| Abstract
| - X-ray absorption fine structure (XAFS) spectroscopy anddiffuse reflectance spectroscopy (DRS) were applied to assessthe solubility-limiting phase of Ni in cement systems.The study provides first direct spectroscopic evidence forthe formation of Ni- and Al-containing hydrotalcite-likelayered double hydroxides (Ni−Al LDHs) when cementmaterial (a complex mixture of mainly CaO, SiO2, Al2O3, Fe2O3,MgO, and SO3) was treated with Ni in artificial cementpore water under highly alkaline conditions (pH = 13.3). Thestudy shows that Ni−Al LDHs were formed in cementsuspensions oversaturated with respect to β-Ni(OH)2 andaged at room temperature for 150 days. This findingindicates that Ni−Al LDHs and not Ni-hydroxides maydetermine the solubility of Ni in cement materials.
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