Influence of high temperature on the mechanical properties of hybrid fibre reinforced normal and high strength concrete

The current version of the European standard for concrete structures gives tabulated data for the evolution of the mechanical properties of normal strength concrete subjected to elevated temperatures. However, the standard acknowledges the lack of sufficient data for the case of high strength concrete with limestone aggregate and there are no provisions for fibre reinforced concrete at high temperatures. This paper presents the experimental results obtained on six batches of normal and high strength fibre reinforced concrete made with limestone aggregates and tested after exposure to high temperatures. These results gave a good correlation with previous researches and equations were obtained to describe the evolution of the compressive strength and the flexural strength at elevated temperatures. Ductility was also measured in the flexural strength tests and results suggested that the use of steel fibres with higher aspect ratio may lead to lower ductility after exposure to temperatures higher than 650 °C.