盐碱-冻融环境下桥梁用混凝土耐久性分析
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摘要
我国"三北地区"桥墩基础长期处于盐碱冻融环境,严重影响了桥墩基础混凝土的耐久性。以1%、2%、4%和6%的Na_2SO_4、NaCl和Na_2SO_4+NaCl作为腐蚀溶液,进行了最大冻融循环120次的不同配比粉煤灰混凝土长期性能室内试验,分析了腐蚀溶液、腐蚀溶液浓度、冻融循环次数、水灰比和粉煤灰掺量等因素对粉煤灰混凝土质量损失率和动弹性模量变化率的影响规律。研究结果表明:(1)相同条件下,溶液对粉煤灰混凝土的质量损失率和动弹模变化率的腐蚀作用:Na_2SO_4+NaCl>NaCl>Na_2SO_4;(2)粉煤灰混凝土的质量会在硫酸钠溶液中出现冻融前期增加而后期损失加剧的现象;(3)粉煤灰混凝土盐碱冻融循环过程中的质量损失和弹性模量减小随水胶比的增大而增大;(4)粉煤灰混凝土的质量损失率和动弹模变化率均随粉煤灰掺量呈现出减小的趋势。
Saline land is widely distributed in"Three-North Area"of China.Saline corrosion and freeze-thaw cycles seriously affect the durability of concrete.Based on 1%,2%,4%and 6%Corrosion solution of Na_2SO_4,NaCl and Na_2SO_4+NaCl,the long-term performance indoor tests of fly ash concrete with maximum freeze-thaw cycle 120 times were conducted.The influence laws of different corrosion solutions,concentration of corrosion solution,freeze-thaw cycle times,W/C and fly ash content on the mass loss rate and dynamic elastic modulus change rate of fly ash concrete were analyzed.The results show that:(1)under the same conditions,the effect order of the solution on the mass loss rate and the dynamic modulus change rate of fly ash concrete:Na_2SO_4+NaCl>NaCl>Na_2SO_4;(2)the quality of fly ash concrete increases in the early freezing-thawing period and decreases in the late freezing-thawing period;(3)the mass loss and elastic modulus decrease of fly ash concrete with the increase of W/B in the process of saline-alkali freeze-thaw cycle;(4)the mass loss rate and the dynamic modulus change rate of fly ash concrete show an exponential decreasing trend with the increase of the fly ash content.
Saline land is widely distributed in"Three-North Area"of China.Saline corrosion and freeze-thaw cycles seriously affect the durability of concrete.Based on 1%,2%,4%and 6%Corrosion solution of Na_2SO_4,NaCl and Na_2SO_4+NaCl,the long-term performance indoor tests of fly ash concrete with maximum freeze-thaw cycle 120 times were conducted.The influence laws of different corrosion solutions,concentration of corrosion solution,freeze-thaw cycle times,W/C and fly ash content on the mass loss rate and dynamic elastic modulus change rate of fly ash concrete were analyzed.The results show that:(1)under the same conditions,the effect order of the solution on the mass loss rate and the dynamic modulus change rate of fly ash concrete:Na_2SO_4+NaCl>NaCl>Na_2SO_4;(2)the quality of fly ash concrete increases in the early freezing-thawing period and decreases in the late freezing-thawing period;(3)the mass loss and elastic modulus decrease of fly ash concrete with the increase of W/B in the process of saline-alkali freeze-thaw cycle;(4)the mass loss rate and the dynamic modulus change rate of fly ash concrete show an exponential decreasing trend with the increase of the fly ash content.
引文
[1]王永州,舒红.论我国城市桥梁发展现状及其发展趋势[J].江西建材,2017(7):184-185.
[2]丁建彤,宁逢伟,王奇.盐碱地下水环境中桩基混凝土耐腐蚀研究[J].混凝土,2015(6):153-156.
[3]郝贠洪,江南,樊金承,等.盐渍土环境下混凝土的抗腐蚀性能研究[J].混凝土,2016(8):8-10.
[4]Hilsdorf H K.Durability of concrete a measurable quantity[J].IABSE Report,1989,57(1):111-123.
[5]Dhir R K,Jones M R,Byars E A,et al.Predicting concrete durability from its absorption[J].Concrete Durability,AP145-64,1988:1177-1194.
[6]周建民.考虑时间因素的混凝土结构分析方法[D].上海:同济大学,2006.
[7]Benjamin G,Jussara T.Durability of an Ultrahigh-Performance Concrete[J].Journal of Materials in Civil Engineering,2007,19(10):848-854.
[8]袭杰,刁波,沈孛,等.冻融与初始裂缝对钢筋混凝土黏结强度的影响[J].混凝土,2014,297(7):15-19.
[9]麻海燕,孙伟,张建业,等.大掺量矿物掺合料混凝土在氯盐、硫酸盐及其复合溶液中的抗冻性[J].南京航空航天大学学报,2010,42(6):797-801.
[10]耿娇,刁波,陈圣刚.冻融与侵蚀作用下引气混凝土劣化微观机理[J].北京航空航天大学学报,2013,39(10):1392-1396.
[11]Dunstan E.R.J.Performance of lignite and subbituminous fly ash in concrete-Aprogress report[R].US bureau of reclama tion REC-ERC-76-1,1976:15.
[12]Wakeley.Geophysical stability of cement based composites in magnesium brines[J].International Cement Microscopy Associa tion,1992(9):333-350.
[13]中国建筑科学研究院.GB/T 50082-2009普通混凝土长期性能和耐久性能试验方法标准[S].北京:中国建筑工业出版社,2010.
[2]丁建彤,宁逢伟,王奇.盐碱地下水环境中桩基混凝土耐腐蚀研究[J].混凝土,2015(6):153-156.
[3]郝贠洪,江南,樊金承,等.盐渍土环境下混凝土的抗腐蚀性能研究[J].混凝土,2016(8):8-10.
[4]Hilsdorf H K.Durability of concrete a measurable quantity[J].IABSE Report,1989,57(1):111-123.
[5]Dhir R K,Jones M R,Byars E A,et al.Predicting concrete durability from its absorption[J].Concrete Durability,AP145-64,1988:1177-1194.
[6]周建民.考虑时间因素的混凝土结构分析方法[D].上海:同济大学,2006.
[7]Benjamin G,Jussara T.Durability of an Ultrahigh-Performance Concrete[J].Journal of Materials in Civil Engineering,2007,19(10):848-854.
[8]袭杰,刁波,沈孛,等.冻融与初始裂缝对钢筋混凝土黏结强度的影响[J].混凝土,2014,297(7):15-19.
[9]麻海燕,孙伟,张建业,等.大掺量矿物掺合料混凝土在氯盐、硫酸盐及其复合溶液中的抗冻性[J].南京航空航天大学学报,2010,42(6):797-801.
[10]耿娇,刁波,陈圣刚.冻融与侵蚀作用下引气混凝土劣化微观机理[J].北京航空航天大学学报,2013,39(10):1392-1396.
[11]Dunstan E.R.J.Performance of lignite and subbituminous fly ash in concrete-Aprogress report[R].US bureau of reclama tion REC-ERC-76-1,1976:15.
[12]Wakeley.Geophysical stability of cement based composites in magnesium brines[J].International Cement Microscopy Associa tion,1992(9):333-350.
[13]中国建筑科学研究院.GB/T 50082-2009普通混凝土长期性能和耐久性能试验方法标准[S].北京:中国建筑工业出版社,2010.