MEMS Ultrasonic Transducer-Based Nondestructive Testing of Concrete Compressive Strength

A Capacitive Micromachined Ultrasonic Transducer (CMUT)-based ultrasonic method for non-destructive testing of concrete compressive strength is proposed and experimentally validated. A$16 \times 16$CMUT array (postpackaged$200-300 \text{kHz}$) measures time-of-flight (TOF) using the first highest-amplitude arrival (T_FHAW). A 2D finite-element model predicts a monotonic T_FHAW decrease with strength. Tests on$10 \text{cm} \times 10 \text{cm} \times 10 \text{cm}$cubes (C20-C50,$26^{\circ} \mathrm{C}; 0.25 \text{MHz}, 10 \mathrm{V}$, five-cycle bursts) confirm the trend, matching simulation within$\pm 0.1 \mu \mathrm{s}$. Destructive references yield a linear T_FHAW-strength relation ($\mathrm{R}^{2}=0.99$); repeatability is$