西安建筑科技大学学报(自然科学版)

为了研究氯盐侵蚀作用对混凝土微观结构的损伤规律,进行不同浓度的氯盐溶液浸泡试验,分别对浸泡28 d、56 d和84 d的混凝土进行质量测试和低场核磁共振扫描(LF-NMR),在此基础上分析了混凝土受氯盐腐蚀的损伤机理.研究结果表明:随着氯盐浓度的增加,混凝土试件的质量损失率呈线性增加规律,且质量损失率随浸泡时间增加也有明显的上升趋势; 浸泡28天的混凝土T2分布曲线呈“双峰型”分布,而浸泡56和84天的混凝土T2分布曲线呈“三峰型”分布; 质量损失率与谱面积具有良好的线性关系,说明根据T2谱面积可以对混凝土的微观结构损伤进行合理描述; 结合扫描电子显微镜(SEM)图像分析,认为氯盐浸泡过程中产生的渗透压力和化学腐蚀是影响混凝土孔隙结构的主要原因.研究结果为混凝土耐久性在氯盐侵蚀条件下的劣化规律认识提供了一定参考.

In order to study the chlorine salt erosion damage law of marine engineering concrete, different concentrations of chloride salt solution immersion tests with a soaking time of 28, 56 and 84 days were conducted to concrete.Low field NMR scans(LF-NMR)were conducted to analyze the damage mechanism of concrete corrosion by chlorine salt.Results showed that the mass loss rate of concrete specimens increased linearly with the increase of chloride concentration, and the mass loss rate also increased with the increase of soaking time.The T2 distribution curves of concrete soaked for 28 days were bimodal, while the T2 distribution curves of concrete soaked for 56 and 84 days were trimodal.The mass loss rate has a good linear relationship with the spectral area, which indicates that the microstructure damage of concrete can be described reasonably according to T2 spectral area.Combined with SEM image analysis, it is concluded that the seepage pressure and chemical corrosion caused by chlorine salt immersion are the main reasons that affect the pore structure of marine concrete.The results provide a reference for the understanding of the deterioration law of concrete durability under the condition of chloride erosion.

引言
1 试验材料和方法
2 试验结果分析
3 结论

表1 海工混凝土的配合比<br/>Tab.1 The mix proportion of marine concrete

表1 海工混凝土的配合比
Tab.1 The mix proportion of marine concrete

图1 低场核磁共振成像扫描仪<br/>Fig.1 The low field NMR scanner

图1 低场核磁共振成像扫描仪
Fig.1 The low field NMR scanner

图2 浸泡84 d的混凝土试样外观<br/>Fig.2 Appearance of concrete samples soaked for 84 days

图2 浸泡84 d的混凝土试样外观
Fig.2 Appearance of concrete samples soaked for 84 days

图3 质量损失率与氯离子浓度的关系<br/>Fig.3 Relationship between mass loss rate and chloride ion concentration

图3 质量损失率与氯离子浓度的关系
Fig.3 Relationship between mass loss rate and chloride ion concentration

表2 混凝土试样的T2谱面积<br/>Tab.2 T2 spectral area of concrete sample

表2 混凝土试样的T2谱面积
Tab.2 T2 spectral area of concrete sample

图4 氯盐干湿循环下混凝土的T2分布谱<br/>Fig.4 T2 curves of concrete under various cycles

图4 氯盐干湿循环下混凝土的T2分布谱
Fig.4 T2 curves of concrete under various cycles

图5 质量损失率与T2谱面积的关系<br/>Fig.5 Corelation curves of spectrum area and cycles

图5 质量损失率与T2谱面积的关系
Fig.5 Corelation curves of spectrum area and cycles

图6 氯盐侵蚀前后中混凝土的微观SEM图<br/>Fig.6 SEM images of concrete before and after chlorine salt erosion

图6 氯盐侵蚀前后中混凝土的微观SEM图
Fig.6 SEM images of concrete before and after chlorine salt erosion

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备注

引言

1 试验材料和方法

2 试验结果分析

3 结论

期刊信息