Magnesium potassium phosphate (MKP) cement-based materials could be suitable for concrete repairs in marine environments. In this study, the effect of seawater on the hydration of MKP cements at different magnesium-to-phosphate molar ratios was investigated using mainly diluted suspensions. Compared to deionized water, seawater can slow down MKP cement hydration, which is attributed to the combined effect of Na, K, Mgand Ca ions. The Cl and SO in seawater can reduce the pH in MKP cements. The amount of seawater influences the hydrate assemblages, resulting in mainly K-struvite at low liquid-to-solid (l/s) ratio of 0.25, to hazenite at l/s ratio of 5 and to bobierrite at high l/s ratio of 50, consistent with the thermodynamic calculations. The modelling and experiments showed the destabilization of K-struvite to hazenite by Na and the formation of bobierrite and possibly amorphous hydroxyapatite by Mg and Ca.

中文翻译：

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海水对磷酸镁钾水泥水化的影响


磷酸镁钾（MKP）水泥基材料可适用于海洋环境中的混凝土修复。在本研究中，主要使用稀释悬浮液研究了海水对不同镁磷摩尔比的 MKP 水泥水化的影响。与去离子水相比，海水可以减缓MKP水泥的水化，这归因于Na、K、Mg和Ca离子的共同作用。海水中的 Cl 和 SO 会降低 MKP 水泥的 pH 值。海水量影响水合物组合，液固比 (l/s) 为 0.25 时主要为钾鸟粪石，l/s 比为 5 时主要为铁锂矿，l/s 比为 5 时主要为钙镁石。 50、与热力学计算一致。模拟和实验表明，Na 会使钾鸟粪石不稳定，变成榛石，而 Mg 和 Ca 会形成钙镁石和可能的无定形羟基磷灰石。