NMR Line Shape‐Spin‐Lattice Relaxation Correlation Study of Portland Cement Hydration

The proton free induction decay of a portland cement paste in an advanced stage of hydration can be roughly divided into three main components: (1) a component with a very short spin‐spin relaxation time, T 2 , representing the protons of the solid OH groups and the water of crystallization, (2) a component with an intermediate T, representing the bonded water in the gel phase, and (3) a third component with a relatively long T 2 representing the water in the micropores and layers. The dependences of the intensities, T 2 's, and spin‐lattice relaxation times (T 1 's) of these three components on the cement hardening time have been determined. The proton spin‐lattice relaxation time of the “solid” component increases with hardening time whereas T 1 decreases for the other two components. The observed time dependence of the diffusion coefficient, D, of water in a tricalcium silicate paste supports the findings of the above correlation study.