| 摘要: |
| 从早期硬化强度发展、水化离子溶出规律、水化放热行为以及水化物相和微观形貌层次阐述了液体无碱速凝剂对硅酸盐水泥早期水化的影响.结果表明：液体无碱速凝剂通过速凝阶段针棒状钙矾石的迅速形成而使得硅酸盐水泥初始水化放热显著提高；氟离子的引进促进了速凝阶段C3S的快速溶解水化并形成C S H凝胶，明显改善了无碱速凝剂的速凝作用效果及其与减水剂的适应性，但显著降低了水化24h的硬化体强度，原因是氟离子在水化加速阶段消耗钙离子而形成了片状CaF2产物，在吸附插层作用下对C S H凝胶产生包裹抑制作用，从而明显延缓了水泥水化过程. |
| 关键词: 含氟无碱速凝剂 硅酸盐水泥 早期水化 氟化钙 钙矾石 |
| DOI：103969/j.issn.1007 9629202101005 |
| 分类号: |
| 基金项目:国家重点研发计划(2020YFC1909900)；国家自然科学基金杰出青年基金资助项目(51825203)；中国铁路总公司科技研究开发计划课题(N2018G030)；江苏省第十五批六大人才高峰项目(JZ 058) |
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| Effect of Alkali Free Accelerators on Early Age Hydration of Portland Cement |
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ZENG Luping1, QIAO Min1, WANG Wei1, RAN Qianping2, HONG Jinxiang1
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1.State Key Laboratory of High Performance Civil Engineering Materials, Jiangsu Sobute New Materials Co., Ltd., Nanjing 211103, China;2.School of Materials Science and Engineering, Southeast University, Nanjing 211189, China
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| Abstract: |
| Early age hydration behavior of Portland cement containing liquid alkali free accelerators was studied by early age hydrated strength development, released ionic concentration, isothermal calorimetry, hydration phase analysis and microstructure analysis. The results show that the initial hydration heat rate of Portland cement containing liquid alkali free accelerators rises sharply due to the fast crystallization of massive ettringite prisms. The fluoride present in alkali free accelerators promotes C3S dissolution and C S H gel generation, leading to better quick setting effect and improved compatibility with superplasticizers. However, the hardening strength of cement paste hydrated 24h is declined notably with fluorine containing alkali free accelerator, mainly due to the crystallization of plate like CaF2, which absorbs and intercalates into the C S H gel structure and induces delayed hydration process. |
| Key words: fluorine containing alkali free accelerator Portland cement early age hydration calcium fluoride ettringite |
