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研究了固化模拟放射性核素Sr对磷酸镁水泥性能的影响,通过分析固化体水化热、物相组成及微观形貌,探讨了Sr对磷酸镁水泥水化特性的影响机理。结果表明:固化体的力学性能优异,1 d抗压强度即可达到国家标准的4.5倍以上;磷酸镁水泥固化体具有优异的抗浸出性,42 d浸出率及累计浸出分数远低于国家标准的要求;Sr会阻碍磷酸盐在水化初期的水解及电离,同时MgO溶解及水化产物MgKPO_4·6H_2O生成的速率随Sr掺量增大而减缓;掺入Sr后水化产物生成量大幅下降是水化初期抗压强度降低的主要原因,随着龄期增长,水化产物结晶程度降低、结构改变以及孔隙孔径增大成为固化体抗压强度降低的主要原因。
The influence of curing simulated radionuclide Sr on the performance of magnesium phosphate cement was studied. The influence mechanism of Sr on the hydration characteristics of magnesium phosphate cement was discussed by analyzing the hydration heat, phase composition and microstructure of the cured cement. The results show that the mechanical properties of the cured body are excellent and the compressive strength at 1 d can reach 4.5 times higher than the national standard. The magnesium phosphate cement cured body has excellent anti-leaching performance, the leaching rate at 42 days and the cumulative leaching fraction are far below the national standards . Sr could hinder the hydrolysis and ionization of phosphate during the initial hydration process. Meanwhile, the dissolution rate of MgO and the rate of MgKPO 4 · 6H 2 O formation slowed down with the increase of Sr content. The formation of hydration products significantly decreased after Sr addition Is the main reason for the decrease of compressive strength at the initial stage of hydration. As the age increases, the degree of crystallinity of the hydration product decreases, and the structural change and the increase of the pore diameter become the main reasons for the decrease of the compressive strength of the cured body.