Calcium Nitrate Counteracting PCE Superplasticizer Retardation

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Title: Calcium Nitrate Counteracting PCE Superplasticizer Retardation

Author(s): Karel Lesage, Ozlem Cizer, Geert De Schutter, Bram Desmet, John Vantomme, and Lucie Vandewalle

Publication: Special Publication

Volume: 288

Issue:

Appears on pages(s): 1-13

Keywords: calcium nitrate; hydration accelerations; superplasticizer retardation.

Date: 9/14/2012

Abstract:
Calcium nitrate (CN) has been used as a cement hydration accelerator in varying dosages in order to explore its potential to compensate hydration retardation caused by a polycarboxylic ether (PCE) superplasticizer. The initial setting time, obtained from Vicat needle penetration tests, was found to decrease for increasing CN dosage until 4 percent of the cement mass was added. For dosages beyond this amount, the initial setting time slightly increased. The detected alite and aluminate hydration products appeared to have an influence on the structure evolution during setting. It is assumed that the AFt needles destruct the C-S-H network, which could lead to lower needle penetration resistance.