Evolution of the particle size distribution of tricalcium silicate during hydration by synchrotron X-ray nano-tomography

The particle size distribution of tricalcium silicate (C3S) is essential for the modelling of early C3S hydration kinetics. In this study, this parameter is analysed during the main hydration period until the first 20 h by synchrotron near-field ptychographic (NF-PXCT) and holographic (HXCT) computed nano-tomography. Additionally, X-ray diffraction, 29Si NMR, thermal analysis, scanning electron microscopy, and inductively coupled plasma-optical emission spectroscopy were used to investigate the system evolution. The time-dependent pore solution composition is also provided to gain further information. HXCT and NF-PXCT show comparable values regarding the evolution of the C3S particle size distribution during hydration, indicating that C3S particles smaller than 1.3 μm are completely dissolved after 20 h of hydration. The results can be reasonably reproduced by numerical models if for all particle sizes a constant reacted rim thickness for each degree of hydration is assumed. Data on the aqueous phase composition are also provided.