集料对含矿粉混凝土抗硫酸镁侵蚀性能的影响  

Effect of Aggregate on Degradation of Slag Blended Concrete under Magnesium Sulfate Attack

作　　者：吴凯[1,2] 施惠生[1] 徐玲琳[1] 郭晓潞[1] 吕阳[2] 

机构地区：[1]同济大学先进土木工程材料教育部重点实验室,上海201804 [2]根特大学Magnel混凝土研究实验室

出　　处：《建筑材料学报》2016年第3期442-448,共7页Journal of Building Materials

基　　金：国家自然科学基金资助项目(51378390;51402216);同济大学青年优秀人才培养行动计划项目(2014KJ060);硅酸盐建筑材料国家重点实验室开放基金重点项目(SYSJJ2016-01)

摘　　要：对大掺量矿粉(质量分数70%)和不同体积分数集料混凝土试件在浓度为42.4g/L的MgSO_4溶液侵蚀作用下表观损伤、线膨胀率、质量和相对动弹模量变化情况进行监测,并结合背散射电子图像、能谱扫描和压汞等微观结构分析结果,研究了大掺量矿粉和集料对混凝土抗硫酸镁溶液侵蚀性能的影响机理.结果表明:尽管矿粉有助于细化硬化浆体孔结构并提高混凝土的抗渗性能,但大掺量矿粉会降低Ca(OH)_2含量,加快体系中C-S-H的分解和M-S-H生成,不利于提高其抗硫酸镁溶液侵蚀的能力.在高浓度硫酸镁溶液环境中,膨胀性产物石膏易于临近集料区域沉积,使混凝土的损伤破坏程度随集料体积分数的增加而有所增大.在针对抗硫酸镁溶液侵蚀混凝土组成设计时,需综合考虑胶凝材料及水化产物组成、硬化浆体孔结构的共同影响.The influence of slag and aggregate volume content in concrete on the degradation,linear expansion,mass change and relative elastic dynamic modulus of concrete exposed to 42.4g/L MgSO4 solution were investigated.The microstructures of sound and deteriorated concrete were also determined using backscattered electron imaging analysis（BSE-IA）,energy dispersive X-ray spectroscopy analysis（EDS）and mercury intrusion porosimetry（MIP）.Results show that the addition of slag is able to refine the pore structure and increase the impermeability of corresponding cement-based materials.However,the incorporation of high amount of slag exerts an adverse effect on magnesium sulfate resistance of concrete by reducing calcium hydroxide,promoting the decalcification of C-S-H and the formation of M-S-H.It is found in BSE-EDS analysis that the preferable deposition of gypsum in the region close to aggregate could be the reason for the severe degradation of specimens made with a relative high amount of aggregate at a high concentration of magnesium sulfate.Therefore,the mix design of concrete which is supposed to serve in the magnesium sulfate environment should consider the influence of porosity,compositions of cementitious materials and those of hydration products in a comprehensive way.

关 键 词：集料 矿粉 硫酸镁溶液侵蚀 孔结构 背散射电子图像 

分 类 号：TU528.33[建筑科学—建筑技术科学]