ABSTRACT
The addition of fibers to the cementitious matrix, giving rise to fiber-reinforced concrete, aims to improve the low ductility observed in concrete mechanical response under different load scenarios, particularly under direct tension. In this work, cracking and mechanical degradation processes of concrete elements using acoustic emission technique are examined, with the objective of analyzing the incidence of high temperatures on the failure behavior of high-strength concrete beams with and without fibers. Results of an experimental campaign including different mechanical tests on concrete specimens with and without the addition of a hybrid combination of steel and polypropylene fibers are presented. The incorporation of polypropylene fibers is intended to improve the behavior of concrete against elevated temperatures. The evolution of acoustic emission measurements during bending tests and its relation with the mechanical response is analyzed. It is observed that after being exposed to a temperature of 600°C, properties of fiber reinforced concrete were relatively less affected than those of plain concrete, retaining some capacity to absorb energy in the post-peak regime. It is also confirmed that the monitoring technique used, has a direct correlation with the degradation process of concrete.
Keywords
High-strength concrete; Fiber-reinforced concrete; Acoustic emission; High temperature; Three-point-bending test
