Composition, morphology and nanostructure of C-S-H in white Port-land cement pastes hydrated at 55 degrees C

resumo

The C-S-H present in water- and alkali-activated hardened pastes of white Portland cement hydrated at 55 degrees C has been characterized. The mean length of the-aluminosilicate anions in the C-S-H was similar in both systems and increased with age. Inner product C-S-H generally had a fine scale, homogeneous morphology. Outer product C-S-H was generally fibrillar with water, and foil- or lath-like with alkali. There were some regions of C-S-H with coarse morphology. It was not possible to determine the chemical composition of C-S-H using the SEM; TEM-EDX was necessary. The C-S-H formed in the alkali-activated paste had a lower mean Ca/(Al+Si) ratio than that formed with water, which was offset by a larger quantity of calcium hydroxide. The potassium in the KOH-activated paste was present either within the C-S-H structure charge balancing the substitution of Al3+ for Si4+, or adsorbed on the C-S-H charge balancing sulfate ions. (C) 2007 Elsevier Ltd. All rights reserved.

palavras-chave

TRICALCIUM SILICATE; DICALCIUM SILICATE; HARDENED PASTES; TEMPERATURES; GEL; MICROSTRUCTURE; PHASES; SLAG; METAKAOLIN; MODELS

categoria

Construction & Building Technology; Materials Science

autores

Girao, AV; Richardson, IG; Porteneuve, CB; Brydson, RMD

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