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Computers and Concrete Volume 11, Number 1, January 2013 , pages 39-49 DOI: https://doi.org/10.12989/cac.2013.11.1.039 |
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Hydration and time-dependent rheology changes of cement paste containing ground fly ash |
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Wei Chen and Hao Huang
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| Abstract | ||
| The use of ground fly ash in concrete can increase the risk of slump loss due to the drastic surface change of the particles after the grinding treatment and the accelerated reaction compared to the untreated ash. This study is aimed at the early age hydration and time-dependent rheology changes of cement paste containing ground fly ash. An original fly ash is ground into different fineness and the hydration of cement paste containing the ground fly ash is monitored with the ultrasound propagation method. The zeta potentials of the solid particles are measured and the changes of rheological parameters of the cement pastes with time are analyzed with a rheometer. A particle packing model is used to probe packing of the solid particles. The results show that the early age hydration of the paste is strongly promoted by replacing Portland cement with fly ash up to 30 percent (by mass), causing increase of the yield stress of the paste. The viscosity of a paste containing ground fly ash is lower than that containing the untreated ash, which is explained by the denser packing of the solid particles. | ||
| Key Words | ||
| hydration; ground fly ash; rheology; packing | ||
| Address | ||
| Wei Chen: State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Luoshi Road 122, Wuhan, 430070, P.R. China; Hao Huang: School of Materials Science and Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, 430070, P.R. China | ||