Quantifying early age hydration and micro-structure evolution of fast setting binder using 1H NMR

The first hours’ hydration of fast-setting binder is difficult to monitor due to the limited temporal resolution of common micro-structure-chemistry probes and the complicated product compositions. This study explored using T₂ relaxation time distribution data from in-situ ¹H nuclear magnetic resonance (NMR) measurement to quantify the early-hydration kinetics of two OPC/CAC/calcium sulfate ternary binders. The calculated phased composition and porosity evolution were compared with evidence from in-situ XRD, SEM, TGA, temperature and tensile splitting strength evolution. We demonstrate that the deconvoluted T₂ signal of water can provide a reliable estimation of microstructural information, e.g., the ettringite product and the porosity. There exists a linear relationship between the averaged T₂ signal and the porosity of the paste. In addition, the averaged T₂ signal provides a good index of strength, which applies equally to all studied samples despite their different in the cement type, w/c and presence of fine aggregates.