Variation of the fracture toughness of concrete with temperature

Abstract

This paper presents an experimental investigation on the variation of residual fracture toughness of concrete with elevated temperatures. A total of 80 beams 150 × 150 × 750 mm were tested under three-point bending, half of which had a 25-mm initial notch at mid-span and the rest of which had a 60-mm initial notch. The temperatures used in the study were 50, 100, 150, 200, 250 and 300 °C. The study also includes cyclic heating effects where the specimens were subjected to cycles of heating and cooling. In each cycle, the specimens were placed in a furnace preheated to the desired temperature for 24 h and then removed and left to cool for another 24 h. The process was repeated for the desired number of cycles. The results show that the residual fracture toughness of concrete decreases with the increase in temperature. The results also show that the fracture toughness is further reduced with the increase of number of heating and cooling cycles.