Identificación y evaluación de arcillas caoliníticas para la producción de cemento ternario LC³ y adiciones minerales activas LC²

Introduction: The industrial scale implementation of the production of LC3 cements and the corresponding active mineral addition (LC2) is limited because there is no adequate strategy that allows for the identification and evaluation of the existing clay deposits as a source of supplementary cementitious materials (MCS) and its scarce reported resources. The goal of this work is to develop a procedure that allows for the identification and evaluation of clay deposits to be used as MCS and to establish the parameters for their suitable selection. Methods: Four clay deposits were studied, which were chemically and mineralogically characterized. The clays investigated were calcined at 750 and 850 ºC and were characterized from the chemical point of view and the specific surface, and their pozzolanic reactivity was assessed. The calcined clays were used in the formulation of LC3 cements, which were evaluated in their anhydrous state, in pastes and in mortars. Results: In the characterized clays there is a predominance of clay minerals from the kaolinite group, while their relatively high iron content limits their exploitation in applications of industrial kaolins. The calcined products show an excellent pozzolanic reactivity and the binders show a similar behavior to the P-35 cements. Conclusions: The four deposits present potentialities for the production of MCS on an industrial scale. Kaolinite content is the factor with the greatest influence on pozzolanic reactivity. The presence of thermally unstable accompanying minerals during the calcination process also affects pozzolanic reactivity. The procedure developed constitutes a solid tool for evaluating the potentialities of clay deposits as a source of MCS.