Based on a 10-year climate survey for Oklahoma City, OK, three exposure regimens were devised: cyclic high temperature exposure, cyclic freezing-and-thawing exposure, and cyclic wetting-and-drying exposure. A total of four different test methods were compared to determine the extent of damage induced by the exposure mechanisms. Two standard nondestructive methods—ultrasonic pulse velocity and resonant frequency—were compared along with compression load testing.
It was found that resonant frequency testing was more sensitive to microcrack formation. All methods discerned a change in properties after 30 cycles of freezing-and-thawing exposure. Interestingly, all three exposure regimens demonstrated a similar extent in degradation after 90 exposure cycles; however, high temperature and wet-dry cyclic exposure induced further damage than freezing-and-thawing-induced damage.
Moreover, acoustic emission (AE) monitoring was performed during mechanical loading. A simple AE parameter-based evaluation confirmed the presence of material distress as that found for the destructive and nondestructive evaluation.