SYNTHESIS AND CHARACTERIZATION OF INORGANIC POLYMERS (GEOPOLYMERS) PRODUCED FROM METAKAOLIN USING SODIUM SILICATE AND MILLET HUSK ASH AS ACTIVATORS

Abstract

The use of inorganic polymers (geopolymers) as cement has been encouraged because of its several advantages over Portland cement. This is due to the huge carbon dioxide (CO₂) emission that is involved which has great effects on climatic conditions. This work synthesized one-part inorganic polymers (geopolymers) using metakaolin, sodium hydroxide (NaOH), sodium silicate (Na₂SiO₃), and millet husk ash (MHA). The geopolymers were synthesized by adding water to the calcined kaolin, (NaOH) and (Na₂SiO₃). The resulting paste was cast for the compressive and flexural strength test. The casted samples were cured immediately at 60 ⁰C for 20 hours and de-molded. They were tested for mechanical properties after 1 and 7 weeks at room temperature. The above procedure was repeated by complete replacement of Na₂SiO₃ with MHA. The 7-weeks cured geopolymers were characterized by FTIR, XRD, SEM, and TGA to confirm the formation of synthesized geopolymers. The samples were also analyzed to study physicochemical properties. It was observed that the highest compressive and flexural strength was obtained at (17.06 N/mm² and 2.31 N/mm²) and (13.50 N/mm² and 1.14 N/mm²) for both Na²SiO³ and MHA geopolymers respectively. Therefore, the current study signified that the synthesized geopolymers can serve as a substitute for the cement with less effect on the climatic conditions.