Quantification of the Extent of Reaction of Metakaolin-Based Geopolymers Using X-Ray Diffraction, Scanning Electron Microscopy, and Energy-Dispersive Spectroscopy

Williams, Ross P.; Hart, Robert D.; Riessen, Arie van

doi:10.1111/j.1551-2916.2011.04410.x

Cited by 112 publications

(45 citation statements)

References 35 publications

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“…The PONCKS method was recently applied to the quantification of the degree of reaction of metakaolin in alkali activated systems [80], and in the quantification of C-S-H in the early hydration of alite [8]. The precision and accuracy of the PONKCS approach in the quantification of amorphous SCM (blast furnace slag and metakaolin) levels in blended cements was assessed recently in synthetic model mixes [72].…”

Section: Xrdmentioning

confidence: 99%

TC 238-SCM: hydration and microstructure of concrete with SCMs

Scrivener¹,

et al. 2015

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This paper is the work of working group 2 of the RILEM TC 238-SCM. Its purpose is to review methods to estimate the degree of reaction of supplementary cementitious materials in blended (or composite) cement pastes. We do not consider explicitly the wider issues of the influence of SCMs on hydration kinetics, nor the measurement of degree of reaction in alkali activated materials. The paper categorises the techniques into direct methods and indirect methods. Direct methods attempt to measure directly the amount of SCM remaining at a certain time, such as selective dissolution, microscopy combined with image analysis, and NMR. Indirect methods infer the amount of SCM reacted by back calculation from some other measured quantity, such as calcium hydroxide consumption. The paper first discusses the different techniques, how they operate and the advantages and limitations along with more details of case studies on different SCMs. In the second part we summarise the most suitable approaches for each SCM, and the paper finishes with conclusions and perspectives for future work.

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Section: Xrdmentioning

confidence: 99%

TC 238-SCM: hydration and microstructure of concrete with SCMs

Scrivener¹,

et al. 2015

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“…An evaluation of the influence of process variables and the efficiency of fly ash as a cement replacement requires methods for assessing the degree of reaction of fly ash in a binary blend. Different methods for determining the degree of reaction of fly ash have been developed including, selective acid dissolution, [4][5][6][7][8][9][10][11][12] NMR analysis, 13,14 backscattered electron imaging, 15,16 Scanning Electron Microscopy (SEM) with energy dispersive spectroscopy (EDS), 17,18 and mass balance. 19 Among all the methods, selective dissolution is the most widely used method to determine the reaction of fly ash.…”

Section: Introductionmentioning

confidence: 99%

Method for Direct Determination of Glassy Phase Dissolution in Hydrating Fly Ash‐Cement System Using X‐ray Diffraction

Singh

Subramaniam

2016

J. Am. Ceram. Soc.

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A method for quantitative X‐ray diffraction analysis is developed for direct determination of the glassy phase content of fly ash in a hydrating binary blend of cement and low‐calcium, siliceous fly ash. The intensity contributions of the unhydrated glassy phase of fly ash and the amorphous reaction products to the intensity pattern of the total amorphous phase in the hydrating binary blend are obtained by decomposition of the total intensity signature as a sum of component pseudo Voigt (PV) peaks. An experimental program involving binary blends with three different low calcium siliceous fly ashes and two different curing temperatures is reported. The centers of the component PV peaks of the fly ash glassy phase fitted to the overall intensity pattern are found to be invariant. The glassy phase content of hydrating binary blends determined from the XRD method were found to agree well with the values obtained from a selective dissolution method.

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“…However, the amorphous (non-crystalline) phases can also be quantified [3], allowing kinetics of amorphous phase(s) dissolution/growth to be quantified [4,5]. …”

Section: Introductionmentioning

confidence: 99%

The First 20 Hours of Geopolymerization: An in Situ WAXS Study of Flyash-Based Geopolymers

Williams

Riessen

2016

Materials

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This study followed the first 20 h of flyash geopolymerization at 70˝C using time resolved Wide Angle X-ray Scattering (WAXS). The extent of dissolution of the amorphous phase of the flyash was determined to range from 29% to 54% for the different formulations trialed. The dissolution rate of the flyash significantly reduced after the first 5 h for all samples. During the formation stage of the geopolymer there were significant temporal variations in the chemistry of the dissolved solution due to the rate of flyash dissolution, with a relative standard deviation of 20%, 57% and 24% for the Si/Al, Na/Al and H/Si ratios, respectively. Utilizing the Power Law, scattering in the low angle region of the WAXS pattern combined with the geopolymer peak area yielded a measure which correlated with the compressive strength-providing a new method to measure the flyash dissolution and geopolymer formation processes independently. The evolution of several zeolite-like phases was followed, noting there are different formation mechanisms involved even within the same sample. Four samples were examined with compressive strengths ranging from 14(2)-50(9) MPa, each was synthesized with flyash from Collie Power Station (Western Australia) activated with sodium silicate solution of varying concentrations.

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Quantification of the Extent of Reaction of Metakaolin-Based Geopolymers Using X-Ray Diffraction, Scanning Electron Microscopy, and Energy-Dispersive Spectroscopy

Cited by 112 publications

References 35 publications

TC 238-SCM: hydration and microstructure of concrete with SCMs

TC 238-SCM: hydration and microstructure of concrete with SCMs

Method for Direct Determination of Glassy Phase Dissolution in Hydrating Fly Ash‐Cement System Using X‐ray Diffraction

The First 20 Hours of Geopolymerization: An in Situ WAXS Study of Flyash-Based Geopolymers

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