Evaluation of Fatigue Characteristics of Self-Healing UHPC using Ultrasonic and Natural Frequency Methods

The research focuses on non-destructive testing (NDT) methods to evaluate self-healing effects on the fatigue response of UHPC specimens. The flight time, one of the indices of ultrasonic pulse velocity (UPV) tests has limitations when assessing microscopic cracks. This study explores additional indices, including wave amplitude, energy, and frequency spectrum analysis from the waveform of UPV tests. Together with natural frequency testing (NFT), this allowed a comprehensive assessment of flexural fatigue specimens. As a result, the indices of NDT approached the values of virgin specimens in the healed fatigue specimens, and microscopic observations confirmed crack healing, suggesting these indices are effective for evaluation of self-healing performance.