Sicilian clay sediments as precursor for alkali activated materials

Abstract

In this work, we focused on the possibility of using clay sediments found in Sicily as precursors to produce alkali activated materials (AAMs) with properties comparable to those of traditional materials used in construction. Two different clays were selected: Plio-Pleistocenic marly clay (PP) and Numidian Flysh clay (NU) to test the use of sediments with and without calcite. AAMs were prepared using precursors thermally treated at 700 °C and alkaline activator solutions as NaOH 4, 6 and 8 M with or without sodium silicate. All samples were cured at 85 °C for 20 h and at room temperature for 28d. Mineralogical analyses, FTIR data, SEM/EDS morphological and chemical observations showed the formation of a polycondensed gel after 20 h. AAMs obtained from calcite-rich clayey sediments (thermally treated) achieved good compressive strength after 28 days with all activators. However, AAMs based on thermally treated calcite-free clays only showed good compressive strength development only when activated with 8 M NaOH and sodium silicate.