氯离子对混凝土力学及声学性能的影响
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摘要
研究了受NaCl溶液腐蚀后混凝土的力学及声学性能,并采用扫描电子显微镜(SEM)分析弱化机理。结果表明:腐蚀期间混凝土的静态力学性能及纵波波速变化规律相类似,均有明显的降低,且随腐蚀时间增长呈先增大后减小的趋势;混凝土受静压力荷载作用时,自由水通过孔隙水压力,改变了试件内部的应力分布,促进了内部缺陷的扩展;Cl-与水泥水化产物发生化学反应,产物体积大,强度低,破坏了原有结构。Cl-对混凝土具有显著的腐蚀弱化作用,极大地削弱了混凝土静态力学和声学性能。
In order to find the weakening mechanism of Cl-on concrete performance,mechanical and acoustic properties of the concrete corroded by sodium chloride solution were investigated.The results point out that the static mechanical properties and longitudinal wave velocity of the concrete vary similarly,and both of them decreased significantly compared to the contrast group.Furthermore,with the increase of corrosion time,the static mechanical properties and longitudinal wave velocity were first increased and then drop down as the concrete is subjected to static pressure loading,the pore water pressure by free water changes the stress distribution inside the concret,thus the expansion of the internal defect have been accelerated and promoted;Besides,the chemical reaction between Cl-and hydration products of cement produces some by products with large volume and low strength,resulting in the destruction of the original structure.Therefore,the static mechanical properties and acoustic properties of concrete can be geatly weakened by the corrosion of Cl-.
In order to find the weakening mechanism of Cl-on concrete performance,mechanical and acoustic properties of the concrete corroded by sodium chloride solution were investigated.The results point out that the static mechanical properties and longitudinal wave velocity of the concrete vary similarly,and both of them decreased significantly compared to the contrast group.Furthermore,with the increase of corrosion time,the static mechanical properties and longitudinal wave velocity were first increased and then drop down as the concrete is subjected to static pressure loading,the pore water pressure by free water changes the stress distribution inside the concret,thus the expansion of the internal defect have been accelerated and promoted;Besides,the chemical reaction between Cl-and hydration products of cement produces some by products with large volume and low strength,resulting in the destruction of the original structure.Therefore,the static mechanical properties and acoustic properties of concrete can be geatly weakened by the corrosion of Cl-.
引文
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[3]Puatatsananon W,Saouma V E.Nonlinear coupling of carbonation and chloride diffusion in concrete[J].Journal of Materials in Civil Engineering,2005,17(3):264~275.
[4]Ababneh A,Benboudjema F,Xi Y.Chloride penetration in nonsaturated concrete[J].Journal of Materials in Civil Engineering,2003,15(2):183~191.
[5]Yu Z,Chen Y,Liu P,et al.Accelerated simulation of chloride ingress into concrete under drying-wetting alternation condition chloride environment[J].Construction and Building Materials,2015,93:205~213.
[6]Safehian M,Ramezanianpour A A.Assessment of service life models of determination of chloride penetration into silica fume concrete in the severe marine environmental condition[J],Construction and Building Materials,2013,48:287~294.
[7]王元战,周海锋.盐雾环境下受荷混凝土中氯离子扩散试验[J].材料科学与工程学报,2013,31(5):645~650.
[8]郭伟,泰鸿根,孙伟,等.外加剂与水胶比对混凝土氯离子渗透性的影响[J].硅酸盐通报,2010,29(6):1478~1483.
[9]胡瑾,周培渝,董树国,等.提高中等强度等级混凝土抗氯离子渗透性能的研究[J].硅酸盐通报,2014,33(4):913~917.
[10]邹毅.数字式超声波探伤系统的研发[D].长沙:国防科学技术大学,2007.
[11]张俊哲.无损检测技术及其应用(第二版)[M].北京:科学出版社,2010.
[12]王海龙,李庆斌.饱和混凝土静动力抗压强度变化的细观力学机理[J].水利学报,2006,37(8):958~968.
[13]聂良学,许金余,刘远飞,等.硫酸盐环境下混凝土强度变化规律及微观结构分析[J].振动与冲击,2016,20(12):203~208.
[14]胡跃东.氯离子环境下混凝土耐久性研究[D].大连:大连海事大学,2008.
[15]K Kupwade-Patil,EN Allouche.Examination of chlorideinduced corrosion in reinforced geopolymer concretes[J].Journal of Materials in Civil Engineering,2013,25(10):1465~1476.
[16]赵明阶,吴德伦.单轴加载条件下岩石声学参数与应力的关系研究[J].岩石力学与工程学报,1999,18(1):50~54.
[17]赵明阶,徐蓉.用弹性波速计算正交各向异性岩体的裂隙张量[J].重庆建筑大学学报,1999,21(2):42~48.