Effect of the nanosilica source on the rheology and early-age hydration of calcium sulfoaluminate cement pastes

This work investigates the role of different nanosilica (NS) sources on the rheology and early-age hydration of calcium sulfoaluminate (CSA) cement paste. Specifically, pastes were produced with three NS (two powder and one colloidal suspension) in 1 wt% replacement of cement, with and without superplasticizer. Rotational rhe-ometry, isothermal calorimetry, and in-situ X-ray diffraction (XRD) tests were conducted. The results showed that incorporation NS increased the yield while decreased the viscosity and delayed the shear thickening onset point of CSA pastes, regardless of the NS source. Calorimetry and in-situ XRD revealed that NS incorporation enhanced the CSA cement hydration kinetics while superplasticizer delayed it. Overall, colloidal NS led to the best overall early-age performance, leading to the lowest viscosity and the highest hydration degree over time among the CSA cement pastes investigated.

Automated summary

This study investigates the impact of different nanosilica sources on the rheology and early-age hydration of calcium sulfoaluminate cement paste. The results show that the addition of nanosilica increases the yield, decreases the viscosity, and delays the shear thickening onset of the paste. Colloidal nanosilica leads to the best early-age performance, with the lowest viscosity and highest hydration degree over time among the investigated cement pastes.