Influencing Mechanism of Titanium-Extracted Tailing Slag on the Strength of CaO Steel Slag Hardened Paste

Abstract

Hardened pastes with different mass percentages of steel slag (SS)/titanium-extracted tailing slag (TETS) were prepared under fixed CaO content to determine the influencing mechanism of TETS on the strength of CaO SS hardened paste. Furthermore, the effects and laws of curing time and SS/TETS ratios on the strength of hardened pastes were also investigated in this study. Importantly, hydration products, microstructures and the micro-area compositions of hardened pastes were analysed using X-ray diffraction, Fourier-transform infrared spectroscopy and scanning electron microscopy–energy dispersive spectrometer, respectively, to reveal the influencing mechanism of TETS on the CaO SS hardened pastes. The results demonstrated that the early strength of hardened pastes increases considerably following the inclusion of TETS. Specifically, the strength of the sample with an SS/TETS ratio of 22.5:67.5 at 1 d can be increased by more than 14 times. Notably, its strength at 90 days reached 19.36 MPa. Moreover, the diffraction peaks of calcite and C-S-H in the samples were also strengthened. Meanwhile, a diffraction peak of hydrocalumite appeared, and the calcites in the samples were curled up. When the SS/TETS ratio was equal to or more than 45:45, a diffraction peak of Ca(OH)2 appeared in the sample. Only a diffraction peak of Ca(OH)2 and weak diffraction peaks of calcite and C-S-H were observed in the samples without TETS, but there was no diffraction peak of hydrocalumite. The strength at 90 days was only 4.92 MPa. The increased strength of the hardened paste is closely related to the production of new phases after adding TETS. Solid particles in the hardened paste are cemented into a whole because of the hydration of C-S-H. Calcite forms the skeleton of the hardened pastes, whereas hydrocalumite fills in the pores among particles in hardened pastes, thus making them more compacted. As a result, there is increased.

Optimization of Ratio and Hydration Mechanism of Titanium-Extracted Residual Slag-Based Filling Cementitious Materials

“…Due to the research mentioned above on the resource utilization of TRS, there are still problems of low economic benefits and small processing capacity. Some scholars have begun to pay attention to the development of cementing materials based on titanium tailings extraction and have applied them to mine filling [14]. Therefore, it is of obvious practical significance to explore and develop the titanium-extracted residual slag-based filling cementitious materials based on the activity characteristics of TRS for the resource utilization of TRS.…”

Influences of Friedel’s Salt Produced by CaO-Activated Titanium-Extracted Tailing Slag on Chloride Binding

“…It does not have a self-gelling property. When alkali activation was used in TETS, it showed higher chemical activity [ 4 , 30 ]. Among many alkali activators, CaO has the advantages of safety, environmental protection, easy access to products, and low price, and CaO is the main component of TETS.…”