Residual mechanical characteristics and spalling resistance of fiber reinforced self-compacting concretes exposed to elevated temperatures

The study presented in this paper concerns the effect that polypropylene fibres have on the properties of SCC of different strength classes when exposed to elevated temperatures. A total of six different SCC and two normal concrete mixtures were produced. The strength classes of the mixtures were C25/30 and C30/37. The specimens produced were placed at the age of 120 days in an electrical furnace and the heat was applied with a rate of 5 degrees C/min. The tested temperatures were 300 degrees C and 600 degrees C. Once reached, the maximum temperature was maintained for 1 h. Then the specimens were naturally cooled down to ambient temperature in the furnace. The properties measured after heat exposures were the compressive strength, splitting tensile strength, water capillary absorption and ultrasonic pulse velocity. It was noticed that, the spalling tendency was increased for specimens of higher strength class C30/37 irrespective of the mixture type (SCC or NVC). Such an explosive behavior was not observed when poly-propylene fibers were added in the mixtures; however, in this case the residual mechanical characteristics of concretes were significantly reduced. (C) 2012 Elsevier Ltd. All rights reserved.