硫酸镁对碳硫硅钙石形成的影响.pdf

学免兔ww.xtnt.com
2014年第1(总第301期)
凝
原材料及辅助物料
Nurhber ]1 in 2014(Total No 301)
Concrete
MATER【 AL ANU) ADMINICLE
doi:10.3969/5isa.1002-3550.2014.1,018
酸镁对碳硫硅钙石形成的影响
肖,吴婷,郭庆伟,孟庆业,郭明稱
(中南大学土木工程学廃、湖南长沙41005)
摘要:研究了硫酸镁对水泥基胶凝材料中硫徒钙在羏放的影响。将水泥一石灰石粉净浆试件浸泡在5℃下,5%MgSO溶液
中,观察试件侵蚀后的外观,并对腐蚀产物进行文射线行射、红外光谱分析。结果表明,在5%MgSO,溶液中,纯水泥净浆试件发生
硫酸盐腐蚀,表面有白色物旑生成,腐蚀产物以氢氧化镁、石膏和水化硅酸镁为主;水泥一石灰石粉净浆试件在S%MgSO.溶液中发
牛碳硫徒钙石蓼酸盐腐蚀,随着时闾的延长而日益严重,由表及里逐渐变为一种无胶凝性的烂泥状物质,腐蝕产物以碳硫硅钙石
和石膏为主。硫酸镁能够加快碳硫硅钙石的形成遠度
关键词:硫酸镁;硫酸盐侵蚀龖锍砫钙石;机理
中图分类号:TUS2,04
文献标志码:A文章编号:102-3550(2014)11-0070-04
E#eet of Mgso 8i thaumasite
tion
XIAO Jia, WU Ting, GUO Qingwei, MENG Qingye, GUO Minglei
(School of Civil Engineering, Central South University, Changsha 410075, China
Abstract: The efect of Mgso mn Imation of thaumasite in men based emei ious matetials was studied. The cement-ground
limestone pastes were immerged in 5% Mgso solution, and the appearance of corroded pastes was obscrved. Besides, the corrosion prod-
ucts were also characterized by X-ray di ration and inad spe um. the rcsuits showed that the pure cement pastes which were im
merged in S% Mgso, solution were eroded by sulphate and the surface was covered by white material, where the corrosion products were
mainly Mg(OH) gypsum and magnesium silicate hydra es. The cemen- round limestone pastes immerged in 5%Mgso, solution were
damaged by thaumasite fotfmn of sulfate attack(TSA)badly and the damage condition became more and more serious as time evolved, then
the pastes gradually became non-cementitious muddy material from the outside to the inside. The corosion products were mainly thauma
site and gypsum, and Mgso can accelerate the speed of thaumasite formation
Key words: magnesium sulfate; sulfate attack; thaumasite; mechanism
结构、形成反应机理、影响因素和预防措施等方面已相继
展开了系统研究?,而我国日前研究主要集中在外界环
碳硫硅钙石型硫酸盐侵蚀( Thaumasite sulfate attack,境、矿物掺合料、硫酸根离子、磯酸根离子、氯离子以及两
简称TSA)是一种新型的硫酸盐腐蚀,碳硫硅钙石早在20两组合的复合溶液对碳硫硅钙石形成的影响,对镁盐
世纪60年代就被发现存在于受硫酸盐和碳酸盐共同侵蚀影响碳硫硅钙石形成的规律研究较少。
后的水泥石中,但是仅作为一种矿物被报道叫,未引起人们
因此,本试验研究了硫酸镁对碳硫硅钙石形成的影响,
的重视,直到90年代英国政府组织专家对英国境内的“碳
并分析了硫酸镁对掺有石灰石粉的水泥净浆的腐蚀机理
硫硅钙石型硫酸盐侵蚀”进行调査和分析,人们才真正意
识到TSA破坏的严重性。研究P表明水泥基材料碳硫硅1原材料及试验方法
钙石型硫酸盐腐蚀容易在低温(通常<15℃)、高湿、硫酸
盐、碳酸盐、碱性(pH>10.5)等环境下发生,主要是使水泥1.1原材料
石中C-SH凝胶转变为一种灰白色、无胶结能力的泥状物
水泥采用北京兴发水泥有限公司生产的P·142.5级
质,导致水泥石强度降低甚至崩溃,其危害性比传统硫酸拉法基瑞安基准水泥,其物理性能和化学成分如表1、2所
盐腐蚀更为严重。由于其破坏性大、分布广泛,水泥混凝土示;石灰石粉采用湖南华西投资有限公司产1250目重质
碳硫硅钙石型硫酸盐侵蚀问题成为近年来混凝土科学领碳酸钙粉,其比表面积为729m3kg,密度为2.75gcm;水
域的热点研究课题之一。目前,国外对碳硫硅钙石的组成采用自来水。
收稿日期:2014-05-05
基金项目:国家自然科学基金项目(51278497
70