Effect of pore structures on gas permeability and chloride diffusivity of concrete
Effect of pore structures on gas permeability and chloride diffusivity of concrete
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DOI：
10.1016/j.conbuildmat.2017.12.111
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发表时间：
2018-02
影响因子：
7.4
通讯作者：
Junzhi Zhang;Fan Bian;Yurong Zhang;Z. Fang;C. Fu;Jie Guo
中科院分区：
文献类型：
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作者：
Junzhi Zhang;Fan Bian;Yurong Zhang;Z. Fang;C. Fu;Jie Guo
制作了10个不同水胶比和外加剂的混凝土试件，分析了试验混凝土的渗透性与微观结构的关系。混凝土的气体渗透系数和有效氯离子扩散系数分别采用CemBureau法和ASTM C1202试验进行了测定。此外，还用压汞孔隙仪(MIP)和核磁共振(NMR)分别测定了混凝土的孔结构。结果表明，水胶比和外加剂对10 nm以下的孔径分布影响不大。此外，除玄武岩纤维外，外加剂均能有效降低混凝土的孔隙率。此外，试验混凝土的气体渗透性(氯离子扩散系数)与孔隙率之间存在明显的相关性。核磁共振可获得比分子印迹法更高比例的1-100 nm范围内的孔洞。当孔径为>；100 nm时，结果正好相反。气体渗透系数与孔径为10-1000 nm的贡献孔隙率之间有很好的相关性，而氯离子的扩散系数与孔径为100-1000 nm的贡献孔隙率有很好的相关性。外加剂的加入会改变混凝土的两个整体渗透系数与混凝土微观结构参数之间的关系。
10 concrete specimens with different water-binder ratios and admixtures were manufactured to analyze the relationship between permeability and microstructure of the test concrete. The gas permeability coefficient and effective chloride diffusion coefficient of concrete were measured by Cembureau method and ASTM C1202 test respectively. In addition, the pore structure of concrete was determined by mercury intrusion porosimetry (MIP) and nuclear magnetic resonance (NMR) respectively. Results show that water-binder ratio and admixture have negligible effect on the distribution of pore size below 10 nm. Besides, the addition of admixtures can decrease the porosity of concrete effectively, except basalt fiber. Moreover, there is an obvious correlation between gas permeability (chloride diffusivity) and porosity of the test concrete. A higher proportion of pore within range of 1–100 nm can be obtained by NMR than that by MIP. The results are opposite when the pore size is >100 nm. There is a good correlation between gas permeability coefficients and contributive porosity with pore diameter of 10–1000 nm, meanwhile, chloride diffusivity is well dependent on contributive porosity with pore diameter of 100–1000 nm. The addition of admixtures will change the relationships between two global permeability coefficients and microstructure parameters of concrete.