Concrete is a widely used material in civil construction and may be submitted to high working temperatures under various circumstances. Many factors influence the behavior of this material at high temperatures, which ...Concrete is a widely used material in civil construction and may be submitted to high working temperatures under various circumstances. Many factors influence the behavior of this material at high temperatures, which usually leads to the evaporation of the hydrated cement. The dehydrated cement undergoes a contraction, simultaneously with the thermal expansion of the inert fraction of the material. As a consequence of these conflicting expansions and contractions, the material cracks and its strength and modulus of elasticity decrease significantly. On the other hand, the addition of short metallic fibers to the material increases its toughness, probably due to its action on the cracking behavior of the composite. It is thus expected that a concrete containing metallic fibers should maintain its original properties even after exposure to elevated temperatures. This paper presents an evaluation of the influence of steel fibers on the microstructure and toughness of concretes submitted to high tenaperatures. The bending behavior, under strain rate control, of concretes with a strength of 30 MPa and containing short steel fibers, submitted to a previous treatment at 500 ℃, was analyzed. It was observed that, after both heat treatments, the addition of metallic fibers to concrete was able to maintain the pseudo-ductility and load-carrying capacity of this composite material.展开更多
文摘Concrete is a widely used material in civil construction and may be submitted to high working temperatures under various circumstances. Many factors influence the behavior of this material at high temperatures, which usually leads to the evaporation of the hydrated cement. The dehydrated cement undergoes a contraction, simultaneously with the thermal expansion of the inert fraction of the material. As a consequence of these conflicting expansions and contractions, the material cracks and its strength and modulus of elasticity decrease significantly. On the other hand, the addition of short metallic fibers to the material increases its toughness, probably due to its action on the cracking behavior of the composite. It is thus expected that a concrete containing metallic fibers should maintain its original properties even after exposure to elevated temperatures. This paper presents an evaluation of the influence of steel fibers on the microstructure and toughness of concretes submitted to high tenaperatures. The bending behavior, under strain rate control, of concretes with a strength of 30 MPa and containing short steel fibers, submitted to a previous treatment at 500 ℃, was analyzed. It was observed that, after both heat treatments, the addition of metallic fibers to concrete was able to maintain the pseudo-ductility and load-carrying capacity of this composite material.
