A novel method for semi-quantitative analysis of hydration degree of cement by 1H low-field NMR

Based on the analytical 1H low-field nuclear magnetic resonance (NMR) technique, we developed a novel method and corresponding model to analyze the hydration degree (αt) of cement in cement paste under different curing conditions. The hydration degree can be calculated quantitatively based on the transverse relaxation time (T2) distributions using NMR measurements. The T2 distributions of the cement paste samples with the water/cement (W/C) ratios of 0.25, 0.35 and 0.45 under standard curing, steam curing at 40 °C and steam curing at 60 °C were obtained. The αt of cement was studied by the hydration heat method and portlandite (CH) quantitative measurements. The results show that the intensity-weighted T2 value of non-surface water peaks ( T 2 ¯ ) has a significant correlation with αt that can be expressed by an exponential equation. In this paper, the derivation of this exponential equation is given, and the effects of W/C ratio and curing condition on its parameters are analyzed.