Real Fire Test on Concrete Columns and Post-tensioned Slabs

An enclosure fire test was conducted incorporating high strength reinforced concrete columns and normal strength post-tensioned floor slabs. The slabs formed part of the roof whilst the columns within the enclosure were unloaded except for compressive stresses induced by the prestressing bar located at the centre of each of the columns. The columns and slabs were made from commonly available but markedly different Australian aggregates. Some of the columns incorporated 6mm monofilament polypropylene (pp) fibres introduced into the concrete mix at a concentration of 1kg per m 3 of concrete. With the exception of columns with pp fibres, spalling commenced within 10 minutes of the start of the test with all columns experiencing extreme spalling. The test was terminated at 68 minutes due to failure of one of the posttensioned slabs. Minimal spalling was obtained for slabs constructed from basaltic aggregate. The implications of the findings are considered with respect to the design of reinforced concrete structures.