The effect of freeze-thaw cycles on the fatigue strength of Travertine

Fatigue failure in materials occurs due to the gradual accumulation of microstructural damage and the propagation of cracks under cyclic loading conditions. This process results in sudden and brittle failure at stress levels significantly lower than the material's static tensile strength. In rock-based infrastructures such as dams, bridges, underground reservoirs, and tunnel walls, fatigue is a crucial factor influencing long-term stability, especially when exposed to environmental stressors like freeze-thaw cycles, seismic activity, and dynamic loads from mining and traffic. In this study, the fatigue behavior of travertine rock was examined under completely reversible cyclic loading to simulate environmental stress conditions. Travertine, a widely used sedimentary rock, has an average compressive strength of 31.4 MPa and is susceptible to environmental degradation. To investigate its fatigue performance, 30 freeze-thaw cycles were applied, alternating between -20°C and +40°C. The process involved saturating the rock samples in water, freezing them, and then allowing them to thaw, completing a full 24-hour cycle. This approach aimed to replicate natural weathering conditions and assess their impact on mechanical properties. A specialized fatigue testing device, inspired by the R.R. Moore system for metal fatigue tests, was used to apply fully reversed sinusoidal loading. This device enables precise control over load amplitude, frequency (variable or constant), and loading rate, making it ideal for evaluating the fatigue performance of rock materials. The stress-life (S-N) curves generated from the experiments revealed a clear inverse relationship between …