Thermodynamic properties of sodium aluminosilicate hydrate (N–A–S–H)

Walkley, Brant; Ke, Xinyuan; Hussein, Oday H.; Provis, John L.

doi:10.1039/d1dt02202d

Cited by 25 publications

(3 citation statements)

References 55 publications

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“…(Note that the sample was measured at room temperature after heat treatment in our previous investigation.) The broad scattering intensity at a Q value of ∼2.05 Å −1 in all samples at ambient temperature is indicative of the formation of a N−A−S(−H) gel, 54 the known reaction product of AAMK, 36 along with contributions from unreacted MK at ∼1.7 Å −1 . 55 Additionally, scattering from the capillary is noticeable in the diffraction pattern at ∼0.39 Å −1 .…”

Section: ■ Materials and Methodsmentioning

confidence: 88%

Nanostructural Evolution of Calcium-Containing Alkali-Activated Metakaolin During High Temperature Exposure

Alventosa,

White

2024

J. Phys. Chem. C

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Alkali-activated metakaolin (AAMK) is a known low CO 2 alternative material to ordinary Portland cement, where CO 2 emissions can be lowered even further via the use of reduced alkali concentration activators and moderate water-to-metakaolin ratios. We have previously shown that a relatively small amount of calcium hydroxide can be used (10 wt % replacement for metakaolin) to help offset the loss of ambient temperature performance associated with lowering the alkali concentration of the activator, specifically for silicate-based activators, without adversely compromising desired CO 2 emissions reductions. Here, the impacts of activator type (sodium silicate and sodium hydroxide), alkali concentration, and inclusion of calcium hydroxide on the high temperature phase transformations (up to ∼900 °C) occurring in AAMK are investigated using in situ synchrotron-based high-resolution X-ray diffraction and pair distribution function (PDF) analysis. High-resolution reciprocal space data reveal important insight on the evolution of minor crystalline phases, including those containing calcium. PDF analysis of the short-range order of the AAMKs shows temperature-induced changes to the sodium and calcium local bonding environments. After removal of crystalline contributions from the PDF data at high temperature, the residual PDFs provide new insight on the amorphous atomic arrangements present in the material and, together with identification of the calcium-containing crystalline phases, reveal the most likely location of the calcium atoms.

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Section: ■ Materials and Methodsmentioning

confidence: 88%

Nanostructural Evolution of Calcium-Containing Alkali-Activated Metakaolin During High Temperature Exposure

Alventosa,

White

2024

J. Phys. Chem. C

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“…[36][37][38] The predominant resonance centred at 56.8 ppm in the AAMK geopolymers is associated with fully polymerised tetrahedral Al. 25,39 Al 3+ replaces Si 4+ in SiO 4 tetrahedra to form negatively charged AlO 4 − tetrahedra balanced by Na + in N-A-S-H.…”

Section: Paper Dalton Transactionsmentioning

confidence: 99%

Structural composition of antibacterial zinc-doped geopolymers

Kang

2023

Dalton Trans.

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“…In the dissolution approach, the synthesized dry solid is dispersed in degassed water (by boiling) and stored in plastic bottles (HDPE or PTFE) [19,20,24]. The sealed bottles are then kept in suspension isothermally at several selected temperature points until the dissolution reaction reaches equilibrium as determined from statistically constant measurements of reaction products from sample aliquots measured over time [19,45,46]. The time for the dissolution reaction to reach equilibrium can vary with respect to the solid phase, temperature and solution conditions.…”

Section: Solubility Constantmentioning

confidence: 99%

Methods of incorporation of new reaction products in thermodynamic databases of cementitious systems

Zhu¹,

Juenger

Isgor³

et al. 2023

RILEM Tech Lett

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Strategic blending of supplementary cementitious materials (SCMs) into ordinary portland cement (OPC) helps reduce energy use and greenhouse gas emissions from concrete production. Expanding thermodynamic databases to include new reaction products from blended cements improves computational approaches used to understand the impact of blending SCMs with cement. Determination of thermodynamic parameters of cement reaction products based on temperature-dependent solubility is widely used in cement research; however, assumptions, limitations, and potential errors due to intercorrelation of the thermodynamic parameters in these calculation methods are rarely discussed. Here, methods for obtaining thermodynamic parameters are critically reviewed, including discussion of experimental validation. The discussion herein provides useful guidance to improve and validate the process of determining thermodynamic parameters of new reaction products from SCM-OPC reactions.

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Thermodynamic properties of sodium aluminosilicate hydrate (N–A–S–H)

Abstract: This study presents for the first time a systematic investigation of the thermodynamic properties of sodium aluminosilicate hydrate (N-A-S-H), through dissolution of pure synthetic N-A-S-H gels. Changes to the chemical...

Cited by 25 publications

References 55 publications

Nanostructural Evolution of Calcium-Containing Alkali-Activated Metakaolin During High Temperature Exposure

Nanostructural Evolution of Calcium-Containing Alkali-Activated Metakaolin During High Temperature Exposure

Structural composition of antibacterial zinc-doped geopolymers

Methods of incorporation of new reaction products in thermodynamic databases of cementitious systems

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