Study of cement chemistry with nuclear resonant reaction analysis

Abstract

Nuclear Resonance Reaction Analysis (NRRA) 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, the major constituent of Portland cement. To obtain the best spatial resolution, it is necessary to have good beam energy resolution. Three regions were observed in the profile, whose H concentrations were obtained by using the 1H(15N,αγ)12C reaction. By analogy with the hydration of alkali silica glasses, these are identified as the reaction-controlling surface layer, the gel layer, and the calcium-leached layer. The surface layer has an H concentration and thickness consistent with a few unit cells (1.1 nm) of tobermorite-like material. The inner regions exhibit diffusion-controlled growth with time until the hydrogen concentration approaches that of the surface layer at 4.25±0.07 hrs. This event marks the end of the induction period.