The morphology of C–S–H: Lessons from 1H nuclear magnetic resonance relaxometry

1H nuclear magnetic resonance has been applied to cement pastes, and in particular calcium silicate hydrate (C–S–H), for the characterisation of porosity and pore water interactions for over three decades. However, there is now renewed interest in the method, given that it has been shown to be non-invasive, non-destructive and fully quantitative. It is possible to make measurements of pore size distribution, specific surface area, C–S–H density and water fraction and water dynamics over 6 orders of magnitude from nano- to milli-seconds. This information comes in easily applied experiments that are increasingly well understood, on widely available equipment. This contribution describes the basic experiments for a cement audience new to the field and reviews three decades of work. It concludes with a summary of the current state of understanding of cement pore morphology from the perspective of 1H NMR.