| 摘要: |
| 为降低大体积混凝土收缩现象，将焙烧菱镁尾矿制成MgO膨胀剂，掺入水泥砂浆中，研究了焙烧温度对MgO膨胀剂矿物组成、晶粒尺寸及活性等的影响.采用X射线衍射仪（XRD）、扫描电镜（SEM）、热分析仪等分析了内掺MgO膨胀剂水泥砂浆的矿物组成、水化进程、热稳定性和微观形貌.结果表明：在菱镁尾矿完全分解的条件（焙烧温度1000℃以上，保温1h）下，随着焙烧温度的提高，MgO晶粒尺寸由276nm增至138.0nm，其活性从708%降至33%，MgO水化速率减慢，晶粒尺寸与其反应活性之间存在线性关系；MgO的活性影响水泥砂浆的膨胀限制率，水泥砂浆试样M C 1000的限制膨胀率最大，在水养20℃条件下，其7、28、120d的限制膨胀率分别为0022%、0037%和0062%.此外，体系中的水化产物Mg（OH）2在基体中呈片层状生长. |
| 关键词: 菱镁尾矿 焙烧温度 MgO膨胀剂 膨胀率 水化进程 |
| DOI：103969/j.issn.1007 9629202103004 |
| 分类号: |
| 基金项目:辽宁科技大学服务地方经济发展项目（LKDFW201802） |
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| Impact of Expansive Agent from Calcinating Magnesite Tailings on Expansion Performance of Cement Mortar |
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LIU Ziyuan1, BI Wanli1, GUAN Yan1, ZHANG Tingting2, CHEN Xiaoyang2
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1.College of Materials and Metallurgy, University of Science and Technology Liaoning, Anshan 114051, China;2.Research Institution of Keda Fengchi Magnesium Building Materials, University of Science and Technology Liaoning, Anshan 114051, China
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| Abstract: |
| In order to reduce the shrinkage cracking of mass concrete, MgO expansive agent was made by calcinating magnesite tailings. The effects of different calcination temperatures on the mineral composition, particle size and activity of MgO expansive agent were studied. The changes of mineral composition, hydration process, thermal stability and micro morphology of cement mortar with MgO expansive agents were studied by means of X ray diffraction, scanning electron microscope and thermal analyzer. The results show that under the condition of complete magnesite decomposition(calcination temperature over 1000℃, and constant temperature for 1h), with the increase of calcination temperature the grain size of magnesium oxide increases from 276nm to 1380nm, the activity decreases from 708% to 33%, and the hydration rate slows down. There is a linear relationship between the grain size of magnesium oxide and the reactivity. MgO activity affects the expansion limit of cement mortar. The expansion limit of cement mortar mixed with MgO expansive agent made of calcination temperature 1000℃ is the largest. Under the condition of 20℃ water curing, the expansion limit of 7, 28,120d can reach 0022%, 0037% and 0062%, respectively. In addition, the hydrated product magnesium hydroxide in the system shows lamellar growth in the matrix. |
| Key words: magnesite tailing calcination temperature MgO expansive agent expansion rate hydration process |
