THE USE OF MRI TO OBSERVE THE STRUCTURE OF CONCRETE

A range of magnetic resonance imaging (MRI) measurements of water in concrete samples and their constituent materials is described and it is demonstrated that MRI can be used to (1) discriminate the spatial distribution of aggregates within a fresh sample, (2) measure changes in water content during the hardening process of cement, and (3) detect fractures and voids within a water-saturated sample. The requirements of the magnetic resonance technique that the sample be free of iron impurities necessitated an investigation of a range of materials for manufacturing suitable concrete samples. This led to a mix design which is representative of normal concretes yet MRI compatible. MRI can achieve image acquisition using a number of different protocols which are defined and optimised according to the equipment available, the properties of the sample and the particular type of image required. Suitable protocols for detecting the water in concrete are described. Magnetic resonance (MR) images of the internal str...

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