Iron sand heavy-weight concrete – pre- and post-fire characteristics from wet packing density perspective
M.H. Lai, Yi Min Xie, B.X. Zhang, Fei Ren, S. Kitipornchai, J.C.M. Ho
Abstract
Heavy-weight concrete (HWC) is currently the most widely used radiation shielding material in the nuclear industry. However, the pre- and post-fire mechanical behavior of HWC containing Iron sand (IS) and/or fly ash (FA) is not thoroughly studied. This paper fills in the research gap by testing 12 HWC mixes, which replaced river sand (RS) with 50% or 100% IS and/or ordinary Portland cement (OPC) with 15%, 25% or 35% FA by volume. The temperature-time curve, mass loss, surface change, onset of spalling, failure modes, residual compressive strength, elastic modulus of concrete and stress-strain curve after having exposed to 400, 600, 800 and 1000°C were investigated. Additionally, the pre- and post-fire chemical compositions were analyzed by X-ray diffraction. Results demonstrated that the flowability of HWC increased with the IS / FA replacement ratio due to the more spherical shape and the improved packing structure. Replacing 50% of RS with IS and 15% of OPC with FA could effectively enhance the thermal insulation capacity, compressive strength (increased by 9.5% at 25°C and 400°C, 12.9% at 600°C, 46.0% at 800°C and 63.6% at 1000°C compared with normal concrete) and elastic modulus (increased by 26.3% at 25°C, 17.5% at 400°C, 20.5% at 600°C, 120% at 800°C and 100% at 1000°C compared with normal concrete) of HWC. Lastly, all obtained results suggested that the pre- and post-fire characteristic of HWC containing IS is explicable/predictable by the theory of wet packing density.