Strength characteristics of concrete exposed to the elevated temperatures according to the temperature-time curve ISO 834

Brno University of Technology, Faculty of Civil Engineering, Veveří 331/95, 602 00 Brno, Czech Republic

^* Corresponding author: iva.rozsypalova@vutbr.cz

Abstract

While exposed to high temperatures caused by fire, the concrete undergoes a sequence of physical and chemical structure changes causing a mechanical degradation. This paper concerns an experimental strength determination of a temperature stressed concrete. The concrete was temperature loaded according to temperature-time curve ISO 834 and left on a top temperature level for 60 minutes afterwards. This temperature heating rise is in accordance with a common fire expansion in a structure. The concrete panels sized 150 × 1300 × 2300 mm were temperature loaded up to 550, 600, 800 a 1000 °C in a horizontal position in gas furnace for fire testing of structure elements in research Centre AdMaS. The temperatures of the gas in the furnace and the panel was measured during the whole experiment by using the thermocouples. After the fire test, the specimens were drilled out using a 100 mm diameter core drill. The compressive strength and splitting tensile strength tests were made and the results were compared to the reference specimen’s test results. The objective results of a commonly used strength class concrete loaded by elevated temperature corresponding to the real fire exposure differ common linear heat exposure test results and are considered being very valuable.