Pyroelectric behavior of cement-based materials

The pyroelectric effect, which is useful for temperature sensing, was observed in cement-based materials. The use of short steel fibers (8 μm diameter), together with polyvinyl alcohol (PVA), as admixtures greatly enhances the effect, thereby attaining pyroelectric coefficient 6×10⁻⁸ C/m² K (10 kHz). However, due to the high value (2500) of the relative dielectric constant, the pyroelectric voltage is lower than those of plain cement paste or carbon fiber (15 μm diameter) cement paste. Carbon fiber cement paste and plain cement paste are comparable in the pyroelectric voltage, though the pyroelectric coefficient is higher for carbon fiber cement paste than plain cement paste. The pyroelectric effect in cement-based materials is attributed to the increase in mobility of the ions as the temperature increases.