| 摘要: |
| 为探索石灰石粉混凝土在低温硫酸盐环境下生成碳硫硅钙石的机理，将石灰石粉混凝土及采用硫铝酸盐水泥制备的水泥基胶凝材料分别浸泡于质量分数为10%的硫酸镁溶液和碳酸钠溶液中，进行抗压强度测试，并通过扫描电镜(SEM)、X射线衍射(XRD)及红外光谱等微观试验手段，研究并分析了碳硫硅钙石的形成原因.结果表明：低温硫酸镁溶液中的石灰石粉混凝土抗压强度随浸泡时间的延长呈现先增长后减小的趋势，表面出现膨胀剥落现象，生成大量的二水石膏，发生膨胀腐蚀；碳酸钠溶液中的硫铝酸盐水泥基胶凝材料发生了泥化现象，其抗压强度随浸泡时间延长逐渐降低，内部水化产物钙矾石随浸泡时间延长逐渐减少，发生异相结晶转换生成碳硫硅钙石.混凝土中掺加石灰石粉并不是造成碳硫硅钙石型硫酸盐腐蚀(TSA)的主要因素，水泥基胶凝材料硬化体中的钙矾石长期处于含CO2-3环境中才会生成大量烂泥状的碳硫硅钙石，造成胶凝材料破坏. |
| 关键词: 硫酸镁 碳酸钠 碳硫硅钙石 石灰石粉 |
| DOI：103969/j.issn.1007 9629201706004 |
| 分类号: |
| 基金项目:国家自然科学基金资助项目(51374036，51578039) |
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| Mechanism of Formation of Thaumasite in Cement Based Materials in Corrosive Environment |
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LIU Juanhong1, SONG Shaomin2, GAO Meng3
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1.Key Laboratory of HighEfficient Mining and Safety of Metal Mines, Ministry of Education, University of Science and Technology Beijing, Beijing 100083, China;2.Beijing Collaborative Innovation Center of Energy Saving ＆ Emission Reduction Key Technologies, Beijing 100044, China;3.College of Civil Engineering and Architecture, Henan University of Technology, Zhengzhou 450001, China
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| Abstract: |
| In order to elucidate the mechanism of formation of thaumasite from concrete prepared by lime powder under sulfate environment at low temperature, cement based materials made by limestone powder concrete and sulphoaluminate cement were immersed in magnesium sulfate and sodium carbonate solution at 10% mass fraction. The compressive strength was measured, and the microstructure of thaumasite was analyzed by SEM, XRD and infrared spectroscopy. The results show that after soaking in MgSO4 solution at low temperature, the limestone powder concrete occurs flaking phenomenon. The compressive strength increases at first and then decreases with the increase of immersion time. The specimen surface generates a large amount of gypsum due to expansion corrosion. Sulphoaluminates cement based materials with mud can be seen after soaking in Na2CO3 solution, and its compressive strength decreases with the increase of immersion time. Ettringite, the internal hydration product, gradually decreases with the production of heterogeneous silicate crystal and transformation into thaumasite. Mixing limestone powder in concrete is not the main factor to cause TSA(thaumasite sulfate attack)type corrosion. Etrringite in the hardening body of cement based materials in environment containing with carbonate ions for a long time will generate a large amount of sludge like thaumasite and results in damage to the cementitious materials. |
| Key words: magnesium sulfate sodium carbonate thaumasite limestone powder |
