The characterisation of source materials in fly ash-based geopolymers

In recent years geopolymers have emerged as novel materials having unique and highly desirable chemical and mechanical properties. The technology of geopolymerisation is gaining commercial interest because it has been demonstrated that, in certain cases, the properties of geopolymeric materials are superior to existing cementitious systems. Source materials used during the synthesis of geopolymers from industrial by-products such as fly ash have an important role in determining the final properties of the geopolymer matrix. It is proposed in the current work that this is caused by the fact that not all of the waste material is dissolved and, therefore, some of the original structures of waste particles remain intact, becoming part of the new geopolymer structure and serving to either weaken or strengthen the newly formed structure. The current work uses XRD and FTIR techniques to characterise fly ash obtained from different sources in order to gain a greater understanding of the effect of phase composition on the dissolution behaviour, reactivity, and final physical and mechanical properties of fly ash-based geopolymeric materials.