The Relationship between Retention Stability and Chemical Structure of PCE

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Title: The Relationship between Retention Stability and Chemical Structure of PCE

Author(s): F. Göller, S. Dikty, and D. Hamada

Publication: Special Publication

Volume: 262

Issue:

Appears on pages(s): 249-260

Keywords: adsorption; cement; polycarboxylate superplasticizer; retention stability; slump-loss-controlling agent; workability.

Date: 10/1/2009

Abstract:
The retention performance of concrete is highly influenced by external parameters such as cement type, water content, materials, temperature and so on which sometimes appears to be a problem for ready-mixed concrete producers. The influences of the molecular structure and functional groups of PCE superplasticizers on the retention performance in terms of external changes were studied. In the course of our investigations we focussed on the slump-loss-controlling agent with release compound (SLCA) and a common PCE with shorter polyethylene oxide chains. It was found that the retention ratio of the SLCA was much less affected by changes of temperature and mixing time, but the retention ratio of both superplasticizers was influenced by change of w/c. Superplasticizer SLCA with an additional release compound showed a much higher adsorption increase over time than the common selected PCE. The importance of the chemical structure of polycarboxylated superplasticizer to the retention stability could be related to the adsorption mechanism. At the same time a lower retardation effect on the setting time could be observed for the SLCA superplasticizer.