Basic oxygen furnace slag as a support material for the cultivation of indigenous marine microalgae

The use of industrial waste as a potential stabilizer of marginal construction materials is cost effective. Phosphogypsum and fly ash are industrial wastes generated in very large quantities and readily available in South Africa. In order to explore the potential stabilization of vastly abundant expansive soil using larger quantity phosphogypsum waste as a potential modifier, composites with a mixture of lime-fly ash-phosphogypsum-basic oxygen furnace slag were developed. However because of the presence of radionuclide, it was necessary to treat the phosphogypsum waste with mild citric acid. The effect of the acid treatment on the geotechnical properties and microstructure of expansive soil stabilized with phosphogypsum-lime-fly ash-basic oxygen furnace slag (PG-LFA-BOF) paste was evaluated, in comparison with the untreated phosphogypsum. Expansive soil stabilized with acid-treated PG-LFA-BOF paste exhibited better geotechnical properties; in particular, the high strength mobilized was associated primarily with the formation of various calcium magnesium silicide and coating by calcium silicate hydrate and calcium aluminate hydrate. The soil microstructure was improved due to the formation of hydration products. The stabilized expansive soil met the specification for road subgrades and subbase. Stabilization of expansive soils with phosphogypsum, fly ash, and basic oxygen fly ash does not only improve engineering properties of soil but also provides a solution in relation to disposal and environmental pollution challenges.

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Basic oxygen furnace slag: Review of current and potential uses

Minerals Engineering ◽

10.1016/j.mineng.2020.106234 ◽

2020 ◽

Vol 149 ◽

pp. 106234 ◽

Cited By ~ 3

Author(s):

Tamlyn Sasha Naidu ◽

Craig Michael Sheridan ◽

Lizelle Doreen van Dyk

Keyword(s):

Basic Oxygen Furnace ◽

Basic Oxygen ◽

Basic Oxygen Furnace Slag ◽

Furnace Slag

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Feasibility and Characterization Mortar Blended with High-Amount Basic Oxygen Furnace Slag

Materials ◽

10.3390/ma12010006 ◽

2018 ◽

Vol 12 (1) ◽

pp. 6 ◽

Cited By ~ 1

Author(s):

Wei-Ting Lin ◽

Chia-Jung Tsai ◽

Jie Chen ◽

Weidong Liu

Keyword(s):

Steel Industry ◽

Setting Time ◽

Basic Oxygen Furnace ◽

Cementitious Material ◽

Partial Replacement ◽

Supplementary Cementitious Material ◽

Basic Oxygen ◽

Basic Oxygen Furnace Slag ◽

Furnace Slag ◽

Weight Proportion

Basic oxygen furnace slag (BOFS) was ground to three levels of fineness as a replacement for cement at weight proportions of 10, 30, 50, and 70 wt.%. Fineness and weight proportion were shown to have significant effects on the flowability and setting time of the mortars. The expansion of BOFS mortars increased with an increase in the proportion of cement replaced, thereby exacerbating the effects of cracking. Optimal mechanical properties were achieved when 10 wt.% of the cement was replaced using BOFS with fineness of 10,000 cm2/g. The compressive strength of BOFS mortar is similar to that of ordinary Portland mortar, which makes BOFS suitable for the partial replacement of cement as a supplementary cementitious material. Scanning electron microscopy results revealed that the reaction of CaO with H2O results in the formation of C–S–H colloids, whereas the reaction of SiO2 with Al2O3 produces C–A–S–H colloids. The use of BOFS as a partial replacement for Portland cement could make a tremendous contribution to the steel industry and help to lower CO2 emissions.

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