Synergistic effects of high-volume cement replacement in binary, ternary, and quaternary binder systems

To achieve 2050 carbon neutrality amidst rising infrastructure demand, transitioning to high-volume supplementary cementitious material (SCM) replacement is an industrial necessity. This study investigates the fresh, mechanical, microstructural, and durability performance of thirteen binary, ternary, and quaternary binder systems containing up to 75% cement replacement with combinations of slag (S), fly ash (FA), metakaolin (MK), and silica fume (SF) - evaluating workability, compressive strength, shrinkage, sorptivity, and sulfate resistance, supported by SEM analysis. Results indicate that 25PC-50FA-25S exhibited the best fresh properties, while 50PC-50S achieved the highest 90-day strength (55 MPa). However, 25PC-50S-12.5MK-12.5SF emerged as the optimal sustainable structural binder, achieving 90-day strength exceeding 36 MPa and demonstrating superior durability, with negligible drying shrinkage and exceptional resistance to sulfate attack (net shrinkage) over 12 weeks. This research confirms that tailored binder systems can produce resilient, structural-grade mortars with up to 75% reduction in cement content, offering a viable pathway for sustainable infrastructure.