Elucidation of the role of calcium lignosulfonate in the hydraton of C3A = Eclaircissement du rôle du lignosulfonate de calcium dans l'hydration du C3A

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ConferenceProceedings of the 7th International Congress on the Chemistry of Cement: 1980, Paris, France
Pages535540; # of pages: 6
Subjectadsorption; hydration; retardants; hydrated cement; tricalcium aluminate; hexagonal calcium aluminate; cubic calcium aluminate hydrate; calcium lignosulfonate; reactions; hydration retardation by lignosulfonate; Concrete
AbstractAdsorption-desorption isotherms were obtained by exposing tricalcium aluminate (C[3]A), hexagonal calcium aluminate (C[ 4]AH[13]-C[2]AH[8]) and cubic aluminate hydrate (C[3]AH[6]) to calcium lignosulfonate (CLS) solutions in water or dimethyl sulfoxide. In the non-aqueous medium C[3]A and C[3] AH[6] adsorb little, if any, lignosulfonate; the hexagonal phase adsorbs about 2.2% CLS. In an aqueous medium containing large amounts of CLS, C[3]A forms a basic CLS complex that is insoluble in water. Scanning loops in the isotherms for the hexagonal aluminate-CLS-H[2]O system show complete irreversibility with an adsorption of 10% at an equilibrium concentration of 0.10% CLS. A rapid irreversible adsorption of 2.05% CLS occurs in the C[3]AH[6]- CLS-H[2]O system. The C[3]A, C[4]AH[13]-C[2]AH[8] and C[3] AH[6] phases act as sinks for CLS in the hydration of C[3]S containing CLS; the hydration of C[3]S that is completely inhibited in the presence of 0.8% CLS can be restored by the addition of these aluminate phases. The relative effectiveness with which the addition of 5% of these additives counteracts the inhibitive influence of CLS is in the order of C[3]A>C[4]AH[13]-C[2]AH[8]>C[3]AH[6]. Both Ca and Na-lignosulfonates containing no sugar behave in a manner similar to the commercial lignosulfonate in retarding the hydration of C[3]A.
Publication date
AffiliationNRC Institute for Research in Construction; National Research Council Canada
Peer reviewedYes
NRC number20075
NPARC number20375200
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Record identifiere74837c9-540d-484c-a8d5-ca549219fc87
Record created2012-07-23
Record modified2016-05-09
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