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Electric arc furnace slag (EAF-S), coming from a steel productive plant in Italy, has been used as new source for geopolymers synthesis. The slag has been geopolymerized alone and with different content of metakaolin (MK) with the aim to investigate if EAF-S content plays a role in geopolymerization process. Mechanical properties results and microstructure analysis highlight that the optimum weight ratio MK/EAF-S to be used as starting materials is 40/60, 30/70, 20/80. Moreover EAF-S, when used with MK, directly participates in the formation of calcium-rich alumino-silicate gels.

Foaming methods to reduce the density of geopolymers were investigated as low density geopolymers are increasingly being reported in the literature to be effective in improving the insulating properties. However, there is no consistency in foaming methods and as such this study was performed to compare different foaming agents in order to better understand their effect on the properties of geopolymers. In particular, a surfactant and hydrogen peroxide were used individually and in combination to ensure a homogeneous pore distribution in the slurry. Physical and microstructural properties of the hardened low density geopolymers are presented and discussed. The behaviour under fire conditions of fibre reinforced and foamed geopolymer samples will also be presented in order to appreciate the suitability of geopolymer composite in high temperature applications.

The growing focus on issues related to the control of CO2 emissions, energy conservation and waste recycling pushes the construction industry to tackle the challenge of sustainable development. The production of ordinary Portland cement (OPC), main product of the sector, is one of the most polluting in terms of CO2 emissions, thus finding alternative binder is becoming an urgent matter. Geopolymers are largely investigated for this purpose, but studies concerning the durability of reinforced conglomerates prepared with alkali activated binders are only few. The present work aims at investigating the durability performances of steel reinforced geopolymer mortar samples based on carbon fly ash in comparison with OPC mortar. The effect of different Na2O/SiO2 molar ratios in the geopolymer mixes is evaluated in terms of mechanical and microstructural properties as well as corrosion resistance in a chloride rich environment. The obtained results show that under the same severe environmental conditions more limited chloride amounts penetrate in reinforced fly-ash geopolymers where a better corrosion behaviour is also detected up to a week of exposure for samples with a nominal Na2O/SiO2 molar ratio equal to 0.12 and 0.14. Instead, the corrosion resistance is quite similar to that of reinforced OPC mortar when a period of three months is considered.

Geopolymers, and more in general alkali activated materials (AAM), are a new class of materials obtained by alumino-silicates precursors activated by means of alkaline solutions. Indeed, the term geopolymers is usually strictly referred to pure alumino-silicates such as metakaolin as starting material, whereas when the precursors also contain calcium oxide the resulting products are usually defined AAM. Geopolymerization technology can be more easily considered a sustainable process when industrial waste is used as precursors and the consolidation process occurs at room temperature. With these premises, alkali activation may be a very promising technology for the ceramic sector as well as construction industry. In this work, waste coming from bricks production has been used to obtain, at room temperature, geopolymers with different porosity tuning the sodium silicate content in the feed. Microstructure analysis carried out by means of mercury intrusion porosimeter and scanning electron microscopy is reported and discussed.

Electric arc furnace slag (EAF-S), coming from a steel productive plant in Italy, has been used as new source for geopolymers synthesis. The slag has been geopolymerized alone and with different content of metakaolin (MK) with the aim to investigate if EAF-S content plays a role in geopolymerization process. Mechanical properties results and microstructure analysis highlight that the optimum weight ratio MK/EAF-S to be used as starting materials is 40/60, 30/70, 20/80. Moreover EAF-S, when used with MK, directly participates in the formation of calcium-rich alumino-silicate gels.