Identification of hydration stages: An innovative study of ultrasonic coda waves using integrated sensing element (ISE)

In this study, a piezoelectric-based integrated sensing element (ISE) is prepared and preliminary employed for monitoring the hydration process based on the dominant mechanism of acoustic impedance variation of cement and coda wave idea. The results of the signal for a period of 24 h show that three different stages (0-2 h/2-12 h/ 12-24 h) of the cement during hydration can be distinguished by the reflected coda wave combined with its frequency-domain component, while the first arrival waveform shows almost the same pattern due to the wave trajectory only in packing material. Moreover, the wavelet analysis of the coda wave can distinguish these three stages, in line with the results from the time-domain waveform, energy, and frequency-domain spectrum.