氯盐-硫酸盐共存环境中阳离子类型对氯离子结合能力的影响
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摘要
选用KCl、Na Cl、CaCl_2、Mg Cl_2四种氯盐,对预埋钢筋的水泥砂浆圆柱体试件进行浸烘循环试验,研究氯盐-硫酸盐共存环境中阳离子类型对氯离子结合能力的影响。采用电位滴定法进行氯离子浓度测试,X射线衍射仪用于定性分析胶凝材料的水化产物,同时利用综合热分析仪进行微分热重法定量分析水化产物。研究结果表明,在氯盐-硫酸盐共存环境中,阳离子类型对孔溶液的p H值和氯离子结合能力有显著影响,其影响能力大小为Mg~(2+)>Ca~(2+)>K~+>Na~+;K~+、Na~+均会导致孔溶液的p H值升高,使Friedel′s盐中结合氯离子被重新释放,从而降低氯离子结合能力;Mg~(2+)、Ca~(2+)、SO_4~(2-)共存时,会生成石膏、钙矾石等膨胀性产物,导致结构内部形成微裂缝,加速了氯离子的渗透,导致自由氯离子含量迅速升高;但Mg~(2+)、Ca~(2+)的存在能够产生较多的M-S-H、C-S-H凝胶,从而增加了物理吸附氯离子含量,氯离子结合能力随之提高。
Four kinds of chloride salt KCl,Na Cl,Ca Cl_2and Mg Cl_2were selected to perform a wet-drying circulation test on the embedded reinforced cement mortar cylinder specimens to study the effect of the cation type on chloride binding capacity in the chloride-sulfate coexistence environment.The potentiometric titration method was used to measure the concentration of chloride ion.The X-ray diffraction was used to qualitatively analyze the hydration products of cementitious materials.At the same time,a differential thermal analysis method was used to quantitatively analyze the hydration products.The results showed that chloride binding capability and the p H value of pore solution were greatly affected by chloride cation type,with binding capability of Mg~(2+)>Ca~(2+)>K~+>Na~+.K~+and Na~+lead to the rise of the p H value of pore solution,increasing the solubility of Friedel′s salt to release the bound chlorides,so as to reducing the chloride binding capacity.When Mg~(2+),Ca~(2+)and SO_4~(2-)coexist,the expansive products such as gypsum and calcium vanadium will be produced,resulting in the formation of micro cracks in the structure,so as to accelerating the penetration of chlorine ions and increasing the content of free chlorine ions rapidly.However,Mg~(2+)and Ca~(2+)can also produce more M-S-H and C-S-H gels,which will increase the physical adsorption of chloride ions and the chloride binding capacity.
Four kinds of chloride salt KCl,Na Cl,Ca Cl_2and Mg Cl_2were selected to perform a wet-drying circulation test on the embedded reinforced cement mortar cylinder specimens to study the effect of the cation type on chloride binding capacity in the chloride-sulfate coexistence environment.The potentiometric titration method was used to measure the concentration of chloride ion.The X-ray diffraction was used to qualitatively analyze the hydration products of cementitious materials.At the same time,a differential thermal analysis method was used to quantitatively analyze the hydration products.The results showed that chloride binding capability and the p H value of pore solution were greatly affected by chloride cation type,with binding capability of Mg~(2+)>Ca~(2+)>K~+>Na~+.K~+and Na~+lead to the rise of the p H value of pore solution,increasing the solubility of Friedel′s salt to release the bound chlorides,so as to reducing the chloride binding capacity.When Mg~(2+),Ca~(2+)and SO_4~(2-)coexist,the expansive products such as gypsum and calcium vanadium will be produced,resulting in the formation of micro cracks in the structure,so as to accelerating the penetration of chlorine ions and increasing the content of free chlorine ions rapidly.However,Mg~(2+)and Ca~(2+)can also produce more M-S-H and C-S-H gels,which will increase the physical adsorption of chloride ions and the chloride binding capacity.
引文
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[14]YUAN Q,SHI C J,DE SCHUTTER G,et al.Chloride binding of cement-based materials subjected to external chloride environment:a review[J].Construction and Building Materials,2009,23(1):1-13.
[15]PRUCKNER F,GJ覫RV O E.Effect of CaCl2and NaCl additions on concrete corrosivity[J].Cement and Concrete Research,2004,34(7):1209-1217.
[16]蒋林华,刘蓉,莫莉莉,等.阳离子类型对混凝土中钢筋腐蚀临界氯离子浓度的影响[J].江苏大学学报(自然科学版),2013,34(4):476-480.
[17]ZHU Q,JIANG L H,CHEN Y,et al.Effect of chloride salt type on chloride binding behavior of concrete[J].Construction and Building Materials,2012(37):512-517.
[18]水工混凝土试验规程:SL 352-2006[S].
[19]PAGE C L.Mechanism of corrosion protection in reinforced concrete marine structures[J].Nature,1975(258):514-515.
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[21]ANSSON C M,FRLUNDT,MARKUSSEN J B.The effect of chloride cation type on the corposion of steel in concrete by chloride salts[J].Cement and Concrete Research,1985,15(1):65-73.
[22]XU Y.The influence of sulphates on chloride binding and pore solution chemistry[J].Cement and Concrete Research,1997,27(12):1841-1850.
[23]Michel M,GEORGIN J,AMBROISE J.Improving the mechanical performance of high-grade slag cement by the addition of Portland cement and sulfoaluminate cement[J].Construction and Building Materials,2012(37):291-300.
[24]SURYAVANSHI A K,NARAYAN SWAMY R.Stability of Friedel′s salt in carbonated concrete structural elements[J].Cement and Concrete Research,1996,26(5):729-741.
[25]HOSSAIN K M A,LACHEMI M.Performance of volcanic ash and pumice based blended cement concrete in mixed sulfate environment[J].Cement and Concrete Research,2006,36(6):1123-1133.
[26]ZHANG M,CHEN J,LV Y,et al.Study on the expansion of concrete under attack of sulfate and sulfate chloride ions[J].Construction and Building Materials,2013(39):26-32.
[27]LUO R,CAI Y,WANG C,et al.Study of chloride binding and diffusion in GGBS concrete[J].Cement and Concrete Research,2003,33(1):1-7.
[28]GUERRERO A,GOI S,ALLEGRO V R.Effect of temperature on the durability of class C fly ash belite cement in simulated radio active liquid waste:synergy of chloride and sul-phate ions[J].Hazard.Mater,2009,165(1-3):903-908.
[2]邢锋,张小刚,霍元,等.砂浆中细骨料携带氯离子腐蚀机理与强度规律[J].建筑材料学报,2008,11(2):201-206.
[3]LI F M,YUAN Y S,LI C Q.Corrosion propagation of prestressing steel strands in concrete subject to chloride attack[J].Construction and Building Materials,2011,25(10):3878-3885.
[4]Abd El.AZIZA M,Abd El.ALEEM S,HEIKAL M,et al.Hydration and durability of sulphate-resisting and slag cement blends in Caron′s Lake water[J].Cement and Concrete Research,2005,35(8):1592-1600.
[5]Daniel E.Kejin Wang,Wilfrid A.Nelsen,Nixon.Damaging effects of deicing chemicals on concrete materials[J].Cement and Concrete Composites,2006(28):173-188.
[6]REDDY B,GLASS G K,LIM P J,et al.On the corrosion risk presented by chloride bound in concrete[J].Cement and Concrete Composites,2002,24(1):1-5.
[7]GLASS G K,BUENFELD N R.The influence of chloride binding on the chloride induced corrosion risk in reinforced concrete[J].Corrosion Science,2000,42(2):329-344.
[8]金祖权,孙伟,张云升,等.氯盐、硫酸盐作用下高性能混凝土损伤研究[J].工业建筑,2005,35(1):5-7.
[9]XU Y.The influence of sulfate on chloride binding and pore solution chemistry[J].Cement and Concrete Research,1997(27):1841-1850.
[10]陈晓斌,唐孟雄,马昆林.地下混凝土结构硫酸盐及氯盐侵蚀的耐久性试验[J].中南大学学报(自然科学版),2012,43(7):2803-2812.
[11]庄其昌,金祖权,李凤梅.钢筋在混凝土模拟孔溶液中的腐蚀行为研究[J].青岛理工大学学报,2010,31(3):12-16.
[12]GENG J,EASTERBROOK D,LI L Y,et al.The stability of bound chlorides in cement paste with sulfate attack[J].Cement and Concrete Research,2015(68):211-222.
[13]BROWN P W,STEVEN B.The distributions of bound sulfates and chlorides in concrete subjected to mixed NaCl,MgSO4,Na2SO4attack[J].Cement and Concrete Research,2000,30(10):1535-1542.
[14]YUAN Q,SHI C J,DE SCHUTTER G,et al.Chloride binding of cement-based materials subjected to external chloride environment:a review[J].Construction and Building Materials,2009,23(1):1-13.
[15]PRUCKNER F,GJ覫RV O E.Effect of CaCl2and NaCl additions on concrete corrosivity[J].Cement and Concrete Research,2004,34(7):1209-1217.
[16]蒋林华,刘蓉,莫莉莉,等.阳离子类型对混凝土中钢筋腐蚀临界氯离子浓度的影响[J].江苏大学学报(自然科学版),2013,34(4):476-480.
[17]ZHU Q,JIANG L H,CHEN Y,et al.Effect of chloride salt type on chloride binding behavior of concrete[J].Construction and Building Materials,2012(37):512-517.
[18]水工混凝土试验规程:SL 352-2006[S].
[19]PAGE C L.Mechanism of corrosion protection in reinforced concrete marine structures[J].Nature,1975(258):514-515.
[20]金雁南,周双喜.混凝土硫酸盐侵蚀的类型及作用机理[J].华东交通大学学报,2006,23(5):4-8.
[21]ANSSON C M,FRLUNDT,MARKUSSEN J B.The effect of chloride cation type on the corposion of steel in concrete by chloride salts[J].Cement and Concrete Research,1985,15(1):65-73.
[22]XU Y.The influence of sulphates on chloride binding and pore solution chemistry[J].Cement and Concrete Research,1997,27(12):1841-1850.
[23]Michel M,GEORGIN J,AMBROISE J.Improving the mechanical performance of high-grade slag cement by the addition of Portland cement and sulfoaluminate cement[J].Construction and Building Materials,2012(37):291-300.
[24]SURYAVANSHI A K,NARAYAN SWAMY R.Stability of Friedel′s salt in carbonated concrete structural elements[J].Cement and Concrete Research,1996,26(5):729-741.
[25]HOSSAIN K M A,LACHEMI M.Performance of volcanic ash and pumice based blended cement concrete in mixed sulfate environment[J].Cement and Concrete Research,2006,36(6):1123-1133.
[26]ZHANG M,CHEN J,LV Y,et al.Study on the expansion of concrete under attack of sulfate and sulfate chloride ions[J].Construction and Building Materials,2013(39):26-32.
[27]LUO R,CAI Y,WANG C,et al.Study of chloride binding and diffusion in GGBS concrete[J].Cement and Concrete Research,2003,33(1):1-7.
[28]GUERRERO A,GOI S,ALLEGRO V R.Effect of temperature on the durability of class C fly ash belite cement in simulated radio active liquid waste:synergy of chloride and sul-phate ions[J].Hazard.Mater,2009,165(1-3):903-908.