Portlandite solubility and Ca2+ activity in presence of gluconate and hexitols

Journal Article · Mon Nov 15 04:00:00 EST 2021 · Cement and Concrete Research

DOI:https://doi.org/10.1016/J.CEMCONRES.2021.106563· OSTI ID:23206207

Bouzouaid, Lina ^[1]; Lothenbach, Barbara ^[2]; Fernandez-Martinez, Alejandro ^[3]; Labbez, Christophe ^[1]

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1. ICB, UMR 6303 CNRS, Univ. Bourgogne Franche-Comté, FR-21000 Dijon (France)
2. Empa, Concrete & Asphalt Laboratory, Dubendorf (Switzerland)
3. Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD, IFSTTAR, ISTerre, 38000 Grenoble (France)

The current paper investigates the impact of gluconate, D-sorbitol, d-mannitol and D-galactitol on calcium speciation at high pH values by i) solubility measurements of portlandite (Ca(OH){sub 2}) and ii) potentiometric titration measurements of calcium salt solutions. Thermodynamic modelling was used to fit the chemical activities of Ca{sup 2+} and OH{sup −} ions and thus to determine the strength and kind of the different Ca-organic-hydroxide complexes. The strength of complex formation with Ca{sup 2+} decreases in the order gluconate ≫ sorbitol > mannitol > galactitol, which follows the same order as sorption on portlandite. Heteropolynuclear gluconate complexes with calcium and hydroxide dominate the Ca-speciation in the presence of portlandite, while for sorbitol ternary CaSorbOH{sup +} complexes were dominant under alkaline conditions. We expect that these results will help in better understanding the influence of gluconate and hexitols on the hydration of alite and Portland cement.

• OSTI ID: 23206207
• Journal Information: Cement and Concrete Research, Journal Name: Cement and Concrete Research Vol. 149; ISSN 0008-8846; ISSN CCNRAI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CALCIUM HYDROXIDES
CALCIUM IONS
PH VALUE
PORTLAND CEMENT
POTENTIOMETRY
SIMULATION
SOLUBILITY
SOLUTIONS
SORBITOL
THERMODYNAMIC ACTIVITY
THERMODYNAMICS