CO2 Curing of Ca-Rich Fly Ashes to Produce Cement-Free Building Materials

In this study, fly ash (FA) compacts were prepared by accelerated carbonation as a potential sustainable building material application with the locally available ashes (oil shale (OSA), wood (WA) and land filled oil (LFA)) of Estonia. The behaviour FAs performance 100% FA based evaluated on obtained values CO2 uptake compressive strength. influence different variables (compaction pressure, curing temperature, concentration, pressure) strength development investigated reaction kinetics process tested reaction-order models. A reasonable relation was noted between compacts. porous surface structure hydrated OSA WA changed after due to calcite formations (being primary product), especially portlandite crystals. increase gas concentration improved levels However, positive effect increasing compaction pressure more apparent final 10 36 MPa 11 13 wt%, respectively, under various operation conditions. Moreover, mixed design (OSA/LFA WA/LFA) resulted in low-strength density compared single compacts, yet higher achieved (approximately 15% mass) design. conformity Jander equation (3D-diffusion-limited model) other order models for representation mechanism WA. activation energy compact calculated 3.55 kJ/mol 17.06 kJ/mol.