scholarly journals Recycling of Basic Oxygen Furnace Slag as a Raw Material for Autoclaved Aerated Concrete Production

2020 ◽  
Vol 12 (15) ◽  
pp. 5896
Author(s):  
Ying-Liang Chen ◽  
Chun-Ta Lin
Keyword(s):  
Basic Oxygen Furnace ◽  
Essential Elements ◽  
Raw Material ◽  
Basic Oxygen ◽  
Autoclaved Aerated Concrete ◽  
Concrete Production ◽  
Bof Slag ◽  
Aerated Concrete ◽  
Basic Oxygen Furnace Slag ◽  
Furnace Slag

The purpose of this study was to recycle basic oxygen furnace (BOF) slag in the production of autoclaved aerated concrete (AAC), and to examine the influence on the properties of AAC products. The magnetic substances in the BOF slag accounted for about 15 wt.% and the magnetic proportion increased as the particle size decreased. The nonmagnetic portion of the BOF slag was acquired by a magnetic separation process and its major constituents were Ca (~42 wt.% as CaO) and Si (~35 wt.% as SiO2), which are the essential elements of AAC. When using the BOF slag for AAC production, the bulk density and compressive strength of the specimens decreased as the amount of slag increased. The results of the performance analysis revealed that at appropriate water–solids ratios, using 15 wt.% or less of the BOF slag was beneficial to the properties of the AAC products. In general, it should be feasible to recycle the BOF slag in the production of AAC. However, the foreign elements introduced by the BOF slag can alter the formation and structure of hydrates, including tobermorite, and thus affect the properties of the AAC product, a potential issue that needs to be addressed.

scholarly journals Utilization of Basic Oxygen Furnace Slag in Geopolymeric Coating for Passive Radiative Cooling Application

2020 ◽  
Vol 12 (10) ◽  
pp. 3967 ◽  
Author(s):  
Chia-Ho Wu ◽  
Chih-Hong Huang ◽  
Yeou-Fong Li ◽  
Wei-Hao Lee ◽  
Ta-Wui Cheng
Keyword(s):  
Layer Structure ◽  
Research Work ◽  
Temperature Drop ◽  
Basic Oxygen Furnace ◽  
Radiative Cooling ◽  
Portland Cement Concrete ◽  
Basic Oxygen ◽  
Bof Slag ◽  
Basic Oxygen Furnace Slag ◽  
Furnace Slag

Basic oxygen furnace slag (BOFs) is difficult to reutilize because it contains excessive free lime, and thus causes serious expansion. For this reason, how to reuse BOF slag has turned out to be an imperative issue in order to meet the concept of a circular economy. The key intention of this research work is to develop a new way to reutilize BOF slag, which due to its high emissivity in the 8–13 µm wavelength range, can be used as a sustainable, passive radiative cooling material. Passive radiative cooling, without the consumption of any energy, achieves the cooling of a surface by reflecting the sunlight and radiating the heat throughout the outer space (not absorbed by the atmosphere). BOF slag is used as a radiative cooling material in geopolymeric coating. This coating possesses an emissivity of 0.95 within the range of 8–13 µm and also has high conductivity, but its gray appearance absorbs too much heat. Therefore, by improving the situation through a double-layer structure, a temperature drop of 5.9 °C was reached compared to non-coated concrete under simulated sunlight, simultaneously with a low heating rate and high cooling rate. Besides, the binding strength between the geopolymeric coating and Portland cement concrete is comparable to two commercial organic paints. It is highly probable that the utilization of BOF slag in geopolymeric coating is energy saving and also feasible for passive radiative cooling applications. Hence, it can greatly decrease indoor temperature and improve the comfort of people living in buildings.

scholarly journals Component Modification of Basic Oxygen Furnace Slag with C4AF as Target Mineral and Application

2021 ◽  
Vol 13 (12) ◽  
pp. 6536
Author(s):  
Yanrong Zhao ◽  
Pengliang Sun ◽  
Ping Chen ◽  
Xiaomin Guan ◽  
Yuanhao Wang ◽  
...  
Keyword(s):  
Intermediate Phase ◽  
Raw Materials ◽  
Activity Index ◽  
Basic Oxygen Furnace ◽  
Hydration Products ◽  
Basic Oxygen ◽  
Bof Slag ◽  
Mineral Compositions ◽  
Slag Component ◽  
Basic Oxygen Furnace Slag

In this paper, a new method of basic oxygen furnace (BOF) slag component modification with a regulator was studied. The main mineral was designed as C4AF, C2S and C3S in modified BOF slag, and the batching method, mineral compositions, hydration rate, activation index and capability of resisting sulfate corrode also were studied. XRD, BEI and EDS were used to characterize the mineral formation, and SEM was used to study the morphology of hydration products. The results show that most inert phase in BOF slag can be converted into active minerals of C4AF and C2S through reasonable batching calculation and the amount of regulating agent. The formation of C4AF and C2S in modified BOF slag is better, and a small amount of MgO is embedded in the white intermediate phase, but C3S is not detected. With the increase in the CaO/SiO2 ratio in raw materials, the CaO/SiO2 ratio of calcium silicate minerals in modified BOF slag increases, the contents of f-CaO are less than 1.0%, and the activity index improves. Compared with the BOF slag, the activity index and exothermic rate of modified BOF slag improved obviously, and the activity index of 90 days is close to 100%. With the increase in modified BOF slag B cement, the flexural strength decrease; however, the capability of resisting sulfate corrode is improved due to the constant formation of a short rod-like shape ettringite in Na2SO4 solution and the improvement of the structure densification of the hydration products.

scholarly journals Geotechnical Properties and Microstructure of Lime-Fly Ash-Phosphogypsum-Stabilized Soil

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Tebogo Pilgrene Mashifana ◽  
Felix Ndubisi Okonta ◽  
Freeman Ntuli
Keyword(s):  
Fly Ash ◽  
Expansive Soil ◽  
Basic Oxygen Furnace ◽  
Geotechnical Properties ◽  
Magnesium Silicide ◽  
Engineering Properties ◽  
Basic Oxygen ◽  
Basic Oxygen Furnace Slag ◽  
Phosphogypsum Waste ◽  
Furnace Slag

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.

Basic oxygen furnace slag: Review of current and potential uses

2020 ◽  
Vol 149 ◽  
pp. 106234 ◽  
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

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

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 6 ◽  
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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