氯离子环境下钙矾石和水化硅酸钙体系铝配位分布
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摘要
通过化学合成钙矾石和水化硅酸钙,利用XRD、27 Al核磁共振测试手段,研究了氯离子环境下钙矾石(AFt)和水化硅酸钙(C-S-H)凝胶体系中铝配位分布规律。结果表明,在C-S-H凝胶和氯离子共存环境中,第三类水化铝酸盐(TAH)凝胶中六配位铝(Al[6])首先转化为四配位铝(Al[4])进入C-S-H结构,且Al[4]总量不受C-S-H钙硅比限制;同时氯离子不影响Al[6]-TAH向Al[4]转化,当达到C-S-H凝胶容纳Al[4]的极限时,剩余的Al[6]-TAH才与氯离子反应形成Friedel盐(F盐)。TAH比AFt更容易与氯离子反应形成F盐;低钙硅比C-S-H环境不利于TAH与氯离子结合,但利于钙矾石分解并与氯离子反应生成F盐。
The distribution of aluminum coordination in the ettringite and C-S-H gels system under chloride ions environment was investigated through chemical synthesis of ettringite and C-S-H gels and by XRD,27 Al Nuclear Magnetic Resonance(NMR).The results indicate that in the coexistence environment of C-S-H gels and chloride ions,the 6-coordination aluminum(Al[6])in the TAH(third aluminum hydrate)gels firstly transforms into the 4-coordination aluminum(Al[4])entering into C-S-H structure,and the total amount of Al[4]in that C-S-H is not restricted by the Ca/Si ratio of them;meanwhile,the transformation from Al[6]-TAH to Al[4]is not influenced by chloride ions,and the remainder Al[6]-TAH reacts with chloride ions to form the Friedel's salts(F's),when the amount of Al[4]reaches the capability limit of C-S-H gels.Furthermore,the reaction of TAH with chloride ions is more easier than that of ettringite to form the F's,and the environment of low Ca/Si ratio C-S-H gels does not favor for the reaction of the TAH with chloride ions,on the contrary,it promotes the decomposition of ettringite to form the F's in environment of chloride ions.
The distribution of aluminum coordination in the ettringite and C-S-H gels system under chloride ions environment was investigated through chemical synthesis of ettringite and C-S-H gels and by XRD,27 Al Nuclear Magnetic Resonance(NMR).The results indicate that in the coexistence environment of C-S-H gels and chloride ions,the 6-coordination aluminum(Al[6])in the TAH(third aluminum hydrate)gels firstly transforms into the 4-coordination aluminum(Al[4])entering into C-S-H structure,and the total amount of Al[4]in that C-S-H is not restricted by the Ca/Si ratio of them;meanwhile,the transformation from Al[6]-TAH to Al[4]is not influenced by chloride ions,and the remainder Al[6]-TAH reacts with chloride ions to form the Friedel's salts(F's),when the amount of Al[4]reaches the capability limit of C-S-H gels.Furthermore,the reaction of TAH with chloride ions is more easier than that of ettringite to form the F's,and the environment of low Ca/Si ratio C-S-H gels does not favor for the reaction of the TAH with chloride ions,on the contrary,it promotes the decomposition of ettringite to form the F's in environment of chloride ions.
引文
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[18]Fernndez-Jiménez A,Palomo A,Sobrados I,et al.The role played by the reactive alumina content in the alkaline activation of fly ashes[J].Micropor Mesopor Mat,2006,91(1):111-119.
[19]Jin Zuquan,Sun Wei,Li Qiuyi,et al.Bonding performance of mineral admixture to chloride in sea water[J].Corrosion and Protection,2009,30(12):869-873(in Chinese).金祖权,孙伟,李秋义,等.矿物掺合料对海水中氯离子的结合能力[J].腐蚀与防护,2009,30(12):869-873.
[2]Wang Xiaogang,Shi Caijun,He Fuqiang,et al.Chloride binding and its effects on microstructure of cement-based materials[J].J Chin Ceram Soc,2013,41(2):187-198.王小刚,史才军,何富强,等.氯离子结合及其对水泥基材料微观结构的影响[J].硅酸盐学报,2013,41(2):187-198.
[3]Mehta P K.Effect of cement composition on corrosion of reinforcing steel in concrete[J].Astm Special Technical Publications,1977,264(11-12):1051-1058.
[4]Glasser F P.Role of chemical binding in diffusion and mass transport[C].Toronto:International Conference on Ion and Mass Transport in Cement-Based Materials,1999:154.
[5]Balonis M,Lothenbach B,Saout G L,et al.Impact of chloride on the mineralogy of hydrated Portland cement systems[J].Cem Concr Res,2010,40(7):1009-1022.
[6]Ekolu S O,Thomas M D A,Hooton R D.Pessimum effect of externally applied chlorides on expansion due to delayed ettringite formation:Proposed mechanism[J].Cem Concr Res,2006,36(4):688-696.
[7]Monteiro P,Wang K,Sposito G,et al.Influence of mineral admixtures on the alkali-aggregate reaction[J].Cem Concr Res,1997,27(12):1899–1909.
[8]Nagataki S,Otsuki N,Wee T H,et al.Condensation of chloride ion in hardened cement matrix materials and on embedded steel bars[J].ACI Mater J,1993,90(4):323-332.
[9]Larsen C K.Chloride binding in concrete effect of surrounding environment and concrete composition[D].Norway:The Norwegian University of Science and Technology,1998.
[10]Laidler K J,Meiser J K.Physical Chemistry[M].California:The Benjamin Cummings Publishing Company,1982:123-778.
[11]Barbarulo R,Peycelon H,Leclercq S.Chemical equilibria between C-S-H and ettringite,at 20and 85℃[J].Cem Concr Res,2007,37(8):1176-1181.
[12]Andersen M D,Jakobsen H J,Skibsted J.Incorporation of aluminum in the calcium silicate hydrate(C-S-H)of hydrated Portland cements:A high-field 27 Al and 29Si MAS NMR investigation[J].Inorg Chem,2003,42(7):2280-2287.
[13]Andersen M D,Jakobsen H J,Skibsted J.A new aluminium-hydrate species in hydrated Portland cements characterized by 27 Al and 29Si MAS NMR spectroscopy[J].Cem Concr Res,2006,36(1):3-17.
[14]Hu Chenguang.Effect of temperature and sulfate attack on microstructure of C-S-H in Portland cement pastes with fly ash[D].Wuhan:Wuhan University of Technology,2014(in Chinese).胡晨光.温度和硫酸盐侵蚀对粉煤灰水泥浆体C-S-H微结构的影响研究[D].武汉:武汉理工大学,2014.
[15]Ding Q J,Hu C G,Feng X X,et al.Effect of curing regime on the distribution of Al 3+coordination in hardened cement pastes[J].Journal of Wuhan University of Technology-Mater.Sci.Ed.,2013,28(5):927-933.
[16]Cody A M,Lee H,Cody R D,et al.The effects of chemical environment on the nucleation,growth,and stability of ettringite[Ca3Al(OH)6]2(SO4)3·26H2O[J].Cem Concr Res,2004,34(6):869-881.
[17]Birnin-Yauril U A,Glasser F P.Friedel’s salt,Ca2Al(OH)6(Cl,OH)·2H2O:its solid solutions and their role in chloride binding[J].Cem Concr Res,1998,28(12):1713-1723.
[18]Fernndez-Jiménez A,Palomo A,Sobrados I,et al.The role played by the reactive alumina content in the alkaline activation of fly ashes[J].Micropor Mesopor Mat,2006,91(1):111-119.
[19]Jin Zuquan,Sun Wei,Li Qiuyi,et al.Bonding performance of mineral admixture to chloride in sea water[J].Corrosion and Protection,2009,30(12):869-873(in Chinese).金祖权,孙伟,李秋义,等.矿物掺合料对海水中氯离子的结合能力[J].腐蚀与防护,2009,30(12):869-873.