GGBS hydration acceleration evidence in supersulfated cement by nanoSiO2

Supersulfated cement (SSC) is a potential low-carbon cementitious binder, but its sluggish property-gain feature owing to GGBS's weak reactivity has significantly limited its application. For the first time, the dissolution of GGBS and the precipitation of hydrates in SSC are controlled by the unique physicochemical features of nanoSiO(2) (NS). SSC's hydration and hardening properties with 0%-3% NS were systematically investigated. The results showed that NS enhances the strength of SSC at both early and late ages, and the strength of SSC mortar can be doubled by 3% NS at 90 days. It continuously increases the reaction rate of SSC, resulting in a rise in the gel phase content, a decrease in gypsum consumption, and a reduction in the formation of ettringite of varying morphology. NS increases the reaction degree of GGBS, forming more C-(A)-S-H gel and significantly compacting the microstructure of SSC. The controlling variables leading to the continuous growth of macro-property gain of SSC have been identified as the reduction of calcium ions in SSC by NS and the concomitant enhancement of GGBS dissolution. This work demonstrated a viable method of dealing with issues related to the production and utilization of SSC.