Akademik Veri Yönetim Sistemi
CONSTRUCTION AND BUILDING MATERIALS, cilt.504, 2025 (SCI-Expanded, Scopus)
Harnessing red mud (RM) and fly ash (FA) on a large scale could transform these industrial byproducts into valuable resources, driving greener, low-carbon advancements in the aluminum industry. Mastering mechanical and carbon sequestration behaviors of RM-FA based geopolymer grouting materials will provide theoretical support for achieving this goal. The carbonation characteristics, including depth, area, and CO2 absorption rate, were evaluated for specimens with different precuring durations via phenolphthalein titration and gravimetric methods. The mechanical features of carbonation-cured materials were then tested. Through wide-ranging microstructural characterization systems (XRD, FTIR, SEM-EDS, TG-DTG, and LF NMR), evolution of phase composition, microstructure, and pore-fracture features during both carbonation and geo polymerization processes was systematically explored under varying precuring conditions. Results demonstrate that extending pre-curing duration significantly mitigates NaHCO3-induced obstruction of CO2 diffusion channels, increasing carbonation depth from 1.01 +/- 0.05 mm to 5.07 +/- 0.11 mm (RSD < 5.0 %). In specimens with shorter pre-curing periods, elevated free alkali content enhances CO2 absorption to 2.29 +/- 0.07 % (RSD < 5.0 %) (C1P). Notably, C14P specimens achieve maximum CO2 sequestration of 30.9 kg/ton through CaCO3 formation, benefiting from both unimpeded CO2 diffusion (absence of excessive NaHCO3 blockage) and sufficient Ca2 + availability. The 40.58 % strength deterioration in C1P specimens stems from the competition between early-stage geo polymerization and carbonation reactions. Subsequent standard curing promotes the growth of Na2CO3/CaCO2 crystals and further drives geo polymerization, thereby significantly reducing the final strength degradation rate of the specimens. Microstructural analysis confirms that carbonation-induced suppression of N(C)-A-S-H gel/ettringite formation increases total pore volume, constituting the primary reason for strength degradation. These findings systematically elucidate the interaction mechanisms between geo polymerization and carbonation reactions under varying pre-curing conditions, providing a theoretical basis for synergistically optimizing the CO2 sequestration capacity and mechanical performance of RM-FA based geopolymer materials.