Effects of C-S-H seeding dosages on the calorimetry and phase assemblage of cement hydration

The influences of varying dosages of C-S-H seeding on the properties of cement were assessed through a variety of methodologies. Calorimetry results revealed that the presence of C-S-H seeding notably reduces the induction period and enhances the total heat release during the initial days of cement hydration. All of the systems studied followed similar hydration kinetics, encompassing nucleation and growth (NG), phase boundary reaction (I) and diffusion (D). As the dosage of C-S-H seeding increased, there was a quicker transition from NG to I to D. XRD-Rietveld analysis indicated that seeding markedly improves alite and C3A dissolution in the early stages of hydration, ultimately leading to the expeditious precipitation of portlandite (CH) and ettringite. Nonetheless, at later hydration stages, higher dosage of C-S-H seeding compromises the alite reaction, resulting in a decreased amount of portlandite in the system. The CH obtained by thermogravimetry exhibited a similar trend to XRD-Rietveld, signifying their reliability in measuring portlandite content in the hydrated cement paste.