Effect of Freeze-thaw Cycles on Microstructure and Mechanical Properties of Limestone

Abstract

In studying the effect of freeze-thaw cycles on the microstructure and mechanical properties of limestone, scanning electron microscope, low-field nuclear magnetic resonance, and uniaxial compression tests are carried out on the limestone samples dried and subject to 5, 10, 15, and 20 freeze-thaw cycles. Through analysis and discussion, it was found that the number of freeze-thaw cycles has a significant effect on the microstructure of the limestone samples. Compared to the dry samples, the number of microcracks of the limestone samples subjected to freeze-thaw cycles is increased. Moreover, the crack width is positively correlated to the number of freeze-thaw cycles. With an increase in freeze-thaw cycles, the signal intensity of the T2 spectrum is considerably increased, and the connectivity of the micropores and fissures is increased. In addition, the peak compressive strength and elastic modulus showed a significant negative correlation with the number of freeze-thaw cycles. Again, compared to the dry samples, the peak compressive strength of the samples subject to 5, 10, 15, and 20 freeze-thaw cycles decreased by 14.7%, 22.0%, 28.7%, and 37.5%, respectively. The elastic modulus also decreased by 8.0%, 11.4%, 11.7%, and 21.5%, respectively. Therefore, these findings provide basic parameters for the stability evaluation of rock slopes in Northwest Guizhou.