identification of optimal ratios of recycled byproducts that meet or exceed minimum performance standards for strength, durability, and environmental impact. It is anticipated that mixes with 20-30% recycled materials will demonstrate comparable compressive strength to conventional concrete while significantly reducing embodied energy and carbon dioxide emissions. The study aims to establish statistically validated correlations between recycled material proportions and mechanical properties via regression analysis, offering predictive models adaptable to different contexts. Results are expected to reveal that specific combinations of fly ash and recycled aggregates positively influence durability parameters, such as permeability and resistance to chemical attack. This research contributes novel insights into sustainable concrete design by integrating environmental and engineering performance metrics into a unified decision-making framework. The development of a standardizable, evidence-based mix design procedure grounded in empirical data and validated analytical models aims to fill prevailing gaps related to the practical application of recycled byproducts in concrete. The theoretical underpinning is rooted in the Theory of Planned Behavior and Sustainable Development Frameworks, emphasizing stakeholder influence and environmental stewardship. The study concludes that the proposed framework substantially advances sustainable construction practices and provides industry stakeholders with robust guidelines to implement recycled industrial byproducts effectively. Recommendations include formulating standardized policies to incentivize the use of recycled materials and further exploring long-term durability performance through field studies. Future research should extend this framework to encompass emerging industrial byproducts and examine lifecycle cost analyses to promote widespread adoption. Overall, this work paves the way for more sustainable, resource-efficient concrete production, aligning engineering innovation with environmental conservation imperatives.