Resource efficiency and sustainability of carbonated steel slag -cement with sodium salicylate

Carbonated steel slag (SS) powder offers potential for enhancing reactivity and sequestering CO₂, yet its hydration reactivity remains suboptimal. This study introduces sodium salicylate as a novel additive to systematically investigate its synergistic effects with carbonated SS-cement on hydration behavior, mechanical properties, and microstructure, aiming to uncover the scientific basis and application potential of this innovative mechanism. The results showed that sodium salicylate significantly improved the process of hydration in carbonated SS-cement, improved mineral dissolution and supported the development of key hydration products (Mc and C-S-H). Additionally, sodium salicylate refined the structure of pores in carbonated SS-cement, reducing porosity and increasing microstructural density. At 28 days, replacing 30 % cement with highly carbonated SS and adding 0.2 wt% sodium salicylate resulted in a compressive strength of 46.9 MPa, a 29.6 % increase over samples without sodium salicylate and comparable to pure OPC. This study indicated that sodium salicylate was a cost-effective and efficient additive that significantly improved the performance of carbonated SS-cements, offering new insights into the application of carbonated SS as a supplementary cementitious material.