Study of mechanisms of explosive spalling in high-strength concrete at high temperatures using acoustic emission

Mechanisms behind explosive spalling of high-strength concrete during a heating test were investigated on the basis of acoustic emission (AE) measurements of wet and air-dried specimens. The relation between the measured values of the internal temperature and vapour pressure and AE events produced by micro-cracking were investigated. It was found that AE events were indeed indicative of the state of the explosive failure process. Furthermore, b-value analysis was successfully applied to clarify the fracture process, regardless of the moisture content of the specimens.