Artificial pozzolana were made by firing of two types of clays at two temperatures (600 and 700 degrees C). Different artificial pozzolana-Portland cement pastes were made using a water/cement ratio of 0.40 by weight of the cement blend. Each cement paste was examined for hydration kinetics at 20 degrees C as well as electrical conductance at 20 and 35 degrees C. The results of hydration kinetics indicated a sort of phase transformation of hydration products at the intermediate stages of hydration. Electrical conductance studies demonstrated two maxima at 20 degrees C; only one maximum at 35 degrees C was detected at the early stages of hydration. All results could be related to the sequence of the initial hydration reaction and the mode of disruption of the electrically insulating coating layers around the grains of the cement constituents. [References: 17]
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