硫酸钠半浸泡水泥基材料毛细上升与抗氯离子渗透性
DOI:
作者:
作者单位:

宁夏大学土木与水利工程学院

作者简介:

通讯作者:

中图分类号:

TU528

基金项目:

西北典型气候环境与盐蚀条件下RC桥柱墩服役行为及其机理研究


Relationship between Capillary Suction and Chloride Penetration Resistance in Cementitious Materials under Half-submerged Sodium Sulfate Solution
Author:
Affiliation:

School of Civil and Hydraulic Engineering, Ningxia University

Fund Project:

Behavior and mechanism of RC bridge pier under the coupling conditions with typical weather and salt corrosion environment in the northwest of China

  • 摘要
  • |
  • 图/表
  • |
  • 访问统计
  • |
  • 参考文献
  • |
  • 相似文献
  • |
  • 引证文献
  • |
  • 资源附件
  • |
  • 文章评论
    摘要:

    处在硫酸盐和氯盐的复杂盐蚀环境下,服役结构会受到两者产生的耦合作用。文章研究了毛细作用下硫酸钠半浸泡混凝土试样的抗氯离子渗透性能,设计了不同水灰比、不同硫酸钠溶液浓度的砂浆毛细上升试验,测试了硫酸钠半浸泡混凝土试样的SEM、XRD和氯离子电通量,结果表明:硫酸钠半浸泡混凝土抗氯离子渗透性能劣化,前期劣化严重,随着半浸泡时间的延长,抗氯离子渗透性能有所回升,但依然比未浸泡试样的差。结合微观测试结果可知,混凝土抗氯离子渗透性能劣化的主要原因是:前期在毛细作用下硫酸钠溶液填充了混凝土孔隙,减弱了固化氯离子的结合能力,释放了较多的自由氯离子,从而增大了氯离子的扩散量。后期随着浸泡时间的延长和环境湿度的变化,孔隙中的硫酸钠溶液过饱和后形成无水Na<sub>2</sub>SO4和Na<sub>2</sub>SO4.10H<sub>2</sub>O结晶体的混合物,结晶混合物沉淀于孔壁,部分地阻碍了氯离子的扩散,从而减缓了抗氯离子渗透性能的劣化。硫酸钠溶液浓度超过5%以后,随着硫酸钠溶液浓度的升高,毛细上升速度减缓,混凝土抗氯离子渗透性能相应提高。硫酸钠溶液半浸泡下水泥基材料毛细上升快慢可作为衡量混凝土的抗氯离子渗透性能好坏的指标。硫酸钠和氯化钠的复合溶液对硫酸钠毛细上升有延缓作用,因此会改善混凝土的抗氯离子渗透性能。

    Abstract:

    Structure in service may be confronted with the coupling effect under complicated environment like sulfate and chloride corrosions. In this paper, the chloride penetration resistance (CPR) of the concrete half-submerged in sodium sulfate solution (SSS) under capillary suction is studied. The variables with water-cement ratio and the concentration of SSS are designed to test the capillary velocity of the mortar. Methods of SEM, XRD and electric flux of chloride ion are applied to the concrete half-submerged in SSS. The results showed that the CPRs of concrete samples half-submerged in SSS had obvious degradations in early stage, but recovered a bit in the late stage. Combined with the results from microscopic tests, the degradations were attributed to the SSSs filled in the pores of concrete samples. The SSS weaken the ability of chloride ion bounded and released more free chloride ion, as a result increased the electric flux of chloride ion. With the elongation of half-submerged time and the change of the relative humidity of environment, supersaturated SSS came into being Na<sub>2</sub>SO4 and Na<sub>2</sub>SO4.10H<sub>2</sub>O crystals. The admixtures of crystals deposited on the wall of pores, and partially hindered the diffusions of chloride ions, and increased the CPRs. When the concentration of SSS was over 5 percent, the velocity of capillary suction (VCS) slowed down and the CPR of concrete was accordingly enhanced with the increase of the concentration of SSS. The VCS can be used to predict the CPR of concrete. The mixed solutions with sodium sulfate and sodium chloride could retard the VCS and then improve the CPR for concrete.

    参考文献
    相似文献
    引证文献
引用本文
分享
文章指标
  • 点击次数:
  • 下载次数:
  • HTML阅读次数:
  • 引用次数:
历史
  • 收稿日期:2018-09-22
  • 最后修改日期:2019-01-13
  • 录用日期:2019-02-21
  • 在线发布日期:
  • 出版日期: