The evolution of cement paste hydration process by impedance spectroscopy

Impedance spectroscopy (I.S.) measurements were carried out on ordinary portland cement paste, cured in 100% relative humidity environment, at different temperatures. The results collected during 28 d show that the electrical conductivity decreases to an almost constant value. The higher the curing temperature the shorter is the time necessary to obtain the quasi-steady-state conditions. A thermally activated conduction mechanism in cement paste was observed. The possibility of using I.S. (a non-destructive and in-situ technique) to follow the evolution of the cement paste hydration process was validated by traditional techniques (X-ray diffraction and thermogravimetry). Very good agreement was obtained. (C) 2001 Elsevier Science B.V. All rights reserved.