Comparison of the Properties of Geopolymers from Using Fly Ash from Two Sources

The objective of this research was to develop geopolymer mortar using fly ash obtained from two different sources: fly ash from the power plant located in the Map Ta Phut Industrial Estate, Rayong Province, and fly ash from the Mae Moh power plant, Lampang Province. The study aimed to investigate the effects of varying proportions of Portland cement and fly ash on the compressive strength and setting characteristics of geopolymer mortar produced from both sources of fly ash. The experimental process involved mixing fly ash, Portland cement, sand, sodium silicate, and 14-molar sodium hydroxide solution. The prepared geopolymer mortar specimens were cured at ambient room temperature for periods of 7, 14, and 28 days. The test results demonstrated that fly ash from both sources could be utilized effectively as precursor materials for geopolymer mortar production. The fly ash from the Mae Moh power plant, classified as Class C, contains a high content of calcium oxide (CaO), which results in high early-age compressive strength. In contrast, the fly ash from the Map Ta Phut Industrial Estate, classified as Class F, contains higher levels of silica (SiO₂) and alumina (Al₂O₃), leading to enhanced long-term strength development. In conclusion, both types of fly ash exhibit suitable characteristics for use in the production of geopolymer mortar and show strong potential as alternative materials to conventional Portland cement in construction. Their rapid initial setting and high early compressive strength make them particularly suitable for structural repair applications.