Structural Studies of Hydrated Tricalcium Silicate by Neutron Powder Diffraction

Abstract

Structure refinements have been carried out on the pure tricalcium silicate (C₃S) and the hydrated C₃S with the D₂O–C₃S mass ratio, which is 0.5, using neutron powder diffraction (NPD). The multi-phase Rietveld analysis of the hydrated C₃S revealed the coexistence with the Ca(OD)₂ (trigonal phase) and the unhydrated C₃S (triclinic one). The Ca(OD)₂ phase was hardly observed on the NPD patterns in the first ∼6 h of hydration, while the several Bragg reflections of Ca(OD)₂ appeared drastically from ∼6 to ∼24 h, and then the hydration reaction rate was gradually suppressed. We could apply the Avrami-model to the initial hydration reaction process of C₃S.