Physical and mechanical characterization of calcined clays for use as supplementary cementitious material

Cement is the second most used material in the world. However, its production causes serious environmental impacts. The carbon dioxide emission of this type of industry has a significant contribution to global warming. The sustainability that civil construction promotes must not only be analysed after the construction of buildings, but in the entire construction stage, from the material to be used to the losses in the process. In this context, it is important to note that several alternatives have already been studied, such as the use of supplementary cementitious materials in concrete, such as rice husk ash, sugarcane bagasse and calcined clays. Although calcined clays are already used as a partial replacement for clinker in composite cements, several authors suggest that the material is capable of being used as a partial replacement for Portland cement. Thus, the objective of this work was to evaluate the potential application of calcined clays submitted to calcination thermal treatments for use as supplementary cementitious material. To achieve this objective, the clays were characterized and subsequently subjected to calcination in a muffle at temperatures equal to 500, 600, 700 and 800 °C, carrying out tests regarding the pozzolanic activity potential, performance as metakaolin and electrical conductivity. It was observed that for the proposed temperatures, the performance indices with Portland cement and use as metakaolin were met, demonstrating a high potential for use. Upon verifying the data found, the sample calcined at 800 °C showed the best results, both in mechanical performance (performance index with Portland cement and performance as metakaolin) and in the electrical conductivity test. In this sense, it appears that the use of calcined clays has the possibility of application as a material to minimize the adverse effects caused by the manufacture of Portland cement. © 2023, The Author(s), under exclusive licence to Springer Nature Switzerland AG.