盐湖卤水侵蚀喷射混凝土衬砌耐久性能退化规律研究
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摘要
我国西部地区盐湖分布广泛,土壤及地下水中含有高浓度硫酸盐、镁盐及氯盐,与衬砌喷射混凝土发生一系列物理化学反应,造成喷射混凝土单层永久衬砌结构耐久性能下降。为系统研究盐湖卤水侵蚀喷射混凝土耐久性能退化规律,以5%Na_2SO_4+5%MgSO_4+3. 5%Na Cl混合溶液为侵蚀介质,采用干湿交替法,分别模拟盐湖卤水及隧道衬砌侵蚀方式,开展喷射混凝土耐久性试验。通过测试混凝土相对动弹性模量、质量变化率、相对抗压强度、损伤层厚度及混凝土中离子含量,研究卤水侵蚀喷射混凝土耐久性能退化规律。结果表明,高水胶比、未掺粉煤灰及高粉煤灰掺量喷射混凝土和模筑混凝土物理力学性能退化速度快,损伤层厚度快速增大,钢纤维可显著提升喷射混凝土抗侵蚀性能。随着侵蚀的进行,混凝土中水溶性钙离子及混凝土p H值下降,水溶性钠离子和氯离子含量增大,酸溶性硫酸根离子含量快速增大。混凝土表面水化产物含量降低,密实度下降,损伤层厚度增大,物理力学性能退化。
Salt lake was widely distributed in Western China. The high concentrations of chlorine salt,sulfate,and magnesium salt in the soil and underground water were the major reasons leading to the deteriorated performance of lining shotcrete and corrosion of reinforcement. In order to research the durability performance deteriorated rules and mechanism of shotcrete lining in brine corrosion environment,by using dry-wet( D&W) alternation method for simulating the corrosion mode of tunnel lining,the shotcrete durability experiment was carried out by 5% Na2 SO4+ 5% MgSO4+ 3. 5% NaCl solution. The durability performance deterioration rules of brine-exposed shotcrete was researched by measuring relative dynamic elastic modulus,mass changing ratio,relative compressive strength,damage depth and ions content. Results show that there has high speed on physical/mechanical properties deterioration and increasing of damage depth of normal concrete and shotcrete with high water-binder ratio and no fly ash or high replacement ratio. Steel fiber can obviously improve the shotcrete corrosion resistance. For D&W cycle increased,water solubility calcite content and pH value decreased. However,water solubility sodium and chloride,and acid solubility sulfate increased.
Salt lake was widely distributed in Western China. The high concentrations of chlorine salt,sulfate,and magnesium salt in the soil and underground water were the major reasons leading to the deteriorated performance of lining shotcrete and corrosion of reinforcement. In order to research the durability performance deteriorated rules and mechanism of shotcrete lining in brine corrosion environment,by using dry-wet( D&W) alternation method for simulating the corrosion mode of tunnel lining,the shotcrete durability experiment was carried out by 5% Na2 SO4+ 5% MgSO4+ 3. 5% NaCl solution. The durability performance deterioration rules of brine-exposed shotcrete was researched by measuring relative dynamic elastic modulus,mass changing ratio,relative compressive strength,damage depth and ions content. Results show that there has high speed on physical/mechanical properties deterioration and increasing of damage depth of normal concrete and shotcrete with high water-binder ratio and no fly ash or high replacement ratio. Steel fiber can obviously improve the shotcrete corrosion resistance. For D&W cycle increased,water solubility calcite content and pH value decreased. However,water solubility sodium and chloride,and acid solubility sulfate increased.
引文
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[13]吴凯,施惠生,徐玲琳,等.集料对含矿粉混凝土抗硫酸镁侵蚀性能的影响[J].建筑材料学报,2016,19(3):442-448.
[14] Tan Y,Yu H,Ma H,et al. Study on the micro-crack evolution of concrete subjected to stress corrosion and magnesium sulfate[J]. Construction and Building Materials,2017,141:453-460.
[15] Alnahhal M F,Alengaram U J,Jumaat M Z,et al. Effect of aggressive chemicals on durability and microstructure properties of concrete containing crushed new concrete aggregate and non-traditional supplementary cementitious materials[J]. Construction and Building Materials,2018,163:482-495.
[16]王家滨,牛荻涛,周宇,等.海洋环境喷射混凝土抗氯离子侵蚀性能试验研究[J].工业建筑,2015,45(9):121-125.
[17] Wang J,Niu D,Zhang Y. Investigation of sulfate attack resistance of shotcrete under dry-wet cycles[J]. Journal of Wuhan University of Technology(Materials Science Edition),2016,31(6):1329-1335.
[18] Wang J,Niu D,Zhang Y. Mechanical properties,permeability and durability of accelerated shotcrete[J]. Construction and Building Materials,2015,95:312-328.
[19]胡晓鹏,孙广帅,张成中,等.混凝土早期碳化性能的试验研究[J].西安建筑科技大学学报(自然科学版),2017,49(4):492-496.
[20]高润东,赵顺波,李庆斌,等.干湿循环作用下混凝土硫酸盐侵蚀劣化机理试验研究[J].土木工程学报,2010(2):48-54.
[2] Hemphill G B. Practical tunnel construction[M]. Hoboken:Jone Wiley&Sons,2013:309-322.
[3] Wang J,Niu D,Ding S,et al. Microstructure,permeability and mechanical properties of accelerated shotcrete at different curing age[J].Construction and Building Materials,2015(78):203-216.
[4] Leung C K Y,Lai R,Lee A Y F. Properties of wet-mixed fiber reinforced shotcrete and fiber reinforced concrete with similar composition[J].Cement and Concrete Research,2005(35):788-795.
[5] Franzen T,Garshol K F,Tomisawa N. Sprayed concrete for final lining:ITA working group report[J]. Tunneling and Underground Space Technology,2001(16):295-309.
[6]乔宏霞,朱彬荣,陈丁山.西宁盐渍土地区混凝土劣化机理试验研究[J].应用基础与工程科学学报,2017,25(4):805-815.
[7]余红发,孙伟,王甲春,等.盐湖地区混凝土的长期腐蚀产物与腐蚀机理[J].硅酸盐学报,2003,31(5):434-440.
[8] Valipour M,Pargar F,Shekarchi M,et al. In situ study of chloride ingress in concretes containing natural zeolite,metakaolin and silica fume exposed to various exposure conditions in a harsh marine environment[J]. Construction and Building Materials,2013,46(3):63-70.
[9]金伟良,张奕,卢振勇.非饱和状态下氯离子在混凝土中的渗透机理及计算模型[J].硅酸盐学报,2008,36(10):1362-1369.
[10]刘赞群,候乐,邓德华,等.碳化混凝土硫酸钠盐结晶破坏[J].硅酸盐学报,2017,45(11):1621-1628.
[11] Rahman M M,Bassuoni M T. Thaumasite sulfate attack on concrete:mechanisms,influential factors and mitigation[J]. Construction and Building Materials,2014,73:652-662.
[12]金祖权,孙伟,张云升,等.混凝土在硫酸盐、氯盐溶液中的损伤过程[J].硅酸盐学报,2006,34(5):630-635.
[13]吴凯,施惠生,徐玲琳,等.集料对含矿粉混凝土抗硫酸镁侵蚀性能的影响[J].建筑材料学报,2016,19(3):442-448.
[14] Tan Y,Yu H,Ma H,et al. Study on the micro-crack evolution of concrete subjected to stress corrosion and magnesium sulfate[J]. Construction and Building Materials,2017,141:453-460.
[15] Alnahhal M F,Alengaram U J,Jumaat M Z,et al. Effect of aggressive chemicals on durability and microstructure properties of concrete containing crushed new concrete aggregate and non-traditional supplementary cementitious materials[J]. Construction and Building Materials,2018,163:482-495.
[16]王家滨,牛荻涛,周宇,等.海洋环境喷射混凝土抗氯离子侵蚀性能试验研究[J].工业建筑,2015,45(9):121-125.
[17] Wang J,Niu D,Zhang Y. Investigation of sulfate attack resistance of shotcrete under dry-wet cycles[J]. Journal of Wuhan University of Technology(Materials Science Edition),2016,31(6):1329-1335.
[18] Wang J,Niu D,Zhang Y. Mechanical properties,permeability and durability of accelerated shotcrete[J]. Construction and Building Materials,2015,95:312-328.
[19]胡晓鹏,孙广帅,张成中,等.混凝土早期碳化性能的试验研究[J].西安建筑科技大学学报(自然科学版),2017,49(4):492-496.
[20]高润东,赵顺波,李庆斌,等.干湿循环作用下混凝土硫酸盐侵蚀劣化机理试验研究[J].土木工程学报,2010(2):48-54.