High-Performance Capacitive Ultrasonic Transducer for Non-Destructive Testing of Concrete Compressive Strength

Ultrasonic non-destructive testing is indispensable for assessing the compressive strength of concrete and is widely utilized in concrete structure health monitoring. However, traditional ultrasonic transducers typically have a large size, narrow bandwidth, and low sensitivity, and often rely on complex circuitry, facing numerous challenges. These limitations hinder their widespread application in real-world engineering practice. To address these challenges, this study proposes the use of Capacitive Micromachined Ultrasonic Transducer (CMUT) technology for non-destructive evaluation of concrete compressive strength. CMUTs offer key advantages, including compact structure, low cost, and high sensitivity, making them well-suited for integration and real-time field applications. Through the use of COMSOL Multiphysics simulations, a strong correlation was observed between the time of flight of ultrasonic waves and concrete compressive strength. Experimental validation was conducted by performing ultrasonic measurements and standard compressive strength tests on concrete specimens. The time of the first highest-amplitude wave (T_FHAW) was extracted as a characteristic parameter and compared against the measured compressive strengths. The results demonstrate a clear linear inverse relationship between T_FHAW and compressive strength, with a coefficient of determination R²= 0.99, confirming the accuracy and reliability of the method. These findings suggest that CMUT-based ultrasonic testing provides an effective and precise approach for non-destructive prediction of concrete compressive strength.