| 2. |
- Sun, Hongfang, et al.
(författare)
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Synthesis and Properties of Red Mud-Based Nanoferrite Clinker
- 2019
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Ingår i: Journal of Nanomaterials. - : Hindawi Limited. - 1687-4129 .- 1687-4110. ; 2019
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Tidskriftsartikel (refereegranskat)abstract
- Red mud, an industrial waste obtained from alumina plants, is usually discharged into marine or disposed into a landfill polluting the surrounding water, atmosphere, and soil. Thus, disposal of red mud is an environmental concern and it should be recycled in an effective way. Since red mud consists of iron- and aluminum-rich phases, it can potentially be processed into cementitious material and can be used for a construction purpose. This research investigated the synthesis of nanoferrite (NF) clinker by using red mud as a raw material through chemical combustion technology for potential use in cement-based composite. Before the synthesis of NF, red mud was characterized by using XRF, XRD, and SEM techniques. From characterization results, the stoichiometric ratio of raw materials was calculated and experimentally optimized. The sample was then tested at various temperatures (815, 900, 1000, and 1100 degrees C) to find the optimum synthesis temperature. Finally, the hydraulic activity of NF was verified and the contribution to mechanical properties was determined by replacing cement with NF at various substitution levels (0, 5, 10, and 20wt%). Test results showed that the optimum condition for the synthesis of NF was found when the ratio of CaCO3/red mud was 1.5 and the sintering temperature was 815 degrees C. The synthesized NF had an average diameter of 300nm, and the main composition was brownmillerite (C(4)AF) with distinct hydraulic reaction. When NF was used as a substitute of Portland cement in mortar, the flexural strength with a 5% replacement level improved by 15%. Therefore, it can be concluded that the synthesis of NF provides an alternative approach to recycle red mud and could significantly help in reducing environmental pollution.
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| 3. |
- Zhang, Jianchao, et al.
(författare)
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Investigating the influence of fly ash on the hydration behavior of cement using an electrochemical method
- 2019
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Ingår i: Construction and Building Materials. - : Elsevier BV. - 0950-0618. ; 222, s. 41-48
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Tidskriftsartikel (refereegranskat)abstract
- © 2019 Elsevier Ltd Fly ash is an industrial by-product that is widely used in the cement industry. Traditional methods used to investigate the influence of fly ash on the hydration behavior of cement are destructive and cannot accomplish a continuous tracing of the hydration process. In this study, the influence of fly ash incorporation on the hydration process of cement is evaluated using measured electrochemical data obtained from the electrochemical impedance spectroscopy approach. A novel equivalent circuit model that considers the electrochemical characteristics of cement during the hydration process is proposed to investigate the electrochemical property of the blended cement. The resistance parameter of the model, Rct1, was found to have a positive correlation with hydration degree and compressive strength during hydration. With this parameter, the method can be used to non-destructively trace and characterize the effects of fly ash incorporation on the cement hydration process.
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