CONCRETE MORTAR WATER PHASE-TRANSITION STUDIED BY SINGLE-POINT MRI METHODS/

A series of magnetic resonance imaging (MRI) water density and T-2 pr ofiles in hardened concrete and mortar samples has been obtained durin g freezing conditions (-50 degrees C < T < 11 degrees C). The single-p oint ramped imaging with T, enhancement (SPRITE) sequence is optimal f or this study given the characteristic short relaxation times of water in this porous media (T-2 < 200 mu s and T-1 < 3.6 ms). The frozen a nd evaporable water distribution was quantified through a position bas ed study of the profile magnitude. Submillimetric resolution of proton -density and T-2-relaxation parameters as a function of temperature h as been achieved. (C) 1998 Elsevier Science Inc.