Cement Recycling System Using Sodium Gluconate

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Title: Cement Recycling System Using Sodium Gluconate

Author(s): Daiki Atarashi, Yutaka Aikawa, Yuya Yoda, Masahiro Miyauchi, and Etsuo Sakai

Publication: Special Publication

Volume: 302

Issue:

Appears on pages(s): 437-448

Keywords: sludge water; sodium gluconate; set retarder; rate of heat liberation; heat liberation

Date: 6/1/2015

Abstract:
The objective of this study was to establish a recycling system for cement sludge by hydration control and an evaluation of the residual cement content of sludge. The adsorption behavior of sodium gluconate on cementitious materials was clarified in this study. The saturated absorption behavior between sodium gluconate and alite follows a Langmuir adsorption isotherm. The delayed hydration time depends on the concentration of residual sodium gluconate. When the residual concentration of sodium gluconate was over 0.018–0.020 mass%, cement hydration did not proceed. The relationship between the heat liberation after 1 day and the amount of non-hydrated alite as calculated by X-ray diffractometry is linear. The amount of non-hydrated alite can be estimated by using calorimetric data. Finally, the amount of non-hydrated alite in sludge water can be estimated by using calorimetric data, magnesium hydrate hexahydrate (Mg(NO3)2·6H2O).