Compatibility studies of N-A-S-H and C-A-S-H Gels in Alkali-Activated Geopolymer Mortar

The primary reaction products in the alkali-activated green tuff alumino-silicate geopolymer mortar are Natrium (sodium) Aluminum-Silicate Hydrate (N-A-S-H) and Calcium Aluminum-Silicate Hydrate (C-A-S-H) gels. The alkaline activation was achieved using NaOH with a molarity of ۴ mol/dm۳ and sodium silicate with a ratio of ۲.۳–۲.۴. Alkaline activators represent a possible solution for a sustainable environment and reducing CO۲ emissions. The presence of sodium hydroxide with higher alkalinity indicates the decomposition of sodium at an older age, as seen in SEM-EDS, XRD, XRF, and FT-IR analyses, and eventually cracking. The main phase present in the alkali-activated green tuff mortar with the optimal sodium hydroxide with a molarity of ۴ mol/dm۳ are calcium silicate hydroxide hydrate (Ca۴.۵Si۶O۱۵ (OH)۳ ۲H۲O), sodium calcium aluminum silicate hydrate (Na۳Ca۳.۳۶Al۹.۶۸Si۲۶.۵۶O۷۲ (H۲O)۲۴.۴۸), zeolite (Si۸Al۴Ca۲O۲۴ (H۲O)۱۲), sodium silicate hydrate (Na۴.۱۲Si۳۶O۷۲ (H۲O)۲۳.۱۲) and sodium aluminum silicate hydrate (Na۴.۱۲Si۳۶O۷۲ (H۲O)۲۳.۱۲). At the initial stages, calcium in slag from the forging furnace stabilizes (N, C)-A-S-H gels, causing C-A-S-H gels to predominate over N-A-S-H. Over time, the trend reverses, with N-A-S-H becoming dominant. Ternary compositional diagrams show the range of chemical elements and the assemblage of resulting phases (minerals) at ۱۸۰ days of age.

کلیدواژه ها:

Green Tuff ، Alkali-Activated Mortars (AAMs) ، Mortar ، Geopolymer ، N-A-S-H