A novel approach for high-efficient activation of large-volume slag cement towards a lower-carbon future in cement industry

Substituting ordinary Portland cement (OPC) with supplementary cementitious materials (SCMs) is a widely adopted strategy in the cement industry to reduce CO2 emissions. However, the low reactivity of SCMs often results in delayed early strength development when used in large quantities. This study aims to substitute 70 % of OPC with ground granulated blast furnace slag (GGBFS) and efficiently activate this system through calciumferrite-silicate-hydrates/polycarboxylate ether (C-F-S-H/PCE) nanocomposites and sodium sulfate. The findings indicate that the combined use of both activators has a significant positive effect on the strength development of this low-carbon cement, demonstrating comparable performance to OPC without any substitution. This can be attributed to the effective enhancement of the reactivity of the low-carbon cement, particularly GGBFS. Furthermore, the utilization of C-F-S-H/PCE nanocomposites improves the polymerization degree and leads to a more compact morphology of the calcium-aluminum-silicate-hydrates (C-A-S-H) gel without affecting the Al/Si. The proposed activation approach provides a foundation for the large-volume utilization of GGBFS and other SCMs in cement-based materials and holds enormous potential for reducing CO2 emissions in cement industry.