A methodology to estimate the ultrasonic p-wave velocity of coarse aggregates in concrete

Ultrasonic wave propagation is widely used for material characterization, although accurately determining the wave velocity of coarse aggregates remains challenging due to their irregular geometry and heterogeneous distribution in concrete. This study proposes a methodology to estimate coarse aggregate p-wave velocities from time-of-flight (TOF) measurements in concrete prisms, enabling a more reliable determination of their dynamic elastic modulus. The methodology was validated through numerical simulations and experimental tests incorporating different aggregate types and maximum particle sizes. A strategy was developed to simultaneously estimate both matrix and coarse aggregate velocities, and its performance was assessed using the mean absolute error (MAE) and a combined normalized MAE. Results showed that the methodology achieves relative errors below 1 % in several cases, regardless of aggregate type. Overall, the proposed approach provides a practical and robust tool for improving the mechanical characterization of coarse aggregates, including unconventional or recycled materials.