Thermal stability and microstructural analysis of inorganic polymer binders based on Italian and Australian fly ash

A comparative study between Italian and Australian fly ash and their use as precursors for inorganic polymer binders is carried out with the aim to find an alternative to the current valorisation of Italian fly ash as supplementary cementitious material. As the coal origin and combustion temperature directly influence fly ash nature and composition, the final products of the two precursors obtained by alkali activation at room temperature behave differently both at the fresh and hardened state. Single mode pore size distributions and largely distributed pore dimensions have been determined for Australian and Italian fly ash based samples. Thermal properties are also influenced by the different phases formed during the activation process, thus confirming that the chemical composition of the precursor is a key element to understanding this new class of materials.