Abstract As one of the main hydration products, Ca(OH)2 has important effects on mechanical properties and durability of hardened cementitious materials. In this study, Ca(OH)2 precipitates were synthesized by continuous feeding of CaCl2 and NaOH solutions into a bulk solution containing triethanolamine (TEA) or diethanolamine (DEA). Analytical techniques including electric conductivity measurement, TOC, ICP − OES, XRD, FTIR and SEM were employed to investigate the impacts of the alkanolamines on the precipitation process and morphology of the synthetic Ca(OH)2. Results show that TEA strongly hinders the nucleation and growth of Ca(OH)2 precipitate due to the complexation effect with Ca2+ ions in solution. The chemical incorporation of TEA into the lattice structure greatly disrupts lattice structure of the obtained Ca(OH)2 precipitates and alters the morphology from typical hexagonal prism of pure portlandite to vertically stacked or randomly agglomerated Ca(OH)2 lamellae crystals with much smaller size. In contrast, DEA exhibits little effect on the precipitation process and morphology of portlandite.

中文翻译：

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两种烷醇胺对氢氧化钙结晶和形貌的影响

摘要 Ca(OH)2作为主要的水化产物之一，对硬化胶凝材料的力学性能和耐久性有重要影响。在本研究中，通过将 CaCl2 和 NaOH 溶液连续加入含有三乙醇胺 (TEA) 或二乙醇胺 (DEA) 的本体溶液中，合成了 Ca(OH)2 沉淀物。采用包括电导率测量、TOC、ICP-OES、XRD、FTIR 和 SEM 在内的分析技术来研究烷醇胺对合成 Ca(OH)2 的沉淀过程和形态的影响。结果表明，由于与溶液中的 Ca2+ 离子的络合效应，TEA 强烈阻碍了 Ca(OH)2 沉淀物的成核和生长。TEA 在晶格结构中的化学结合极大地破坏了所获得的 Ca(OH)2 沉淀物的晶格结构，并将形态从纯硅酸盐的典型六棱柱转变为具有更小尺寸的垂直堆叠或随机聚集的 Ca(OH)2 片晶. 相比之下，DEA 对硅酸盐的沉淀过程和形貌影响不大。