Exploring the feasibility of using recycled fines from diverse sources as partial cement substitutes in high-performance cementitious materials

• Recycled fines from different sources are investigated and used as secondary raw materials in concrete and compared to commercial SCMs. • A life cycle analysis multiperformance criterion is defined as a decision making tool. • The use of recycled fines in UHPC production is proposed. • Fresh and hardened state performance are assessed. Advancing sustainable construction requires the development of durable materials while extending the life of end-of-life resources traditionally considered as waste. Construction and demolition waste represents a rapidly growing stream requiring effective recycling and valorisation strategies. Current directives promote the use of secondary raw materials to reduce environmental impacts and conserve natural resources. This study aims to reduce the environmental footprint of cementitious materials by repurposing fine fractions derived from diverse waste streams, including construction and demolition waste, recycled concrete, brick debris, and glass, as partial cement replacements in high-performance cement-based composites. A multi-scale experimental approach was adopted, starting with mortar mixtures to evaluate fresh properties, mechanical performance, and environmental behaviour, and subsequently extended to ultra-high-performance concrete formulations. Optimized ultra-high-performance concrete formulations achieved reduced cement content while maintaining superior performance and minimizing environmental impact. Results demonstrate that recycled fines can shift from disposal burdens to valuable resources, supporting circular-economy principles and enabling next-generation sustainable cementitious composites with enhanced technical performance and reduced environmental footprint.