Mineralogical effect on the pozzolanic reactivity of a Mexican lacustrine soil

Clay minerals have been used as natural pozzolans with the aim of reducing CO2 emissions, and densifying the matrix with hydration products in pastes and mortars. This study assesses the pozzolanic reactivity of a natural lacustrine material in its natural and thermally-treated states. The influence of mineralogical characteristics on the physicochemical and mechanical properties of pastes and mortars with a level of replacement of 20% was evaluated. Studies of crystallography, chemical analysis, morphology, mineralogical phases, particle size distribution and enthalpy were conducted. The results indicate that thermally-activated systems have better structure and develop a more homogeneous matrix. It was observed that poorly-crystalline mineralogical impurities do not influence the pozzolanic reactivity; moreover, the PAI (pozzolanic reactivity index) was in the order 86.59% in mortar systems including thermally-treated material, which is a much higher value when compared to only 41.92% obtained when the material was in its natural state.