INVESTIGATING FIRE-INDUCED DAMAGE ON FIBER-REINFORCED CONCRETE SAMPLES USING NONDESTRUCTIVE EVALUATION METHODS

Abstract

This research article investigates the effect of severe thermal exposure on the mechanical behavior of fiber-reinforced concrete specimens. Having been exposed to direct fire, the specimens undergo the fracture experiment to determine their mechanical properties. Fire-damage examination is performed with nondestructive techniques such as acoustic emissions (AE) and ultrasonic pulse velocity (UPV). The main purpose is to demonstrate that AE parameters, such as amplitude, cumulative hits, and energy, have a strong correlation with mechanical parameters and temperature. Besides that, acoustic emission monitoring is also an assessment tool of the structural integrity throughout the entire loading process. The distribution of AE events and the variation of key AE parameters across the load process give very useful hints to differentiate between intact and fired-damaged specimens. The fact that the AE can be used on-site to determine cracks means that it may be used as an alternative method to describe concrete's mechanical properties after fire exposures.