Effectiveness of fibres for structural elements in case of fire

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Title: Effectiveness of fibres for structural elements in case of fire

Author(s): György L. Balázs; Éva Lublóy; Olivér A. Czoboly

Publication: Special Publication

Volume: 310

Issue:

Appears on pages(s): 269-278

Keywords: FRC, PFRC, SFRC, fire, spalling.

Date: 3/17/2017

Abstract:

Thin webbed roof girders are sensitive to fire. The first part of our study was directed to the optimization of concrete composition for real-scale roof girders to improve fire resistance.

The application of small polymeric fibres and selecting appropriate filler for the selfcompacting concrete resulted in adequate fire resistance. Experimental results on real-scale elements showed an increase in fire resistance from 12 minutes to 71 minutes. These experiments demonstrated the potential of concrete mix optimization to increase fire resistance as well as decrease sensitivity for spalling.

The purpose of the second part of our experimental study was to analyse the effectiveness of polymeric as well as steel fibres in reducing surface cracking and in improving compressive behaviour subjected to fire. Compressive strength tests were carried out on cubes with 150 mm sides. The concrete compressive experimental strength range was 60 to 75 N/mm². The test variables were concrete composition and maximum temperature (20, 50, 150, 300, 500 and 800 °C). The specimens were tested at room temperature after the heating process and a 2-hour exposure to temperature.

Our test results indicated that the advantageous influence of polymeric fibres in concrete subjected to high temperatures is mainly available for thin fibres and not for thicker fibres. Our test results also indicated that, if steel fibres are used, improvement in fire resistance can be achieved if small diameter fibres with relatively short lengths are used.