Fly ash as an assemblage of model Ca–Mg–Na-aluminosilicate glasses

Durdzinski, Pawel; Snellings, Ruben; Dunant, Cyrille F.; Haha, Mohsen Ben; Scrivener, Karen

doi:10.1016/j.cemconres.2015.08.005

Cited by 118 publications

(61 citation statements)

References 22 publications

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“…The dissolution of the glass depends on the glass structure (Mysen et al 1982;Moesgaard et al 2010). The results shown in (Durdziński et al 2015) represent a trend towards higher reactivity in cement paste with increasing glass structure disorder. This suggest that in the here investigated system, the increase of Al 2 O 3 content from 8 to 12 % initially has a disordering effect on the glass structure, while with further increase this effect is not pronounced.…”

Section: Hydration Of Synthetic Mixesmentioning

confidence: 94%

Effect of Slag Reactivity Influenced by Alumina Content on Hydration of Composite Cements

Kucharczyk

Deja

Zając

2016

ACT

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Journal of Advanced AbstractThis work investigates the role of alumina content in the slag and presence of limestone in composite cement on the hydration and compressive strength evolution of composite cement. A coupled experimental and modeling approach was applied. Increasing Al 2 O 3 content of slag from 8 % to 12 % has pronounced impact on slag kinetics while further increase from 12 % to 16 % has a limited effect. However, this increase affects the hydrates assemblage across the whole compositional range investigated; the composition of the C-S-H phase and hydrotalcite is modified. Additionally the AFm and AFt phases content changes. Presence of limestone has a pronounced impact on the hydration, being more pronounced for the slags of high alumina content. This is related to the formation of hemi-and mono-carbonate and stabilization of ettringite. Despite of these changes, the pore size distribution is similar among the investigated cements. Thermodynamic modelling matches favorably the experimental data and enables calculating the evolution of the pore volume over the time. A relationship between calculated porosity and compressive strength is proposed and verified. This relationship shows that all hydrated phases have a similar impact on compressive strength and the strength is mainly related to the pore volume.

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Section: Hydration Of Synthetic Mixesmentioning

confidence: 94%

Effect of Slag Reactivity Influenced by Alumina Content on Hydration of Composite Cements

Kucharczyk

Deja

Zając

2016

ACT

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“…Reasonable correlations can be found for SCMs from one source, however Lang [25] reported that for a large dataset of 370 blast furnace slag cement it is impossible to calculate the strength with sufficient precision, based only on the chemical composition and glass content of the slag. The composition of the amorphous fraction of some SCMs such as fly ash may be highly heterogeneous and of strongly contrasting reactivity [26]. There's a strong correlation between glass composition and reactivity [27] and this will interfere with obtaining a predictive relationship between total amorphous fraction and reactivity or strength contribution for a wide range of SCMs.…”

Section: Scm Propertiesmentioning

confidence: 98%

Rapid screening tests for supplementary cementitious materials: past and future

2015

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Rapid screening tests for supplementary cementitious materials (SCMs) have been in use for over 150 years. Over the years a multitude of methods have been put forward to predict the strength development of SCM blended mortars and concrete. This paper summarizes and rationalizes the main approaches and then applies them to a selection of materials that cover a broad range of SCMs, both pozzolanic and hydraulic. Included are siliceous fly ash, blast furnace slag, natural pozzolan, metakaolin and an inert quartz filler. The selected test methods are the Chapelle test, the Frattini test, active silica and alumina extractions, a dissolution rate test, and a new calorimetry-based test. The results are compared, interpreted and discussed in view of their aim of predicting the compressive strength development. Finally, a new test method is proposed that relates the cumulative heat of the SCM reaction in a simplified model system to the compressive strength development in standardized mortars. The new method is practical, repeatable and applicable to a wide range of SCMs (both pozzolanic and hydraulic), it furthermore reduces the experiment duration by a factor of 10 and correlates well to the compressive strength development of blended cement mortar bars.

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“…The peak position of the glassy phase has been shown to vary with the composition of the glassy phase. In glass with high calcium content, the peak in the XRD spectrum has been shown to occur at higher 2θ angles . In this case, the peaks of the amorphous reaction product may overlap significantly with the peak of the glassy phase.…”

Section: Findings and Conclusionmentioning

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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Fly ash as an assemblage of model Ca–Mg–Na-aluminosilicate glasses

Cited by 118 publications

References 22 publications

Effect of Slag Reactivity Influenced by Alumina Content on Hydration of Composite Cements

Effect of Slag Reactivity Influenced by Alumina Content on Hydration of Composite Cements

Rapid screening tests for supplementary cementitious materials: past and future

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

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