Estudo da influência das adições minerais no comportamento do concreto sob a ação do fogo

Abstract

The present study assessed the behavior of concrete produced from mineral additions when subjected high temperatures typical occurrence in fire. Representative speciments were shaped using only Portland cement CP V- ARI as binder, and others, with the same amount of binder, but replacement cement by mineral additions like blast furnace slag low reativity, blast furnace slag high reativity (basic) silica fume and metakaolim. After 90 days, the specimens were submitted to a fire located through a blowtorch, being carried out measurements of temperatures recorded in different points of the sample. Subsequently were evaluated compressive strength, tensile strength by diametral compression, dynamics elasticity of the modal, and absorption of water by total immersion. It was evaluated the flow of heat transmitted through the speciment. The specimens behavior with mineral additions were compared with specimens without mineral additions. Results showed that there is a sensitivity to fire in concretes with silica fume and invariably a reduction of mechanical strength and dynamic elasticity module. Not only that, but an increase in the absorption of water by total imersion, for all speciments.. Regarding the flow of heat through the concrete containing as binders Portland cement and silica fume as well as through the concrete composed of Portland cement, silica fume and blastfurnace slag high reactivity (basic), it was found that they had to behave differently from the rest of the concretes studied, because those concretes spread the heat on a slower.