The immobilisation mechanism of Pu(IV) by Portland cement-based material is not well understood. This study aims to reveal the immobilisation mechanism and occurrence status of Ce(IV) (chemical analogue of Pu(IV)) in Portland cement paste. The addition of Ce(NO) first slightly retarded then accelerated the early-age hydration of Portland cement, thereby resulting in an increase of compressive strength by 29 %. The main contributor to immobilisation of Ce is Portland cement rather than zeolite. The hydration products were not altered by Ce(NO) addition, whereas the hydration degree and mean chain length of C-(Al/Ce)-S-H increased. Over 99.99 % of Ce was immobilised by synthesised C-S-H. A analysis of the synthesised C-S-H confirmed the formation of C-Ce-S-H, where Ce tetrahedra took the bridging site of silicate chain of C-Ce-S-H. Nano-crystalline CeO grains were identified, which intermixed with C-Ce-S-H. Approximately 90 % of Ce were immobilised by C-Ce-S-H, and the rest exist as nano-crystalline CeO grains.

中文翻译：

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关于硅酸盐水泥中 Ce(IV) 固定化的新见解：Ce 的性质、水化、微观结构和赋存状态

波特兰水泥基材料对 Pu(IV) 的固定机制尚不清楚。本研究旨在揭示硅酸盐水泥浆体中Ce(IV)（Pu(IV)的化学类似物）的固定机制和赋存状态。 Ce(NO)的添加首先稍微延迟然后加速波特兰水泥的早期水化，从而导致抗压强度增加29%。 Ce 固定的主要贡献者是波特兰水泥而不是沸石。 Ce(NO)的添加没有改变水化产物，而C-(Al/Ce)-SH的水化程度和平均链长增加。合成的 CSH 固定了超过 99.99% 的 Ce。对合成的 CSH 的分析证实了 C-Ce-SH 的形成，其中 Ce 四面体占据了 C-Ce-SH 硅酸盐链的桥接位点。鉴定出纳米晶 CeO 晶粒，它与 C-Ce-SH 混合。大约90%的Ce被C-Ce-SH固定，其余的以纳米晶CeO晶粒形式存在。