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The conductivity σ and the relative dielectric constant k of each sample were measured from room temperature down to −50 ºC. Typical plots of σ and k as a function of temperature for a cement paste of 0.4 w/c ratio (w/c = weight ratio of water to cement used in making the cement paste), hydrated for 15 hours prior to freezing, are displayed in Figs. 4 and 5, respectively.
Figure 4: Logarithm of the D.C. conductivity vs. temperature for an 0.4 w/c ratio cement paste hydrated 15 hours. The quantity Δ log (σ) is defined in the graph by the vertical arrow, indicating the magnitude of the abrupt drop in the conductivity near −8 ºC.
Figure 5: Logarithm of the relative dielectric constant vs. temperature for an 0.4 w/c ratio cement paste hydrated 15 hours.