Effect of high temperature on mechanical and acoustic emission properties of calcareous-aggregate concrete

In order to investigate the effect of high temperature (25-800 degrees C) on mechanical properties of concrete, uniaxial compression test is carried out to study the relationship between compressive strength and temperature, and the crack development in concrete specimen is monitored based on the acoustic emission (AE) phenomenon to reflect the change of internal cracks of concrete specimen under load. The test results show that the compressive strength of concrete is not obvious when the temperature is below 400 degrees C, but decreases with the increase of temperature and to 20% of that at room temperature when the temperature reaches 800 degrees C. The AE activity in the whole loading process and the cumulative counts and AE energy increase sharply to the critical point C until the specimens are completely damaged. The higher the temperature is, the more seriously the specimens are damaged and the less the acoustic emission signal is generated at the dynamic loading stage. (C) 2016 Elsevier Ltd. All rights reserved.