摘要
研究了盐湖卤水与干湿循环耦合作用下,纳米偏高岭土对混凝土抗压强度的影响,并利用X射线衍射、红外光谱、压汞实验和扫描电子显微镜-能谱分析对其影响机理进行分析。结果表明:纳米偏高岭土掺量对混凝土盐卤-干湿循环后的抗压强度演变规律影响很大,超过2%的纳米偏高岭土可显著降低混凝土经盐卤-干湿循环后的抗压强度损失率,改善混凝土应用于大温差盐湖地区时的性能。改性机理可归纳为纳米偏高岭土降低了混凝土中的有害孔比例,明显改善了孔径分布,使其原始微观结构更加密实;减小了混凝土中Cl、Na、Mg和S等离子的侵蚀深度和侵入量,进而减轻盐卤溶液中NaCl等盐在混凝土中结晶膨胀产生的物理破坏,减少Mg(OH)2和CaSO4·2H2O等化学腐蚀产物的富集;从而使得混凝土经盐卤-干湿循环后的结构破坏程度明显降低。
The influence of nano-metakaolin on the compressive strength of concrete under the coupled effect of Salt Lake brine and dry-wet cycles was investigated,and the mechanism was analyzed by mercury intrusion analysis,X-ray diffraction,infrared spectroscopy,scanning electron microscopy and energy dispersive spectroscpy.The results show that the proportion of nano-metakaolin has a great effect on the compressive strength of concrete under dry-wet cycles,and more than 2%nano-metakaolin decreases the loss rate of compressive strength.The modification mechanism is since nano-metakaolin reduces the proportion of harmful holes in concrete,improves the pore size distribution and makes the microstructure of concrete more compact.The erosion depth and intrusion amount of Cl,Na,Mg and S ions in concrete are reduced due to the presence of nano-metakaolin,thus decreasing the content of NaCl in the corrosive layer of concrete and preventing the concentration of corrosion products such as Mg(OH)2,and CaSO4·2 H2 O.In consequence,the damage degree of concrete modified by nano-metakaolin with the coupled effect of brine and drying-wetting cycles decreases.
作者
朱绘美
宋强
张军
ZHU Huimei;SONG Qiqng;ZHANG Jun(College of Materials Science and Engineering,Xi'an University of Architecture and Technology,Xi′an 710055,China)
出处
《硅酸盐学报》
EI
CAS
CSCD
北大核心
2020年第2期237-245,共9页
Journal of The Chinese Ceramic Society
基金
"十三五"国家重点研发计划项目(2017YFB0309903)
陕西省自然科学基础研究计划项目(2017JQ5109).
关键词
纳米偏高岭土
混凝土
盐卤-干湿循环
强度
结构
耐久性
nano-metakaolin,concrete,Salt Lake brine and dry-wet cycles,strength,structure
durability
