Pozzolanic Reactivity of Low Grade Kaolinitic Clays: Influence of Mineralogical Composition
The influence of chemical and mineralogical composition of five Cuban clays in the pozzolanic reactivity of its calcination products is studied in this research. Raw materials were chemically and mineralogically characterized by XRF, XRD and TGA. Pozzolanic reactivity of 800 °C calcination products was evaluated by heat released in chemically modified lime-pozzolan pastes, and by compressive strength in mortars with a 30 % substitution of OPC by calcined clays. Preliminary results shown that pozzolanic reactivity of clays calcined at temperatures that guarantees a complete dehydroxylation of the raw materials could be qualitatively assessed by its relative positions along the diagonal trend in an Al2O3–SiO2–OH− ternary plot, where pozzolanic reactivity is related to the percent of structural hydroxyl groups and the percent of Al2O3 in the raw material. Conducted pozzolanic reactivity test highlight the potential of kaolinite rich red clay soils as source for the obtaining of highly reactive pozzolanic materials.
KeywordsCompressive Strength Clay Mineral Mineralogical Composition Pozzolanic Reactivity Clay Sample
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The authors would like to thanks the valuable collaboration of Francois Avet on the performance of lime-pozzolan reactivity tests, and the Laboratoires des Matériaux de Construction (LMC) of the École Polytechnique Fédérale de Lausanne (EPFL) for offering their facilities. The authors would also like to acknowledge to the Cuban Geological Services, for the technical support in clay deposits sampling.
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