Strong piezoresistivity and piezopermittivity of cement-based material without functional admixture and their correlation.

The strong piezoresistivity and piezopermittivity inherent in cement paste without functional admixture are evaluated and unprecedentedly correlated, with relevance to resistance-based and capacitance-based structural self-sensing, respectively. Compression (low elastic regime) decreases the resistivity and increases the permittivity, indicating respectively positive piezoresistivity (unprecedentedly high gage factor ≤20400) and negative piezopermittivity (magnitude of the fractional change in capacitance per unit strain ≤4710). Both effects are strengthened by decreasing the strain (8 × 10−8–7 × 10−7), or increasing either the frequency (2–100 kHz) or electric field (0.09–0.50 V/mm). The resistivity decreases greatly with increasing frequency, while the permittivity decreases less, both because of the sluggishness of the ion movement. Electric field increase raises the capacitance/resistance. Upon unloading, the capacitance decreases to below that before loading. The electrodes sandwich the specimen, being adjacent to the stressed region. The fringing electric field reaching the stressed region facilitates the sensing, being strengthened by increasing the frequency or electric field. • Strong piezoresistivity and piezopermittivity inherent in cement paste are reported. • They relate to resistance-based and capacitance-based structural self-sensing. • Cement paste with no functional admixture is investigated in the elastic regime. • Compression decreases the resistivity and increases the permittivity. • The piezoresistivity and piezopermittivity are strengthened by reducing the strain. [ABSTRACT FROM AUTHOR]