The mechanical behavior of a fiber-reinforced concrete after extensive thermal damage is studied in this paper. Undulated steel fibers have been used for reinforcement. After being exposed to direct fire action at the temperature of 850°C, specimens were subjected to bending and compression in order to determine the loss of strength and stiffness in comparison to intact specimens and between the two types. The fire damage was assessed using nondestructive evaluation techniques, specifically ultrasonic pulse velocity (UPV) and acoustic emission (AE). Apart from the strong, well known, correlation of UPV to strength (both bending and compressive), AE parameters based mainly on the frequency and duration of the emitted signals after cracking events showed a similar or, in certain cases, better correlation with the mechanical parameters and temperature. This demonstrates the sensitivity of AE to the fracture incidents which eventually lead to failure of the material and it is encouraging for potential in-situ use of the technique, where it could provide indices with additional characterization capability concerning the mechanical performance of concrete after it subjected to fire.

Date Published: 1 April 2016
PDF: 9 pages
Proc. SPIE 9806, Smart Materials and Nondestructive Evaluation for Energy Systems 2016, 980618 (1 April 2016); doi: 10.1117/12.2220029

Published in SPIE Proceedings Vol. 9806:
Smart Materials and Nondestructive Evaluation for Energy Systems 2016
Norbert G. Meyendorf; Theodoros E. Matikas; Kara J. Peters, Editor(s)