Formulation d'un liant écologique à base d'argile Kaolinitique riche en gibbsite

The addition of 10 wt% aluminum hydroxide to two crude kaolinitic clays, a commercial and a natural freshly mined one, has enhanced their pozzolanic activity, more substantially in the natural sample containing gibbsite. The obtained blends were used as replacement of 20 wt% of Portland cement in the formulations of pastes and mortars which exhibited significant decrease of setting time and increase of compressive strength from early age to 28 days. Also, SEM/EDX analyses showed very heterogeneous structures with hydrated phases identified from XRD. Specific interpretation of the role played by aluminum hydroxide revealed its aptitude to promote the formation of metastable hydrated phases (CAH 10 /C 2 AH 8 ) at early age, which temporally inhibited the hydration of cement. This progressive transformation led to the formation of more stable hydrated phases such as C–A–S–H which favored the increase of mechanical strength of the specimens. The sequence of transformation reactions is fully obtained with limited aluminum hydroxide content in clays. Either added as synthetic or naturally occurring in clays, aluminum hydroxide has close role in the strengthening process of cement. Hence, kaolinitic clays that naturally contain gibbsite are suggested as suitable supplementary cementitious material for partial replacement of cement.

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Pozzolanic activity of kaolins containing aluminum hydroxide

Leussa

Libessart

Djelal

et al. 2020

Sci Rep

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Physicochemical Characterisation for Potential Uses as Industrial Mineral of Bauxite from Débélé, Guinea

Balde¹,

Djangang²,

Diallo³

et al. 2021

MSCE

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Assessing the potential uses as industrial mineral, bauxite from Débélé, Guinea, has been characterised by chemical and mineralogical analyses, the determination of the amorphous content, the rate of portlandite consumption in an aqueous solution, the strength activity index, and the thermal behaviour up to 1200˚C. It was evidenced that the raw sample is gibbsite-rich type bauxite with about 45.06 wt% of alumina, 23.80 wt% of iron oxide, and 1.74 wt% of silica. It meets the chemical composition required for bauxites used for refractory cement. During heating, the raw bauxite undergoes high densification with low linear shrinkage, motivating a potential use in dense ceramic compositions with high thermal stability. Also, the heating at only 600˚C gives a significant pozzolanic activity in combination with Portland cement. The correlation between the pozzolanicity, the amorphous phase content, and the specific surface area indicated that the raw and the calcined materials present an interesting reactivity for using them in alternative cement formulations.

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Formulation d'un liant écologique à base d'argile Kaolinitique riche en gibbsite

Cited by 2 publications

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Pozzolanic activity of kaolins containing aluminum hydroxide

Pozzolanic activity of kaolins containing aluminum hydroxide

Physicochemical Characterisation for Potential Uses as Industrial Mineral of Bauxite from Débélé, Guinea

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Formulation d'un liant écologique à base d'argile Kaolinitique riche en gibbsite

Cited by 2 publications

References 0 publications

Pozzolanic activity of kaolins containing aluminum hydroxide

Pozzolanic activity of kaolins containing aluminum hydroxide

Physicochemical Characterisation for Potential Uses as Industrial Mineral of Bauxite from D&#233;b&#233;l&#233;, Guinea

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Physicochemical Characterisation for Potential Uses as Industrial Mineral of Bauxite from Débélé, Guinea