Geopolymer has been developed as an alternative material to Portland cement. Geopolymer is based on the polymerization of alkaline activation and oxide of silicon and aluminium. These oxides can be found in many pozzolanic materials such as metakaolin and the wastes from industries and agricultures in Thailand, e.g., fly ash, bagasse ash and rice husk ash. Pozzolanic materials were selected as source materials for making geopolymers into 4 different types. Sodium hydroxide concentration of 10 Molar (10MNaOH) and sodium silicate (Na2SiO3) solutions were used as alkaline activators by the mass ratio of Na2SiO3/NaOH at 1.5. The mixtures were cast in 25×25×25 mm. cubes. After casting, the geopolymers were cured at 80๐C for 24 hrs. in an oven and then at room temperature for 7 days. The pozzolanic materials effects, the Si/Al molar ratio and the Na/Al molar ratio were studied and characterized. An X-ray fluorescence (XRF) was chosen to determine the percentages of silica and alumina in order to verify the proper ratio of the fly ash, Rice husk ash, Bagasse ash and Metakaolin.The study also included the impact on mechanical and physical properties such as compressive strength, water absorption, density and porosity.
Sago pulp and rice husk as an alternative material for the cultivation of oyster mushroom (Pleurotus ostreatus)