Thermo-physical characterization of a metakaolin-based geopolymer incorporating calcium carbonate: A case study

A geopolymeric material (referred as G0) was synthesized by reacting a silicate alkaline solution (mixture of sodium and potassium hydroxides with sodium silicate) with metakaolin. Various formulations (GC1 to GC12) have been synthesized by partially replacing kaolin with different contents of calcium carbonate. The thermal conductivity was evaluated from the density, specific heat capacity at constant pressure and thermal diffusivity (by flash method). The results revealed that these geopolymer formulations exhibit a good thermal stability at low temperature. In addition, the thermal conductivity increases when the test temperature is increased. Addition of calcite up to 12 wt% did not alter the thermal conductivity. The designed materials exhibit good combination of mechanical properties as well. In addition, the thermal performance of the developed material incorporated in an external wall and exposed to the real climatic conditions, was investigated. It was found that the wall made with developed geopolymer ensures a good reduction of surface temperature and heat flux as well as the heating and cooling demand compared to a wall without geopolymer. •A metakaolin-based geopolymer was elaborated.•Calcium carbonate was incorporated by partial replacement of the metakaolin.•Thermophysical properties of geopolymers were investigated.•Obtained geopolymers present a good thermal stability at temperatures below 88 °C.•Addition of calcite to the geopolymer (up to 12 wt%) did not alter the thermal conductivity.