Abstract
Iron tailing powder (ITP) is considered to have the potential to replace cement to manufacture ultra-high-performance concrete (UHPC). However, the performance of UHPC with the addition of ITP after exposure to high temperatures is more complex. This investigation prepares seven UHPC formulations by introducing different contents of ITP and investigates the mechanical behavior (residual strength), bound water content, and microstructural properties (crystalline and amorphous phases, chemical structure, and morphology) of UHPC subjected to elevated temperatures. The experimental results show that the addition of ITP postpones the spalling of concrete when exposed to high temperatures. The concrete incorporating 15% ITP maintains 53.8% of its original strength at 800°C, unlike the concrete without ITP that maintains 31.6% of its original strength. The addition of ITP increases the number of micropores/cracks in concrete and helps release the vapor pressure caused by water evaporation. The findings of this investigation highlight the potential application of ITP for future UHPC design and manufacture.
Highlights
Concrete can endure high temperatures owing to its high specific heat and low thermal conductivity [1], which, does not imply that its performance is not degraded at all
Mechanical behavior and microstructural properties of ultra-high-performance concrete (UHPC) containing Iron tailing powder (ITP) at high temperatures were investigated in this study
Residual strength and bound water content of UHPC mortars were discussed. Their microscopic investigation was studied by XRD, TGA, FTIR, and SEM techniques. e main findings can be concluded as follows: (1) e addition of ITP particles has accelerated the hydration of cement and the filling effect of ITP refined the pore structure, which contributed to the strength development of UHPC mortars
Summary
Concrete can endure high temperatures owing to its high specific heat and low thermal conductivity [1], which, does not imply that its performance is not degraded at all. The internal physical/chemical changes of concrete at high temperatures affect its mechanical strength [3, 4]. It has been reported that the residual strength of concrete could significantly reduce when subjected to elevated temperatures [5]. Ultra-high-performance concrete (UHPC) has extremely low permeability and porosity [6, 7], which means that the build-up of thermal pressure that existed in the pores is extremely high. The high thermal pressure could cause the concrete to explosive spalling [8].
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