硫酸盐侵蚀条件下C-(A)-S-H组成-结构演化的量化分析  

Composition and Nano-structure of C-(A)-S-H Gels in Cement Pastes after Sulphate Attack

作　　者：朱效宏 李青 陈平[1] 康晓娟 杨凯 杨长辉[3] ZHU Xiaohong;LI Qing;CHEN Ping;KANG Xiaojuan;YANG Kai;YANG Changhui(College of Civil and Architectural Engineering,Guilin University of Technology,Guilin 541004,Guangxi,China;School of Civil Engineering,University of Leeds,Leeds LS29JT,UK;College of Materials Science and Engineering,Chongqing University,Chongqing 400045,China;Department of Civil Engineering,The University of Hong Kong,Hong Kong 999077,China)

机构地区：[1]桂林理工大学土木与建筑工程学院,广西工程结构与建筑节能重点实验室,广西桂林541004 [2]利兹大学土木工程学院,英国利兹LS29JT [3]重庆大学材料科学与工程学院,重庆400045 [4]香港大学土木工程系,中国香港999077

出　　处：《硅酸盐学报》2021年第5期901-909,共9页Journal of The Chinese Ceramic Society

基　　金：广西创新驱动重大专项(2018AA23004);桂科能(19-J-22-3);桂科能(19‒J‒21‒12);桂科(AA18242007‒3)。

摘　　要：采用Fourier变换红外光谱、综合热分析、29Si魔角自旋核磁共振及透射电镜‒能谱等方法,研究了5%MgSO_(4)(质量分数)溶液干湿循环作用下硅酸盐水泥及高抗硫酸盐水泥砂浆中水化硅酸钙凝胶(C-(A)-S-H)结构变化。结果表明:硫酸盐易侵蚀C-(A)-S-H凝胶中[AlO4]桥氧四面体,[SiO4]长链中Q1(二聚体或硅链尾端)也易受MgSO_(4)侵蚀形成M/C-(A)-S-H凝胶;硫酸根与阳离子桥接,形成–Si–O–M^(2+)–1/2SO_(4)^(2–)结构吸附于C-(A)-S-H凝胶表层。采用托贝莫来石/羟基硅钙石混合模型(T/J model)推演了硅酸盐水泥和高抗硫酸盐水泥中C-(A)-S-H凝胶在MgSO_(4)溶液中干湿循环后的结构差异,给出了侵蚀后C-(A)-S-H组成化学式。提升抗MgSO_(4)侵蚀能力在于控制膨胀产物(石膏及AFt)及C-(A)-S-H凝胶中[AlO_(4)]桥氧四面体含量。The nano-structural change of hydrated calcium silicate gels(C-(A)-S-H)in Portland cement(PC)and high-sulphate resistance cement(HSR)mortars under wetting-drying cycling conditions in 5%(mass fraction)MgSO_(4)solution was investigated by Fourier-transform infrared spectroscopy(FTIR),thermogravimetry-tifferential scanning calorimetry(TG-DSC),29Si magic-angle spinning nuclear magnetic resonance(MAS-NMR),and transmission electron microscopy-energy dispersive X-ray spectroscopy(TEM-EDX).The results show that Al-tetrahedra in C-(A)-S-H phase is plausibly the weakness during sulphate attack,the Q1(dimer or end-member in the chain)in the main aluminosilicate tetrahedral chain can be easily attacked by MgSO_(4)to form M/C-(A)-S-H,and sulphate ions are easily absorbed on the surface of C-(A)-S-H through–Si–O–^(M2+)-1/2SO_(4)^(2–).The chemical compositions of C-(A)-S-H in all the samples before and after sulphate attack were simulated by the tobermorite/jennite(T/J)model.The difference between the nano-structural and the average compositional formulas of C-(A)-S-H gels in two cements after sulphate attack was derived from the(T/J)model.It is necessary for the improvement of the resistance of motors against MgSO_(4)attack to restrict the expansive corrosion products(i.e.,gypsum and AFt)and Al-tetrahedra in the aluminosilicate chain of C-(A)-S-H phase.

关 键 词：硫酸镁溶液 硫酸盐侵蚀 水化硅酸钙凝胶 硅氧四面体 结构演变 水泥砂浆 

分 类 号：TU528[建筑科学—建筑技术科学]