Monitoring the early hydration of pozzolan—Ca(OH)₂ mixtures using electrical methods

This paper utilizes electrical methods to follow the early hydration characteristics of pozzolanic materials activated with powdered calcium hydroxide at room temperature (20°C). The electrical response is measured in terms of conductance and capacitance. Four materials are studied: ground granulated blastIurnace slag, microsilica, metakaolin and pulverized fuel ash (the last from three different sources). The work shows that monitoring the temporal change in electrical parameters can exploited as a potentially usefit! test method for identifying the stages of hydration and studying the rate of reaction over these stages. To this end, different formats of data presentation are exploited. It was shown that the capacitance of the material displays a marked frequency dependence over the range of the current study (10a Hz to 10kHz); the influence of frequency of applied field on conductance was less pronounced.