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A platform for research: civil engineering, architecture and urbanism
Jarosite waste as a possible alternative to gypsum in Portland cement manufacture
In this paper, the possibility of using jarosite as a substitute for natural gypsum in cement production was investigated. The evaluation of the data of chemical analyses, X-ray diffraction analyses, measurements of setting time and compressive strengths showed that the substitution of gypsum by jarosite up to 80 % did not affect the properties of the cement mixtures produced within the framework of these investigations. However, 100% substitution by jarosite led a to shortening of both the initial and final setting times and to a significant decrease in 1 day compressive strengths values for PPC. The strength reduction could be due to a reduced initial hydration reaction rate and the correspondingly reduced liberation of portlandite and heat of hydration. This was corroborated by isothermal conduction calorimeter data. It is significant to note that even though jarosite alone contains and releases significant amounts of trace metal ions during leaching, these metals become fixed and immobilized in the hydrated cement silicate matrix after sufficient hydration time. TCLP studies indicate that the leaching rate of trace metal ions from cements containing jarosite is well within the safe US-EPA limits. This shows that jarosite has a promising potential to replace natural gypsum fully or partially in cement manufacture. However, further studies on the effect of long term hydration on leaching, durability and corrosion in concrete have to be carried out before this material can be used successfully as an alternative. Additionally, such investigations should consider the differing properties of clinker and cements. The outcome is expected to result in a possible major solution for a safe recycling of the hazardous jarosite precipitates released from zinc industries by developing non-hazardous products which can be used in building applications.
Jarosite waste as a possible alternative to gypsum in Portland cement manufacture
In this paper, the possibility of using jarosite as a substitute for natural gypsum in cement production was investigated. The evaluation of the data of chemical analyses, X-ray diffraction analyses, measurements of setting time and compressive strengths showed that the substitution of gypsum by jarosite up to 80 % did not affect the properties of the cement mixtures produced within the framework of these investigations. However, 100% substitution by jarosite led a to shortening of both the initial and final setting times and to a significant decrease in 1 day compressive strengths values for PPC. The strength reduction could be due to a reduced initial hydration reaction rate and the correspondingly reduced liberation of portlandite and heat of hydration. This was corroborated by isothermal conduction calorimeter data. It is significant to note that even though jarosite alone contains and releases significant amounts of trace metal ions during leaching, these metals become fixed and immobilized in the hydrated cement silicate matrix after sufficient hydration time. TCLP studies indicate that the leaching rate of trace metal ions from cements containing jarosite is well within the safe US-EPA limits. This shows that jarosite has a promising potential to replace natural gypsum fully or partially in cement manufacture. However, further studies on the effect of long term hydration on leaching, durability and corrosion in concrete have to be carried out before this material can be used successfully as an alternative. Additionally, such investigations should consider the differing properties of clinker and cements. The outcome is expected to result in a possible major solution for a safe recycling of the hazardous jarosite precipitates released from zinc industries by developing non-hazardous products which can be used in building applications.
Jarosite waste as a possible alternative to gypsum in Portland cement manufacture
Jarosit-Abfall als mögliche Alternative zu Gips bei der Herstellung von Portlandzement
Suresh, K. (author) / Sharma, J.M. (author) / Kuchya, M. (author) / Kashyap, I.P. (author) / Pandey, S.P. (author) / Chowdhury, S. (author)
Cement International ; 10 ; 90-97
2012
8 Seiten, 6 Bilder, 6 Tabellen, 27 Quellen
Article (Journal)
English , German
Utilisation of by-product jarosite in the manufacture of ordinary Portland cement
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