Mechanical and thermal properties of fly ash-filled geopolymers

Fly ash recycling reduces the amount of waste to be treated or disposed in landfills, allowing both to decrease the environmental damage and to save the costs of transport and disposal of waste. Systems with different percentages in mass of fly ash (20, 50 and 70 mass%) and the remaining part of pure metakaolin were synthesized. The effect of fly ash on the mechanical and thermal properties of a new geopolymer has been investigated in this paper. Fourier transform infrared spectroscopy has allowed us to verify the bonds formation between the geopolymeric matrix and the fly ash. The consolidation of the materials has been confirmed by pH and conductivity at up to 28 days of hardening. Dynamic mechanical analysis, differential scanning calorimetry and thermogravimetric analysis were performed in order to evaluate the thermo-mechanical performance of this new geopolymer in comparison with its counterpart pure geopolymer.