Enhancing reactivity in muscovitic clays: Mechanical activation as a sustainable alternative to thermal activation for cement production

Abstract

The use of calcined clays in the construction industry is thriving. However, muscovitic or illitic clays, which constitute a large portion of the available clay resources, are hardly activated by thermal processes. This work aims to enhance the reactivity of raw muscovitic clay through mechanical activation. Various combinations of milling time and rotation speed were evaluated. The results confirmed that a highly amorphous material was obtained through mechanical activation, while thermal activation led to muscovite dehydroxylation without inducing amorphisation, resulting in the formation of crystalline dehydroxylated muscovite. The reactivity of the activated clays as a potential precursor for cement production was assessed through pozzolanic activity measurements and Si and Al potential availability. Both confirmed that mechanically activated muscovitic clay presented significantly higher reactivity than calcined muscovitic clay, obtaining an excellent pozzolanic material or an alternative cement precursor. Accordingly, mechanical activation of muscovitic clays could effectively introduce these types of clay in the cement industry.