Microscopic Damage to Limestone under Acidic Conditions: Phenomena and Mechanisms

Abstract

In an acidic environment, the mineral components in rock begin to break down. As a result, the microstructure will be damaged, and then the mechanical properties will deteriorate, which will eventually have a negative effect on engineering stability. In order to study acid damage’s effect on this kind of rock, limestone samples were acidified for 0 days, 5 days, 10 days, 15 days, and 20 days. The microstructure changes in the limestone after acidification were studied via the wave velocity test and electron microscope scanning, and the damage deterioration mechanism was revealed. The results show that the acoustic signal of acidified samples has an obvious absorption effect at high frequency, and the surface pore structure of acidified samples shows fractal characteristics. The P-wave velocity, main peak amplitude, and fractal dimension of the acidified samples did not gradually decrease with time; however, there was a short-term strengthening phenomenon during immersion, which was mainly caused by the formation of CaSO4 crystals.