Influence of cavitation erosion on crack propagation behavior of hydraulic concrete under tensile stress

Cavitation erosion is a significant issue in hydraulic concrete structures, particularly in high-flow and high-water-pressure environments. This study is aimed at examining the erosion effects of cavitation bubble collapse on concrete structures, as well as its influence on crack propagation behavior under tensile stress. By employing ultrasonic excitation of bubble clusters, this study examines the variations in macro- and microstructure, mass loss, and tensile splitting strength of concrete over time during cavitation. Furthermore, acoustic emission technology is utilized to analyze the evolution of internal cracks in concrete subjected to tensile stress after cavitation treatment. The findings reveal that cavitation leads to the sequential detachment of cement and aggregate, resulting in the formation of dense interconnected pits and cracks on the surface. During the testing period, the tensile splitting strength of C20, C40, and C60 concrete specimens decreased by 45.99%, 25.92%, and 18.91%, respectively. In the Brazilian splitting test, initial and linear elastic stages of loading show that preexisting cavitation-induced cracks rapidly extend and penetrate at low stress levels, with new cracks forming more frequently and predominantly as small cracks. Approaching the stress peak, the failure is attributed to the long-term accumulation of damage from multiple defects rather than instantaneous crack propagation. Additionally, the proportion of tensile cracks significantly increases, making the specimens more susceptible to failure under tensile stress and resulting in a marked decline in tensile performance. This study highlights the impact of structural changes and the degradation of split tensile strength in concrete due to cavitation on crack evolution behavior under tensile stress. It provides valuable insight for the assessment and maintenance of hydraulic concrete structures.