Effect of nanosilica and silica fume on supersulfated cement properties and hydration

The article provides a comparative analysis of the hydration effects of nanosilica (NS) and silica fume (SF) in supersulfated cement, investigating the reasons for the differences between their effects. The effects of the addition of 3% NS and SF on the macroscopic and microscopic properties of supersulfated cement were studied. The experimental results show that the compressive strength of NS group is lower than that of SF group in low-clinker samples, while in high-clinker samples, presenting an opposite trend, and NS and SF can sustainably increase the compressive strength, and the long-term effect is more evident. In addition, both NS and SF can reduce the hydration heat due to hindering the formation of ettringite, and the inhibitory effect of NS is greater than that of SF. Moreover, NS will significantly decrease the pH value and saturation index, and drastically reduce the concentration of calcium ion, while SF has no obvious effect on this. This study highlights that NS is more suitable for high-clinker SSC systems (e.g., structural engineering requiring long-term strength), while SF performs better in low-clinker systems (e.g., eco-friendly pavements), providing a theoretical basis for material selection in practical engineering.