Marl-based geopolymers incorporated with limestone: A feasibility study

The expanding raw materials base is one of the drivers for the further development of inorganic binders, including alkali-activated cements. This research focuses on studying marl with a high calcite/aluminosilicates ratio as a geopolymer precursor, and limestone as a mineral addition to this geopolymer. The calcination of marl at 800 °C resulting in the formation of reactive Si, Al, and Ca due to the dehydroxylation of clay minerals and decarbonation of calcite makes marl suitable for use as a geopolymer precursor. Calcined marl activated with sodium silicate and cured at ambient temperature had a 28-day compressive strength of 34 MPa. When incorporated with 50% limestone, the compressive strength became 39.2 MPa. XRD, TG/DSC, FTIR, optical and SEM have been used to investigate the reaction products, as well as the microstructure of the geopolymer hardened pastes.