氧化镁水化产物的微观结构特点表征  

Microstructural characteristics of MgO hydration products

作　　者：卢小琳[1] 兰文改[2] 张洪波[1] 骆菁菁[1] 

机构地区：[1]南京航空航天大学材料学院,江苏南京210016 [2]华北水利水电学院土木与交通学院,河南郑州450011

出　　处：《河海大学学报（自然科学版）》2010年第5期555-558,共4页Journal of Hohai University(Natural Sciences)

基　　金：国家高技术研究发展计划(863计划)项目(2009AA03Z508);国家自然科学基金(60672166);西部交通项目(2009CB01)

摘　　要：为了抑制和降低掺氧化镁混凝土坝的膨胀开裂,采用热分析、X线衍射和扫描电子显微镜分析了氧化镁在不同温度下水化产物的形貌.结果表明：氧化镁在20℃和50℃水中养护180 d后的水化率为57%和94%,经X线衍射分析仍发现未水化的氧化镁;在216℃和2MPa下压蒸4 h,氧化镁全部水化.氧化镁在20℃养护180 d,水化产物为纤维状,长3~5μm,相互交错;掺少量水泥后在80℃水中养护360 d生成针状Mg（OH）2,大小为0.5~1μm,在水化产物中呈分散状扩散和生长;在大量水泥中形成六方板状的Mg（OH）2,大小少于0.1μm,易团聚,能引起混凝土局部膨胀开裂.温度对水化产物性质影响不大,对产物形状、大小和分布有一定的影响.In order to control and mitigate expansion cracks of concrete dams with MgO,the morphological characteristics of MgO hydration products under different temperatures were investigationed by use of the thermal analysis of TG-DSC,X-ray diffraction（XRD） and SEM.The results show that the hydration degrees of MgO cured in water at 20℃ and 50℃ for 180 days are 57% and 94%,respectively, and the XRD analysis gives the existence of some unhydrated MgO.When it is autoclaved at 216℃ under 2 MPa for 4 hours,the MgO is fully hydrated.When the MgO is cured in water at 20℃ for 180 days,the hydration products are fiber-shaped crystals about 3～5 μm in length and interlaced.While the MgO blended with cement of 10% is cured in water at 80℃ for 360 days,the needle-shaped crystals of Mg（OH）2 0.5～1 μm in length are formed,and they spread and develop in the hydration products.As for the MgO blended with cement of 95%,the crystals of Mg（OH）2 become hexahedron-shaped ones less 0.1 μm in length and are easily agglomerated and may cause expansion cracks in local concrete.The curing temperature has little effect on the properties of hydration products but certain effect on their morphology,size and distribution.

关 键 词：氧化镁 微观结构 形貌 水镁石 养护条件 

分 类 号：TQ172[化学工程—水泥工业]