Action Mechanisms of Comb-Type Superplasticizers Containing Grafted Polyethylene Oxide Chains


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Title: Action Mechanisms of Comb-Type Superplasticizers Containing Grafted Polyethylene Oxide Chains

Author(s): E. Sakai, J. K. Kang, and M. Daimon

Publication: Special Publication

Volume: 195


Appears on pages(s): 75-90

Keywords: anhydrite; gypsum; hydration; superplasticizers

Date: 7/1/2000

In connection with environmental problems, the utilization of industrial materials waste, municipal refuse, sludge or its incineration ashes as raw materials for cement has recently begun. If their utilization amount increases in the future, it will result in the increase in aluminate phase. It is necessary to clarify the influence of superplasticizers on the hydration of aluminate phase. In addition, the fluidity of the cement paste which the sulfate ion content is high, is decreased by addition of comb-type superplasticizers. This is also closely related to initial hydration of cement. In order to clarify the action mechanisms of comb-type super-plasticizers, this paper discusses the influence of super-plasticizers on the early hydration of C,A-calcium sulfates by quantitative XRD compared with the case of naphthalene type superplasiticizer. Early hydration of C,A is accelerated by adding of comb-type super-plasticizers in C,A-calcium sulfates systems. In the case of comb-type superplasticizers, SO,“- contents in gel formed around C,A is decreased. It is necessary to control the early hydration reaction of aluminate phase in order to control the fluidity of the cement with comb-type superplasticizers.