The potential use of geopolymeric materials to immobilise toxic metals: Part II. Material and leaching characteristics

The stabilisation and solidification of waste materials by the technology of geopolymerisation is fairly unknown and has not been studied in any depth. This paper presents some experimental evidence as to the physical and chemical characteristics of geopolymers manufactured from fly ash originating from two different regions. It has become apparent that these materials could be used for a wide variety of environmental and other applications such as the immobilisation of heavy metals and the fabrication of structural products. In this study compressive strength testing, specific surface area determinations, Transmission Electron Microscopy (TEM), Nuclear Magnetic Resonance (NMR) and leaching tests were used in characterising a number of geopolymer matrices. It is also shown how the inclusion of heavy metal ions, alkali metal cations and different processing conditions affect the physical and chemical characteristics of the final product.