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.