Electric polarization in carbon fiber-reinforced cement

Electric polarization induced an increase of the measured electrical resistivity of carbon fiber-reinforced cement paste during resistivity measurement. The effect was diminished by increasing the conductivity of the cement paste through the use of carbon fibers that were more crystalline, the increase of the fiber content, or the use of silica fume instead of latex as an admixture. Intercalation of crystalline fibers further increased the conductivity of the composite, but it increased the extent of polarization. Voltage polarity switching effects were dominated by the polarization of the sample itself when the four-probe method was used, but were dominated by the polarization at the contact-sample interface when the two-probe method was used. Polarization reversal was faster and more complete for the latter.