Design and characterization of iron–calcium–aluminium–silicate–hydrate as low-temperature binder

This work aims to synthesize new cementitious materials (binders) using marble powder, rice husk ash, activated laterite and NaOH solution by applying low energy process. The binder was used to stabilize solid precursors (laterite and pozzolan). To achieve this objective, calcium–silicate–hydrate (CSH) was first synthesized at different temperatures (26, 50, 80 and 100 °C). The best physical–mechanical properties were chosen to produce iron–calcium–aluminium–silicate–hydrate [Fe–C(A)SH] at different concentrations of sodium hydroxide solution: 4, 5, 6 M. Finally, the formulated binder at 6 M of NaOH solution was used to stabilize laterite and pozzolans at the following proportions 20%, 30%, 40% and 50%. The samples were characterized after 28 days of curing at room temperature. FT-infrared spectroscopy, X-ray diffraction, and environmental scanning electron microscope ESEM-EDS permitted to confirm the formation of CSH, and Fe–C(A)SH. The mechanical test used to evaluate the performance showed that the incorporation of 10% iron-rich laterite into CSH increased the strength up to 42.93 MPa and the addition of Fe–C(A)SH in the laterite/pozzolans increased the compressive strength of the final product (15.34 and 15.8 MPa for laterite and pozzolan, respectively). The highest concentration (6 M) increases the alkalinity and reduces the efficiency of silicate polymerization affecting the final structural compound. From the results, low-energy Fe–C(A)SH-based cement and stabilized compounds appeared promising for the development of sustainable infrastructures.