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

Based on the analytical H-1 low-field nuclear magnetic resonance (NMR) technique, we developed a novel method and corresponding model to analyze the hydration degree (alpha(t)) of cement in cement paste under different curing conditions. The hydration degree can be calculated quantitatively based on the transverse relaxation time (T-2) distributions using NMR measurements. The T-2 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 degrees C and steam curing at 60 degrees C were obtained. The alpha(t) of cement was studied by the hydration heat method and portlandite (CH) quantitative measurements. The results show that the intensity-weighted T-2 value of non-surface water peaks ((T) over bar (2)) has a significant correlation with alpha(t) 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.

Automated summary

A novel method and model have been developed to analyze the hydration degree of cement paste using the analytical H-1 low-field NMR technique. The hydration degree can be quantitatively calculated based on T-2 distributions, with significant correlations found between T-2 values and hydration degree under different curing conditions.