Effect of sulfate solution concentration on the deterioration mechanism and physical properties of concrete
Effect of sulfate solution concentration on the deterioration mechanism and physical properties of concrete
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硫酸盐溶液浓度对混凝土劣化机理及物理性能的影响
DOI：
10.1016/j.conbuildmat.2019.08.022
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发表时间：
2019-12-10
影响因子：
7.4
通讯作者：
Lu, Zhaohui
中科院分区：
文献类型：
--
作者：
Liu, Peng;Chen, Ying;Lu, Zhaohui
研究了硫酸钠溶液浓度和侵蚀龄期对混凝土轴心抗压强度、硫酸根分布、动弹性模量、电化学性能和荷载-位移曲线的影响。根据化学热力学理论，推导出硫酸钠溶液浓度与硫酸盐产品之间的内在联系。采用不同的测试仪器对硫酸盐侵蚀前后混凝土的孔隙率及孔分布、相组成、奈奎斯特谱、微观结构和形貌进行了分析。结果表明，随着硫酸钠溶液浓度的增加，混凝土的轴心抗压强度和荷载-位移曲线先增大后减小。随着侵蚀龄期的增加，混凝土强度等级越低，硫酸盐侵蚀混凝土轴心抗压强度降低越大。硫酸盐侵蚀的主要产物为棒状钙矾石和片状石膏，对混凝土的性能起着双重作用。混凝土表面硫酸根离子含量随着硫酸盐溶液浓度的增加而增加，并且随着深度的增加也先增加后减少，直到达到一定值。硫酸盐溶液作用下混凝土的横向和纵向动弹性模量随硫酸盐溶液浓度的增加而变化。混凝土横向和纵向动弹性模量波形变化的包络线均可用指数函数表示。孔隙溶液电阻和电荷转移电阻的变化随硫酸盐溶液浓度的增加而增大，说明硫酸盐侵蚀使混凝土试件的微观结构发生了劣化。(C)2019爱思唯尔有限公司版权所有。
Effects of sodium sulfate solution concentration and erosion age on axial compressive strength, sulfate ion distribution, dynamic elastic modulus, electrochemical performance and load-displacement curves of concrete were investigated. Based on the chemical thermodynamics theory, the internal relationship between sodium sulfate solution concentration and sulfate products was deduced. The porosity and pore distribution, phase composition, Nyquist spectrum, micro structure and morphology of concrete before and after sulfate attack were also analyzed by different testing instruments. The results indicate that the axial compressive strength and load-displacement curves of concrete first increase and then decrease with increasing sodium sulfate solution concentration. With increase of erosion age, the lower the strength grade of concrete is, the larger the reduction of axial compressive strength of concrete attacked by sulfate. The main products of sulfate attack are claviform ettringite and lamellar gypsum, which play double effects on performance of the concrete. The sulfate ion content in concrete surface increases with the increasing of sulfate solution concentration, and it also increases first and then decreases until to a certain value with depth. The transverse and longitudinal dynamic elastic moduli of concrete attacked by sulfate solution change with increasing of the sulfate solution concentration. The envelope curves of the waveform change of transverse and longitudinal dynamic elastic moduli of concrete can be represented as exponential function. The change of electric resistance of pore solution and charge-transfer resistance increases with sulfate solution concentration, which indicates the micro structure of concrete specimens are degraded by sulfate attacked. (C) 2019 Elsevier Ltd. All rights reserved.