Characterizing blended cement pastes under cyclic freeze-thaw actions by electrical resistivity

This paper presents the characterization of blended cement pastes under freeze-thaw (F-T) loading by electrical resistivity measurement. Silica fume, fly ash, ground granulated blast furnace slag and steel slag were used as the supplemental materials blended with ordinary Portland cement. The electrical resistivity of blended cement pastes was measured under cyclic F-T actions. The depercolation point and ice crystallizing point during freezing, and the repercolation point and ice melting point during thawing can be determined from the logarithm plots of electrical resistivity versus temperature. Both the plots before and after crystallizing points during freezing, and those before and after melting points have linear form. Using the Pearson correlation method, the correlations among evaluated parameters were assessed. The obtained results indicate that both the crystallizing temperature (theta(f)) and the depercolation temperature (theta(DPT)) increase with the F-T cycle number, whereas both the melting temperature (theta(m)) and repercolation temperature (theta(RPT)) decrease with the F-T cycle number. Most pairs of parameters have strong linear correlation with a coefficient of 0.8-1. Hence, the used approach may provide an alternative method to assess the structure alteration of cement-based materials by F-T action. (C) 2013 Elsevier Ltd. All rights reserved.