Cement hydration kinetics followed by electron spin resonance

Cement hydration is driven by a complex system of chemical reactions of several hydraulic binders and water that influence each other. Here we establish a method to measure the hydration kinetics of an individual clinker phase by electron spin resonance spectroscopy. The hydration of a Mn(II) doped crystalline phase can be analyzed from the decay of signals coming from the starting material and the formed product. Transformation times can be determined by modeling the time series of the signal intensities. The host of the dopant could be identified by combining evidence from different analytical techniques including diffraction and electron microscopy. The results about the reaction kinetics are compared to those obtained from caloric measurements. The method opens a way to study the hydration of different hydraulic binders in complex systems selectively, which includes the determination of induction periods and transformation times from in-situ measurements.