Transient high concentrations of chain anions in hydrating cement -: indications from proton spin relaxation measurements

Studies of the dynamics of liquid water in the pores of hydrating cement materials were performed by means of various nuclear magnetic resonance techniques, such as spin-echo T-2 relaxometry. echo-detected saturation-recovery T-1 relaxometry and pulsed field gradient diffusometry. While the diffusion coefficients and the transverse relaxation times were found to decrease monotonically with hydration time, the longitudinal relaxation time exhibits a transient minimum during the onset of the acceleration phase. Earlier explanations of the minimum can be ruled out on the basis of our experimental data and a new one is suggested. The findings are corroborated by observations in cement pastes with added fine particles.