Thermodynamic Modeling of Portland Cement—Metakaolin—Limestone Blends

Kunther, Wolfgang; Dai, Zhuo

doi:10.1007/978-94-017-9939-3_18

Cited by 5 publications

(7 citation statements)

References 6 publications

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“…The pozzolanic reactivity of calcined natural clays was shown to increase with increasing amount of kaolinite (François Avet, et al, 2016;Chakchouk, et al, 2006). The coupled substitution of cement with calcined clay and limestone was also investigated (Antoni, Rossen, Martirena, & Scrivener, 2012;Scrivener, 2018a, 2018b;Bishnoi and Maity, 2018;Cancio Díaz et al, 2017;Favier, Zunino, Katrantzis, & Scrivener, 2018;Kunther, Dai, & Skibsted, 2015;Nied, Stabler, & Zajac, 2015;Karen Scrivener, Martirena, Bishnoi, & Maity, 2017;Tironi, et al, 2015). It was found that up to 45% substitution of cement with a 2:1 blend of metakaolin and limestone gave better compressive strength than the pure reference cement system (Antoni, et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Calcareous smectite clay as a pozzolanic alternative to kaolin

Danner

Norden²,

Justnes

2019

European Journal of Environmental and Civil Engineering

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The hydration of cement pastes with addition of a kaolinite rich clay (Clay A) and a calcareous smectite rich clay (Clay B) was investigated with isothermal calorimetry, in-situ XRD, PXRD, TGA and EPMA. Portland cement was replaced by 20, 35 and 50 weight% calcined clay in cement pastes and mortars. Both clays showed good pozzolanic reactivity. However, clay A having a higher amount of metakaolin and higher specific surface was more reactive in terms of CH consumption and mortar strength development. 50% replacement of PC by calcined Clay A resulted in increased 28 day compressive strength while mortars with 50% calcined Clay B showed almost equal 28 day compressive strength compared to the reference. With increasing addition of calcined clay, the second aluminate reaction (formation of AFm phase) of cement hydration was accelerated and the cement pastes became under sulphated. This resulted in a stronger and earlier sulphate depletion peak, especially in pastes with calcined Clay A. Due to 3% calcite in the used cement the main hydration product found was carboaluminate hydrate. The favoured formation of carboaluminate hydrate stabilised ettringite in the cement pastes.

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Section: Introductionmentioning

confidence: 99%

Calcareous smectite clay as a pozzolanic alternative to kaolin

Danner

Norden²,

Justnes

2019

European Journal of Environmental and Civil Engineering

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“…Ternary blends of cement, metakaolin and limestone have been investigated by many authors (Antoni et al, 2012;Avet and Scrivener, 2018a, b;Bishnoi and Maity, 2018;Cancio Díaz et al, 2017;Favier et al, 2018;Kunther et al, 2015;Nied et al, 2015;Scrivener et al, 2017;Tironi et al, 2015). However, the role of calcium carbonate in raw clays (before calcination) without kaolinite has been paid little attention to.…”

Section: Introductionmentioning

confidence: 99%

Characterisation of calcined raw clays suitable as supplementary cementitious materials

Danner

Norden

Justnes

2018

Applied Clay Science

111

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The potential use of two raw clays (Clay A: kaolin; Clay B: calcareous montmorillonite) as supplementary cementitious material (SCM) in blended cements was investigated. Cement replacement in mortars by 20% calcined Clay A and Clay B resulted in a considerable 28 day compressive strength improvement. The pozzolanic reactivity of Clay A and B is explained by characterization of the structural changes upon calcination with XRD, ICP-MS, FT-IR, 27Al-NMR, Mössbauer spectroscopy and SEM. At the temperature giving highest pozzolanic reactivity, kaolinite and montmorillonite were completely dehydroxylated, while calcite from Clay B was not completely decomposed. FT-IR, 27Al-NMR and Mössbauer spectroscopy revealed considerable structural deformations of kaolinite in Clay A and montmorillonite in Clay B resulting in an amorphous, reactive state. Oxidation of iron in Clay B during calcination contributed to strong distortions of the octahedral sheet in the montmorillonite structure. Additionally, the formation of a glass phase due to reaction of coccoliths (CaCO3) and montmorillonite was observed.

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“…These calculations can be used to estimate the extent of the reaction, with the equations shown in Equations ( 4)-( 6) [40,111]. Combining kinetic calculations with GEMs effectively improves the accuracy of thermodynamic calculations, and experimental results fit well with simulation results [123]. Figure 11 shows the kinetic calculations for ternary systems, which typically focus on the generation of hydration products at different reaction ages.…”

Section: Hydration Kineticsmentioning

confidence: 99%

“…Further research was conducted to investigate its effect on hydration kinetics and its role in ternary systems [30,40]. Kunther et al [111,123] used 27 Al MAS NMR and 29 Si MAS NMR to determine the products at different reaction ages based on GEMS. They optimized the results of the thermodynamic tests and proposed to carry out the reaction kinetics calculations of the components in the ternary system.…”

Section: Hydration Kineticsmentioning

confidence: 99%

Recent Developments on the Effects of Micro- and Nano-Limestone on the Hydration Process, Products, and Kinetics of Cement

Li,

Cao

2024

Materials

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Limestone is commonly used in cement concrete due to its unique nature and type. It has physical effects (nucleation effect and dilution effect) and chemical effects on the hydration process of cement. This paper reviews the effects of three representative limestone materials on the hydration process, hydration products, and hydration kinetics. In the hydration process, the reaction was delayed by limestone powder with a particle size larger than 20 μm and calcium carbonate whiskers due to their dilutive effect. On the other hand, limestone powder with a particle size smaller than 20 m and calcium carbonate nanoparticles facilitated the reaction through nucleation and chemical effects. Limestone has a similar effect on hydration products, promoting the production of C-S-H through nucleation. The mechanism of action for this nucleation effect depends on the differences in crystalline form and particle size of the three types of micro- and nano-calcium. Chemical effects impact the amount of AFt produced, with the generation of new products being the main reaction influenced by the limestone admixture.

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Thermodynamic Modeling of Portland Cement—Metakaolin—Limestone Blends

Cited by 5 publications

References 6 publications

Calcareous smectite clay as a pozzolanic alternative to kaolin

Calcareous smectite clay as a pozzolanic alternative to kaolin

Characterisation of calcined raw clays suitable as supplementary cementitious materials

Recent Developments on the Effects of Micro- and Nano-Limestone on the Hydration Process, Products, and Kinetics of Cement

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