Advancing sustainable construction: exploring the role of sintering in enhancing alkali-activated and cement concrete

This review paper critically examines the role of sintering techniques both conventional and cold in enhancing the performance of cement-based and alkali-activated concrete (AAC) systems, with a focus on their potential for sustainable construction. Sintering, a thermal process traditionally used in ceramics and powder metallurgy, has emerged as a promising method in concrete technology to improve microstructural densification, reduce porosity, and enhance mechanical properties. In the context of cement concrete, recent advancements in cold sintering carried out at low temperatures (< 200 °C) and moderate pressures (100–200 MPa) have shown an average compressive strength improvement of 20–35%, indicating its feasibility for energy-efficient and sustainable precast construction. For alkali-activated materials, hot and warm pressing techniques under varying thermal and pressure conditions have resulted in significant improvements in compressive strength and durability. Studies report strength enhancements of up to 134 MPa for fly ash-based geopolymers and even much more in silica fume-enhanced composites under controlled hot pressing. The review synthesizes findings on key process variables—including temperature, pressure, dwell time, and material composition, which influence sintering efficacy. Furthermore, the paper explores the microstructural transformations, densification mechanisms, and environmental benefits associated with sintering. Special emphasis is given to the application of sintering in utilizing industrial waste materials and promoting low-carbon construction technologies. This review consolidates current research trends and identifies critical knowledge gaps, providing a comprehensive foundation for future investigations into sintering-based concrete processing for high-performance and sustainable infrastructure. Its integration into sustainable construction projects—such as modular precast systems, pavement blocks, façade panels, and structural elements can significantly advance the development of durable and environmentally responsible infrastructure.