Ultra-high-performance concrete with Iron ore tailings and non-metallic and hybrid fibers-A comprehensive experimental study

This research discusses the behavior of ultra-high-performance concrete (UHPC) specimens made with dumped waste iron ore tailing (IOT) as a fine aggregate in the mix by 30% and 40% in volume fraction along with mono and hybrid fiber incorporation. Basalt fibers of 1%, 2%, and 3%, polypropylene fibers of 0.18%, 0.20%, and 0.22%, and glass fibers of 1%, 1.5%, and 2% of volume fractions were the non-metallic fibers used. Steel fibers as a metallic factor were kept 1% constant throughout the study. The water-to-binder ratio was maintained between 0.15 and 0.17 after sufficient trials. A high-range water reducer was utilized to improve the flowability of the mix. The experimental investigations confirmed that the SG2 mix with 1% steel and 1.5% glass fiber, and 30% IOT, exhibited improved tensile and impact strength compared to standard conventional concrete. This combination exposed an impact energy of 4.05 x 105 kJ for the first crack and 2.7 x 106 kJ for collapse. The energy taken by the specimen between the first crack and the collapse was about 2.3 x 106 kJ. The microstructure was analyzed using Scanning Electron Microscopy. The non-metallic fibers with dominant mechanical properties were thermogravimetrically analyzed.