Geopolymerization as Effective Measure for Reducing Risks during Coal Ashes Handling, Storage and Disposal

Abstract

In this paper a research on the synthesis of geopolymers based on coal ashes, with consequent reduction to a consolidated form, was reported with the aim of proposing a procedure to transform potentially dangerous wastes into safe and possibly useful secondary materials (e.g. bricks and boards). Ash from pulverized coal (PC) combustion plant was used in tests of geopolymerization, performed with different ash/alkali compositions. The produced samples were characterized with particular focus on stability in water and leaching behaviour in comparison with raw ashes. The results of the research prove that coal ash can be converted into geopolymers in a rather simple way. The leaching of elements is not dramatically affected by the basic attack, but some controversial findings need further investigation. In general, the geopolymerization increases the safety of ash handling and disposal, thank to higher particle size and lower exposed surface.