Improvement of residual compressive strength and spalling resistance of high-strength RC columns subjected to fire

This paper investigates the spalling properties of high-strength concrete in order to improve the residual compressive strength and spalling resistance in specimens subjected to 3 h of unloading. re conditions. This study consists of three series of experiments with eighteen different specimens varying in fiber type and content, finishing material and simultaneous fiber content and lateral confinement. They were fabricated to a 300 x 300 x 600 mm mock-up size. Results of the. re test showed that the control concrete was explosive, while the specimens that contained more than 0.1 vol% of polypropylene (PP) and polyvinylalcohol (PVA) fibers were prevented from spalling. One specimen, finished by a. re endurance spray, exhibited even more severe spalling than the control concrete. The specimen containing 0.1 vol% of PP fiber and using a con. ning metal fabric at the same time, showed the most effective spalling resistance; in particular, the residual compressive strength ratio was even higher than that of the control concrete before the. re test. It was demonstrated that adding fibers in concrete prevented the spalling occurrence and con. ning metal fabric around the main bars of concrete specimens can secure the strength of structures during the conditions of elevated temperature. (C) 2008 Elsevier Ltd. All rights reserved.