Reutilization of steel slag (SS) in super sulfate cement (SSC): A comparative study of SS dosage and carbonation treatment on strength development, hydration behavior and sustainable development

Abstract

The development of low-carbon cementitious materials is one of the important ways to alleviate the problem of large accumulation of industrial by-products and reduce high energy consumption and high carbon emissions in the cement industry. This study investigated the possibility of using steel slag (SS) as an alkaline activator to prepare super sulfate cement (SSC). The hydration reaction test (hydration heat and pH value) and microscopic characterization (XRD, FTIR, TG and SEM) were used to systematically study the influence mechanism of SS dosage and its carbonation treatment on the macroscopic mechanical properties of the samples. The results show that SS has excellent carbonation reaction activity, and the degree of carbonation increase within 24 h reaches 10.71 %. Under the action of 6 wt% SS or 15 wt% carbonated steel slag (CS), the hydration degree of ground granulated blast-furnace slag (GGBS) was improved, the content of hydration products such as ettringite (AFt) was significantly increased, the crystal structure was improved (grain size, polymerization degree and Ca/Si ratio), and the pore structure of the matrix was more compact. Compared with ordinary Portland cement (OPC) and SSC, the CO₂ emissions and production costs of NUS and NCS samples are significantly reduced. These insights provide a potential possibility for the scale utilization of SS, which is conducive to promoting the green transformation and development of the construction industry.