Capacitance-based compression self-sensing effectiveness of cement paste with curing time

Capacitance-based self-sensing properties of cement pastes at different curing times were studied in this work. Cement paste samples that did not require any functional materials were tested at 7, 14 and 28 days. Continuous and discontinuous loading cycles (minimum load of 21 kPa and maximum load of 98 kPa) were applied to the cement pastes. It was found that capacitance-based self-sensing is superior to resistance-based self-sensing owing to its greater dependence on stress and reversibility. The capacitance change was found to be irreversible for the 7-day cement paste sample owing to irreversible deformation. Over time, capacitive self-sensing became more effective. The stress sensitivity (fractional increase in capacitance divided by stress) for the 28-day cement paste sample was 2.54 × 10⁻⁸/Pa. It was also found that, with an increase in hydration time, the capacitance decreased, indicating the strength increase in cement paste can also be sensed with capacitance measurements.