Spatially resolved relaxometry and pore size distribution by single-point MRI methods: porous media calorimetry

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Abstract
A single-point magnetic resonance imaging study of water freezing in saturated and non-saturated porous materials is presented. Relevant considerations about relaxation time mapping in short relaxation time systems ( of tens to hundreds of microseconds) are discussed and results in concrete and mortar samples under cooling conditions are shown. A spatially resolved estimation of the occupied pore size distribution is achieved in specimens presenting short relaxation times. To the best of our knowledge, this is the first report on the effective determination of spatially resolved pore size distribution of intact concrete materials. Evolution of one-dimensional images as a function of temperature is qualitatively compared with a series of differential scanning calorimetry experiments for cement pastes conditioned under controlled humidity. No supercooling effect is observed in a water saturated concrete single-point imaging experiment.