Geopolymer concrete filled steel tubes at elevated temperatures

Concrete filled tubes have been used in many structural engineering applications, e.g. high rise buildings and bridge piers. During construction the steel tube provides permanent formwork to the concrete. The steel tube can also support a considerable amount of construction loads prior to the pumping of wet concrete, which results in quick and efficient construction. The steel tube provides confinement to the concrete core while the infill of concrete delays local buckling of steel tubes. Compared with unfilled tubes, concrete-filled tubes demonstrate increased ductility and energy absorption during earthquake as well as increased fire resistance. There is a rapid development in concrete technology such as high performance concrete. Geopolymer concretes are emerging new materials promising superior fire resistance and durability and potentially cheaper than the widely used high strength concretes. Production of 1 ton of Portland cement releases 1 ton of green house gases. The geopolymer concrete investigated in this paper utilizes fly ash instead of Potland cement. This paper reports the testing of geopolymer concrete-filled steel tubes at both ambient and elevated temperatures. Results are also compared with those of SCC (self-consolidating concrete) filled tubes.