Intercalation of Polycarboxylate Superplasticizers into C3A Hydrate Phases

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Title: Intercalation of Polycarboxylate Superplasticizers into C3A Hydrate Phases

Author(s): J. Plank, Z. Dai, N. Zouaoui, and D. Vlad

Publication: Special Publication

Volume: 239

Issue:

Appears on pages(s): 201-214

Keywords: cement hydration; intercalation; polycarboxylate; superplasticizer; tricalcium aluminate

Date: 10/1/2006

Abstract:
Pure C3A hydrates under formation of layered phases (e.g. C4AH19 and C2AH8) which quickly convert to the cubic phase C3AH6. In presence of polycarboxylate (PC) superplasticizers during C3A hydration, intercalation of the PC molecule into the layered calcium aluminum hydrate occurs. The resulting organo mineral phases Ca-Al-PC-LDHs are very stable. They were characterized by powder XRD, elemental analysis, IR spectroscopy and TEM microscopy. XRD patterns show that with increasing side chain length (nEO) of PC, the distance (basal spacing) between the [Ca2Al(OH)6]+ layers increases. PCs with side chain lengths up to 45 ethylene oxide (EO) units intercalate well whereas a PC with 111 EO units no longer intercalates. Calculations indicate that the PC side chains mostly are compressed or tilted to fit in between the inorganic layers.