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 o f hydration of tricalcium silicate using the H-1(N-15,alpha gamma)C-12 reac tion. The surface layer had an H concentration and thickness consistent wit h a few unit cells (1.1 nm) of tobermorite-like material. The inner regions exhibited diffusion-controlled growth with time until the hydrogen concent ration 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.