Comportamento do concreto de ultra alto desempenho reforçado com fibras sob elevadas temperaturas: revisão sistemática da literatura

Abstract

The ultra-high performance fiber reinforced concrete (UHPFRC) is a promising material for modern construction as it exhibits superior mechanical strength and durability compared to conventional concrete. However, despite the development of numerous studies, there is still no complete understanding of its properties and behavior when exposed to elevated temperatures, which are highly dependent on the fibers incorporated into the material. Therefore, the present study aims to provide a literature review of the most recent research on this topic, focusing on the mechanical properties, microstructural changes, and resistance to explosive spalling of the composite under high-temperature exposure, according to the types of fibers present in its matrix. Furthermore, a discussion was conducted regarding the incorporation of natural and recycled fibers into concrete in order to reduce its environmental impact. To achieve these objectives, articles published in the last five years were retrieved from the Web of Science database and subjected to several filtering stages to exclude studies that did not align with the scope of this work. As a result, 27 studies were selected and included in the review. The analysis revealed that the mechanical performance of UHPFRC is highly influenced by steel fibers, which are currently the most widely used reinforcement. However, steel fibers alone are not capable of preventing explosive spalling. Consequently, the most common solution is the use of hybrid fiber systems, especially combinations of steel and synthetic fibers, which increase porosity and reduce internal stresses through the synergistic effects of different fiber types and concentrations. Finally, it was concluded that among synthetic fibers, polypropylene fibers are the most effective, because of their lower melting point and higher coefficient of thermal expansion. These characteristics enable them to efficiently prevent spalling while also contributing to improvements in mechanical properties. In addition, natural and recycled fibers were identified as promising alternatives for mitigating spalling without compromising its mechanical performance, although further research is still required.