Characterization of the induction period in tricalcium silicate hydration by nuclear resonance reaction analysis

Nuclear resonance reaction analysis has been applied for the first time to measure the development of the hydrogen depth profile in the early stages of hydration of tricalcium silicate using the ¹H(¹⁵N,αγ)¹²C reaction. The surface layer had an H concentration and thickness consistent with a few unit cells (1.1 nm) of tobermorite-like material. The inner regions exhibited diffusion-controlled growth with time until the hydrogen concentration approaches that of the surface layer at 4.25 ± 0.07 h. This event marked the end of the induction period and the onset of the rapid hydration reaction period.