Three levels of a laterite profile were used: loose laterite L1, crust L2, and allotrite L3. These materials were calcined at 600°C to obtain samples F1, F2, and F3, respectively and were acitvated using a sodium silicate solution. Three concentrations were developed: 8 M for the G1, G2, and G3 series, 10 M for the H1, H2, and H3 series, and 12 M for the K1, K2, and K3 series. The raw materials and products developed were characterized to understand the structural transformations and usage properties. The results obtained showed that the three levels of laterite consist of quartz, kaolinite, hematite, goethite, and illite. Calcination led to the disappearance of kaolinite in F1 and F2, while traces of kaolinite remain in F3. Evaluated at 28 days at room temperature, the three-point bending strength revealed that sample K2 performed better with a strength of 26.50 MPa, attributed to the highly released Si, Fe and Al oligomers allowing the formation of compact structure. However, the samples stabilized at 8 M and 10 M performed less than those activated at 12 M. This observation was also noted for thermal conductivity, K2 conducts more heat than the other materials, and G1 conducts less. Water absorption and porosity show that G1 is more absorbent and more porous, while K2 is less absorbent and less porous. The results show that increasing alkalinity improves the mechanical and physical performance of geopolymer composites. The armor appears to be the appropriate level for stabilization in an alkaline environment for lateritic soils. The produced geopolymer binders could be used in engineering applications where high strength is required. Finally, the present work promotes the use of laterite soil in geopolymer synthesis by identifying the type of laterite and the level corresponding to the required properties.
Abomo et al. (Sun,) studied this question.