Combined fiber technique for spalling protection of concrete column, slab and beam in fire

In this study, a combined fiber technique is applied to large high strength concrete specimens with different boundary conditions, and its effects on the fundamental properties of concrete and the spalling protection of concrete are investigated. Experimental test results showed that the application of the combined fiber technique could achieve the least reduction of slump flow, which, in turn, solved the problem of conventional fiber technique for the same level of spalling protection of concrete. Fiber content used for the combined fiber technique was 50 % less than the normal content used for the conventional fiber technique. In addition, this study proved that the new combined fiber technique is applicable to large specimens, but the level of its effectiveness is different. It was demonstrated that this different effectiveness of the combined fiber technique applied to columns, slab and beam is due to their size and boundary conditions.