Effect of chemical admixtures on properties of high-calcium fly ash geopolymer

• Published in: International journal of minerals, metallurgy and materials Vol. 18; no. 3; pp. 364 - 369
• Main Authors: Rattanasak, Ubolluk, Pankhet, Kanokwan, Chindaprasirt, Prinya
• Format: Journal Article
• Language: English
• Published: Beijing University of Science and Technology Beijing 01.06.2011; Springer Nature B.V; Department of Chemistry and Conter for Innovation in Chemistry, Faculty of Science, Burapha University, Chonburi 20131, Thailand%Sustainable Infrastructure Research and Development Center, Department of Civil Engineering, Faculty of Engineering, Khon Kaen University, Khon Kaen 40002,Thailand
• Subjects: Admixtures; Calcium chloride; Calcium sulfate; Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Composites; Compressive strength; Corrosion and Coatings; Fly ash; Geopolymers; Glass; Materials Science; Metallic Materials; Metallurgy; Natural Materials; Pastes; Sodium silicates; Sodium sulfate; Sucrose; Sulfates; Surfaces and Interfaces; Thin Films; Tribology; Workability; 凝结时间; 化学外加剂; 地聚合物; 地质聚合物; 性质; 抗压强度; 终凝时间; 高钙粉煤灰; chemical admixtures; fly ash; setting time; geopolymers
• ISSN: 1674-4799; 1869-103X
• DOI: 10.1007/s12613-011-0448-3

Owing to the high viscosity of sodium silicate solution, fly ash geopolymer has the problems of low workability and rapid setting time. Therefore, the effect of chemical admixtures on the properties of fly ash geopolymer was studied to overcome the rapid set of the geo-polymer in this paper. High-calcium fly ash and alkaline solution were used as starting materials to synthesize the geopolymer. Calcium chloride, calcium sulfate, sodium sulfate, and sucrose at dosages of 1wt% and 2wt% of fly ash were selected as admixtures based on concrete knowledge to improve the properties of the geopolymer. The setting time, compressive strength, and degree of reaction were recorded, and the microstructure was examined. The results show that calcium chloride significantly shortens both the initial and final setting times of the geopolymer paste. In addition, sucrose also delays the final setting time significantly. The degrees of reaction of fly ash in the geopolymer paste with the admixtures are all higher than those of the control paste. This contributes to the obvious increases in compressive strength.