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RESEARCH PRODUCT
Retention of alkali ions by hydrated low-pH cements: Mechanism and Na+/K+ selectivity
T. T. H. BachJ. HaasIsabelle PochardFabien FrizonC. Cau Dit CoumesAndré NonatE. Chabassubject
Cementchemistry.chemical_classificationMaterials scienceSilica fumeSodiumPotassiumInorganic chemistrytechnology industry and agriculturechemistry.chemical_elementBuilding and ConstructionPozzolanAlkali metallaw.inventionPortland cementchemistrylawGeneral Materials ScienceCounteriondescription
Low-pH cements, also referred to as low-alkalinity cements, can be designed by replacing significant amounts of Portland cement by pozzolanic materials. Their pore solution is characterized by a pH near 11, and an alkali concentration much lower than that of Portland cement. This work investigates the retention of sodium and potassium by a hydrated low-pH cement comprising 60% Portland cement and 40% silica fume. It is shown that sorption of potassium is higher than that of sodium and mainly results from counterion charge balancing of the C-S-H negative surface charge. To explain the greater retention of potassium compared to sodium, it is postulated that potassium, unlike sodium, may enter the interlayer of C-S-H to compensate the negative charges in the interlayer, in addition to the external surfaces. This assumption is supported by structural characterization of C-S-H using X-ray diffraction.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2013-09-01 | Cement and Concrete Research |