Fiber Reinforced Concrete After Elevated Temperatures: Techniques of Characterization

Abstract

The mechanical properties of fiber reinforced concrete (FRC) are negatively affected when subjected to elevated temperatures. The main concern is regarding its post-crack tensile strength, which can be severely impaired at temperatures above 300 °C. In this composite, the mechanical characterization is constantly performed by means of bending tests of prismatic specimens, as recommended by EN 14651. However, due to limiting aspects, alternative methodologies have been used for the characterization of FRC, among which are the DEWS (Double Edge Wedge Splitting) and the Double Punch tests. In this context, the present study compares the methodologies for evaluating the mechanical behavior of FRC after elevated temperatures, discussing and emphasizing its advantages and limitations. The Double Punch test does not show satisfactory response as a consequence of the degradation suffered by the sample and the puncture interaction induced by the test. On the other hand, the indirect tensile DEWS test shows that it is capable of characterizing the FRC even after exposure to elevated temperatures. Although the post-crack response of the composite varies according to the method adopted, the post-crack tensile strength in the service limit state (SLS) and ultimate limit state (ULS) are considerably reduced when compared with the ambient temperature.