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- Björnström, Joakim, 1976, et al.
(author)
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Antagonistic effect of superplasticizer and colloidal nano-silica in the hydration of Alite and Belite pastes
- 2007
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In: Journal of Materials Science. - : Springer Science and Business Media LLC. - 0022-2461 .- 1573-4803. ; 42:11, s. 3901-3907
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Journal article (peer-reviewed)abstract
- The dependence on the hydration rate for Alite and Belite clinker phases in the presence of a polycarboxylate superplasticizer PC SP upon addition of colloidal nano-silica CNS were monitored by means of Diffuse Reflectance Infrared spectroscopy DR-FTIR. Spectral signatures of clinker dissolution and product formation were acquired for both materials. The rates for the build-up of product vibrational band intensities were found to depend sensitively on addition of CNS. The hydration product was proposed to be calcium-silicate-hydrate C-S-H. Details in the spectral signatures were found to differ. Quantum chemical calculations were employed and found to be consistent with the interpretation that small clusters dominate the Alite C-S-H spectrum, whereas the Belite C-S-H spectrum results from extended polymers.
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- Herbert, Roger, 1966-, et al.
(author)
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Barrier system for the treatment of nitrogen effluents from the Malmberget iron mine
- 2009
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In: <em>Proceedings, Securing the Future</em>. Skellefteå, Sweden.
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Conference paper (peer-reviewed)abstract
- At the Malmberget iron mine in northern Sweden, nitrogen from undetonated explosives is discharged from the mine with process water. After passing through a settling pond, excess process water is discharged to the Linaälv River via a spillway. Because of the risk for eutrophication in rivers and coastal areas downstream, it is necessary to decrease the N levels in the effluent waters. This study presents the results from laboratory column experiments under water – saturated conditions, conducted at room temperature and 5oC, which will be used in the design of a pilot-scale barrier system. The columns were filled with a reactive substrate consisting of sawdust and activated sewage sludge. The results of the room temperature experiments demonstrated that nitrate removal efficiency was >95% for flow rates < 341 liters d-1 m-3 reactive mixture. However, at flow rates of ~700 liters d-1 m-3 reactive mixture, nitrate removal efficiency decreased to ~64%. Tracer experiments indicated an increasing degree of channeling in the columns as flow rate increased, thus leading to a reduction in removal efficiency. Apparent denitrification rates were estimated to 2.8 -9.3 g N d-1 m-3 and 2.2 g N d-1 m-3 at room temperature and 5oC, respectively.
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