Study on Microstructure and Rheological Properties of Cement-Chemical Admixtures-Water Dispersion System at Early Stage by Yanrong Zhang

Author:Yanrong Zhang
Language: eng
Format: epub
Publisher: Springer Singapore, Singapore

With the incorporation of polymer latexes with particle size of 200–300 nm, the initial fluidity of FCPs declines at first and then increases to the maximum at the critical dosage of polymer latexes. It is supposed that at low L/C (<3%), low coverage on the cement surface facilitates the formation of a large amount of flocculated structures. With further addition of latexes, more coverage of latex particles on cement surface brings about better dispersion of cement grains because of the neutralization of the heterogeneous charge distribution of original cement grains and hence an increment of the initial fluidity. The maximum initial fluidity is respectively achieved at 9% L1 and 12% L2. Beyond the critical dosages, the further addition of latex particles causes the decrease of the initial fluidity, which originates from the increased content of solid phase constituting both cement grains and polymer particles, namely the filling effects of polymer latexes. On the other hand, higher dosages of latexes are beneficial to the fluidity retention of FCPs. Compared to the FCPs with latex L2, the ones with latex L1 show stronger fluidity retention over elapsed time.

A higher temperature brings about a decrease in the initial fluidity for all the FCPs containing latexes in most cases, and the impacts of temperature are strengthened as the dosage of L1 increases due to its demulsification at elevated temperatures. By contrast, for the FCPs with latex L2, the impact of temperature on initial fluidity is weakened at high dosages, which may be related to its lower film formation temperature. The fluidity retention of FCPs obviously decreases at elevated temperatures, and the effects of temperature gradually descend with the growth of L/C because of the stronger retardation effects of latexes on cement hydration at higher dosages.(3)Cement-Asphalt-Water system

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