X-ray microtomography was successfully applied to observing water movement from saturated LWA to the surrounding cement paste during hydration. Following the application of a 5 voxel x 5 voxel x 5 voxel median filter to each acquired three-dimensional image set, the volume of internal curing water supplied to the paste as a function of time was readily estimated, based on analysis of each specimen’s greylevel histogram. This estimated volume of curing water closely followed the same trends as the degree of hydration measured by three different techniques (LOI, chemical shrinkage, and isothermal calorimetry). For this particular mortar, much of the water movement occurred during the first 24 h of hydration, emphasizing the importance of proper early-age curing. In the future, it would be of interest to repeat the freezing portion of this study by cooling the specimen to about -20oC, at which temperature freezing within the porous cement paste microstructure should definitely occur.
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