Calcined kaolinite–bentonite clay blends as supplementary cementitious materials

Taylor-Lange, Sarah C.; Lamon, Emily L.; Riding, Kyle A.; Juenger, Maria

doi:10.1016/j.clay.2015.01.025

Cited by 138 publications

(64 citation statements)

References 55 publications

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“…Moreover, while the physical and chemical properties of metakaolin in mortars and concrete have been the subject for a large number of studies [11,12] (and references therein), the potential of interstratified 2:1 clays has not been fully explored. Several studies have examined illite [13], smectite [14][15][16], and a set of clays including mixtures of these 2:1 clays [9,10,[17][18][19][20] but only a handful of studies have focused specifically on 'interstratified' illite/smectite clays [21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Pozzolanic reactivity of a calcined interstratified illite/smectite (70/30) clay

Garg

Skibsted

2016

Cement and Concrete Research

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Section: Introductionmentioning

confidence: 99%

Pozzolanic reactivity of a calcined interstratified illite/smectite (70/30) clay

Garg

Skibsted

2016

Cement and Concrete Research

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“…[11][12][13] One potential candidate for such secondary materials is "calcined clay", whose precursor material-clay minerals are widely abundant in the Earth's crust and also locally available in regions witnessing high population | 7721 GARG And SKIBSTEd and infrastructure growth. Whether calcined clays are to be used directly as a SCM for making sustainable concrete [14][15][16] or need to be alkali activated to form geopolymers, 17,18 an understanding of their dissolution kinetics is highly important. In the reaction of a silicate-rich SCM in an alkaline environment, such as in a hydrating portland cement blend, it has been long known that the dissolution of silicate species from the SCM particles is the initial rate-controlling step.…”

Section: Introductionmentioning

confidence: 99%

Dissolution kinetics of calcined kaolinite and montmorillonite in alkaline conditions: Evidence for reactive Al(V) sites

Garg

2019

J Am Ceram Soc

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Calcined clays are attracting significant research attention because of their potential to partially replace CO2‐intensive portland cement. This potential depends largely on their reactivity, especially dissolution under alkaline conditions. Identification and characterization of reactive sites in these amorphous calcined clays has so far not been reported. Here, we investigate kaolinite (1:1 clay) and montmorillonite (2:1 clay) calcined at different temperatures under alkaline conditions (0.1 mol/L NaOH). Solution compositions are determined in batch dissolution experiments, whereas 27Al and 29Si MAS and CP/MAS NMR are used to investigate the structure of the undissolved residues to identify sites that are reactive and undergo preferential dissolution. The highest Si and Al dissolution rates for kaolinite are observed for calcination at 700°C, corresponding to the temperature of optimum reactivity, whereas the rates decrease and become increasingly incongruent at higher temperatures. The Si and Al dissolution rates for optimally calcined kaolinite are 4 and 12 times larger than the corresponding rates for optimally calcined montmorillonite, in accord with the much higher reactivity of calcined kaolinite compared to calcined 2:1 clays. This superior performance of kaolinite is explained by novel 27Al NMR results, which show strong evidence for preferential dissolution of highly reactive pentahedral aluminum sites.

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“…Recent research on the use of naturally occurring clays with low to moderate kaolinite content has focused either on identifying the minimum required kaolinite content when the calcination conditions are optimised for the thermal activation of the kaolinite [11,12] (including use of these calcined clays in cement together with co-substituted limestone [12][13][14]), or on finding optimum calcination conditions with consideration not only of the kaolinite, but also of the 2:1 minerals contained in the clay, i.e. calcination temperatures substantially above 800°C [11,[15][16][17][18]. These latter studies confirmed that reactive pozzolans can be obtained from clays with illite and/or smectites, but that these minerals require higher calcination temperatures and yield lower strengths of blended cement pastes than kaolinitic clays.…”

Section: Introductionmentioning

confidence: 99%

Comparison of calcined illitic clays (brick clays) and low-grade kaolinitic clays as supplementary cementitious materials

et al. 2019

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The use of calcined clays as supplementary cementitious materials (SCMs) has been identified as a viable option to decrease the CO 2 emissions related to cement production. However, while extensive data is available about kaolinitic clays in this context, other clays such as illitic clays appear to be under-studied. Therefore, in the present study, two illitic clays were compared to two low-grade kaolinitic clays in terms of transformations in the calcination temperature range 650-900°C, and performance of the calcined clays in blended cement pastes as measured by strength evolution, heat release, hydrated phase formation and portlandite consumption. The illitic clays required a higher calcination temperature for complete dehydroxylation of their illite than what is necessary for dehydroxylation of kaolinite. These higher calcination temperatures also led to particle sintering, significantly decreasing the specific surface area of the illitic clays, particularly for the clay with the higher Fe 2 O 3 content. Nevertheless, while the kaolinitic clays generally exhibited the best performance as SCM, the illitic clay with lower Fe 2 O 3 content performed similar to the kaolinitic clays when calcined at optimum temperature and applied at a moderate substitution rate. These findings demonstrate that several different clays have the potential to be used as SCM and indicate possible routes to identify suitable deposits for this purpose.

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Calcined kaolinite–bentonite clay blends as supplementary cementitious materials

Cited by 138 publications

References 55 publications

Pozzolanic reactivity of a calcined interstratified illite/smectite (70/30) clay

Pozzolanic reactivity of a calcined interstratified illite/smectite (70/30) clay

Dissolution kinetics of calcined kaolinite and montmorillonite in alkaline conditions: Evidence for reactive Al(V) sites

Comparison of calcined illitic clays (brick clays) and low-grade kaolinitic clays as supplementary cementitious materials

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