Influence of temperature and uniaxial loading on the performance of the embedded intelligent sensing elements (EISE) in cement-based materials

This study investigates the effect of the temperature in a novel embedded intelligent sensing element (EISE) applied in cement-based materials hydration monitoring, and the stability of the signal obtained from EISE after the cement hydration at high temperature and uniaxial compressive test is also characterized. The proposed EISE can evaluate signal stability and surrounding material conditions. Experiments involve signal acquisition using EISE in water at different temperatures, continuous hydration monitoring of ordinary Portland and sulfoaluminate cements, and comparison of signals obtained from EISE before being embedded in sulphoaluminate cement samples and after the EISE has suffered the uniaxial loading and complete removal from the cement. Results show that the temperature variation of water can significantly affect the signal. Stable direct waves during the ordinary Portland cement hydration are characterized. However, sulfoaluminate cement with high exothermic rates (up to 59.6 °C gradient) triggers signal disruptions within 400 minutes, including waveform anomalies and energy fluctuations. The direct waves recover upon cooling, implying reversible thermal impacts. Comparisons of the signals obtained by the EISE before being embedded in cement and after uniaxial compression of the cement sample embedded with the EISE reveal local deformations through the change of coda waves, but the direct waves maintain the same waveforms. Overall, the EISE proves durable for continuous monitoring, effectively identifying temperature- and load-induced disturbances.