Effect of the Alkali Metal Activator on the Properties of Fly Ash-Based Geopolymers

• Published in: Industrial & engineering chemistry research 1999-10, Vol.38 (10), p.3932-3941
• Main Authors: van Jaarsveld, J. G. S, van Deventer, J. S. J
• Format: Article
• Language: English
• Subjects: 01 COAL, LIGNITE, AND PEAT; Applied sciences; CHEMICAL ACTIVATION; CHEMICAL PROPERTIES; COMPRESSION STRENGTH; Exact sciences and technology; FLY ASH; Inorganic and organomineral polymers; LINERS; MATERIALS SCIENCE; MATERIALS TESTING; Other industrial wastes. Sewage sludge; PHYSICAL PROPERTIES; Physicochemistry of polymers; Pollution; POLYMERS; Preparation; SANITARY LANDFILLS; WASTE PRODUCT UTILIZATION; Wastes
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/ie980804b

The alkali and alkali earth metal cations present during the formation of most known aluminosilicate structures have a very significant effect on both the physical and chemical properties of the final product. Geopolymers are no exception, although this effect has not been thoroughly quantified and in the case of waste-based geopolymers it has not received any significant attention. The present study investigates the effect of mainly Na+ and K+ on the physical and chemical properties of fly ash-based geopolymeric binders both before and after setting has occurred. A variety of tests were conducted, including rheological measurements, various leaching tests, compressive strength testing, specific surface area determinations, and infrared spectroscopy (IR). It is concluded that the alkali metal cation controls and affects almost all stages of geopolymerization, from the ordering of ions and soluble species during the dissolution process to playing a structure-directing role during gel hardening and eventual crystal formation.