MgSO_4腐蚀环境作用下混凝土的抗冻性  

Frost Resistance of Concrete under Action of Magnesium Sulfate Attack

作　　者：张云清[1,2] 余红发[1] 孙伟[3] 张建业 

机构地区：[1]南京航空航天大学土木工程系,江苏南京210016 [2]南京农业大学工学院,江苏南京210031 [3]东南大学材料科学与工程学院,江苏南京211189 [4]中国土木工程集团有限公司,北京100038

出　　处：《建筑材料学报》2011年第5期698-702,共5页Journal of Building Materials

基　　金：国家重点基础研究发展计划(973计划)项目(2009CB623203);江苏省自然科学基金前期预研项目(BK2005216);2008年江苏省"六大人才高峰"高层次人才项目;南京航空航天大学博士生创新基金资助项目(BCXJ07-04)

摘　　要：采用快冻法研究了高强的混凝土(HSC)、大掺量矿物掺合料混凝土(HVMAC)和掺入引气剂、高效减水剂、混杂纤维和膨胀剂的高耐久性混凝土(HDC)在水、5%(质量分数)MgSO_4溶液中的抗冻性能.结果表明:对于高水胶比、低掺量矿物掺合料HSC,MgSO_4溶液因冰点降低效应、化学腐蚀反应产物填充混凝土表层的毛细孔对试件表层的密实强化作用以及对混凝土内部的保护作用,能够显著缓解其冻融破坏;对于低水胶比的HVMAC,MgSO_4化学腐蚀反应形成的氢氧化镁和石膏等膨胀性产物,使冻融时HPC内部形成AFt所产生的微裂纹进一步扩展、贯通,反而加速了其冻融破坏作用.基于低水胶比HVMAC的配制技术,掺入引气剂、混杂纤维和膨胀剂,可显著提高HDC的抗冻性能,尤其是提高MgSO_4腐蚀环境作用下的抗冻性能,其水中冻融循环为625次,而在5%MgSO_4溶液腐蚀环境作用下,其冻融循环大于900次.Abstract： Through the method of accelerated freeze-thaw, the freeze-thaw durability of three kinds of con- cretes subjected to water and 5% （by mass） MgSO4 solution was studied. The concretes studied include high strength concrete（HSC）, high-volume mineral admixture concrete（HVMAC） and high durable con- crete（HDC） with high-volume mineral admixture, air-entraining agent, superplasticizer, fibers and expan- sion agent added. Results show that for higher water binder ratio, lower content of mineral admixture of HSC, MgSO4 solution can significantly alleviate the freeze＇-thaw damage because of lowering effect of Mg- SO4 solution freezing point. Chemical corrosion products fill the pores in the concrete surface to protect and strengthen. For lower water binder ratio of HVMAC, MgSO4 chemical reaction leads to formation of expansion products, such as magnesium hydroxide and gypsum, etc. , which further promote the internal formation of AFt by freezing and thawing, leading to the propagation and coalescence of micro-cracks, but the freeze-thaw damage of.HPC is accelerated. Based on low water cement ratio of HVMAC of preparation techniques, the frost resistance of HDC, especially under the corrosive action of MgSO4, prepared by highly efficient air-entraining, hybrid fibers and expansive agent can be significantly improved. Freezethaw cycles of HDC is 625 times in water, and more than 900 times in 5% MgSO4 Corrosion solution.

关 键 词：混凝土 硫酸盐腐蚀 镁盐腐蚀 抗冻性 相对动弹性模量 

分 类 号：TU528.01[建筑科学—建筑技术科学]