Monitoring the internal swelling in cementitious mortars with single-sided 1H nuclear magnetic resonance

Mortars with different w/c-ratios and binders were dried and rewetted and the subsequent time dependent changes in water filled pore structure were monitored with single-sided 1H nuclear magnetic resonance. This technique combines a localized depiction of all pore water with a good time resolution. The NMR signal is split into the four pore species C-S-H interlayer water, gel pore water, interhydrate water, and capillary water by multi-exponential analysis. Two consecutive running processes in the swelling of cementitious mortars were identified and discussed based on recent models of the cement microstructure as well as its implications on the sorptivity.