**2.2 Synthesis of different forms of geopolymers**

The synthesis of geopolymers is carried out by mixing source materials containing aluminosilicate (sand dune), fly ash with a high calcium (Ca) classified as (F), and an alkaline solution (NaOH 13 M). The source materials used are FAES washed with acidic solution (HCl 1 M) to eliminate impurities and minimize the rate of calcium and limine as producers of carbon dioxide (CO2), calcined at 700 to 900°C, and sand dune (Algerian sand) leached with acid solution (HCl 1 M) and mixed with alkaline solution (NaOH 13 M) to prepare sodium silicate (Na2SiO3). In the last step, four samples of geopolymers were prepared for comparison, as shown in **Table 3**. The final product was placed in molds at room temperature for 24 hours and then stored in an oven at 80°C for another 24 hours. **Table 4** presents the results of the XRF assay analysis. The sample is full of silica and limine, which is a suitable raw material to begin the geopolymerization process.
