Acoustic emission (AE) characteristics of limestone during heating

Limestone is a widely used natural building material, and its physical and mechanical properties can change greatly when exposed to high-temperature heat sources. In this paper, limestone samples from Linyi City, Shandong Province, were selected and some of them were heated to 650 °C at different heating rates (4, 6, and 8 °C min −1 ), while the rest of the samples were heated cyclically (200, 300, 400, 500, 600, and 650 °C) at a heating rate of 8 °C min −1 , and the acoustic emission (AE) signals were recorded throughout. The results show that the AE signal rate increases with increases in temperature, and the AE signal increases rapidly at 300 °C and 500 °C because of the thermal decomposition of dolomite and calcite. There is a negative correlation between the heating rate and the AE signal rate. The high-frequency data and high-amplitude data generated by AE are negatively correlated with the heating rate. With the increase in the heating rate, AE counts and cumulative AE counts decrease significantly.