A Method for Identifying Hydration Stages of Concrete Based on Embedded Piezo-Ultrasonic Active Sensing Technology

Area of Science:

• Materials Science
• Civil Engineering
• Structural Health Monitoring

Background:

• Concrete's structural evolution during hydration impacts its strength.
• Continuous monitoring of concrete curing is crucial for materials science research.
• Identifying key hydration stages aids in predicting concrete performance.

Purpose of the Study:

• To propose and evaluate an embedded ultrasonic active sensing technique for monitoring concrete hydration.
• To identify critical structural transition stages during concrete curing using piezoelectric ceramics (PZT).
• To develop a novel index for classifying and identifying hydration stages in concrete.

Main Methods:

• Fabrication and performance evaluation of a piezoelectric ultrasonic sensor.
• Conducting compressive strength and penetration resistance tests.
• Analyzing piezoelectric signal amplitude and wavelet packet energy (WPE) evolution during hydration.
• Introducing a WPE-based root mean square deviation (WPE-RMSD) index for transition identification.

Main Results:

• The developed PZT sensor demonstrated stable electrical, mechanical, and waterproof properties.
• Both signal amplitude and WPE effectively captured concrete hydration, with WPE showing higher sensitivity.
• The WPE-RMSD index provided continuous monitoring from early hydration to 28-day densification.
• The WPE-RMSD index successfully identified critical stages like final setting and the 7-day period.

Conclusions:

• The embedded ultrasonic sensing technique offers a novel in situ approach for concrete hydration monitoring.
• The WPE-RMSD index is effective in classifying and identifying key structural transition stages.
• This method enhances the understanding and control of concrete curing processes.