Permeation Properties and Pore Structure of Surface Layer of Fly Ash Concrete.
Permeation Properties and Pore Structure of Surface Layer of Fly Ash Concrete.
复制标题
粉煤灰混凝土表层渗透性能及孔结构
DOI：
10.3390/ma7064282
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发表时间：
2014-05-30
期刊：
影响因子：
--
通讯作者：
Pan D
中科院分区：
文献类型：
--
作者：
Liu J;Qiu Q;Xing F;Pan D
本文对含粉煤灰混凝土面层的渗透特性和孔隙结构进行了试验研究。研究了含有不同剂量的粉煤灰作为水泥替代品的混凝土（分别占总水泥材料重量的15%和30%）。不掺粉煤灰的混凝土也作为参考试样。通过室内试验确定了混凝土的表层性能，包括氯离子输运、表观透水性和孔隙结构。结果表明：在试验前期，粉煤灰的掺入促进了混凝土表层氯离子的渗入，但粉煤灰替代比例对其影响不大；在氯离子浸渍过程中，掺加和不掺加粉煤灰的混凝土表层氯离子浓度基本相同。此外，混凝土表面透水性与粉煤灰掺量和氯离子暴露时间密切相关。采用压汞孔法（MIP）和扫描电镜（SEM）对孔隙结构进行了表征。蒸馏水对混凝土孔隙结构的改性是由粉煤灰的火山灰反应和钙浸出效应决定的。浸出时间为180 d时，火山灰反应更为明显，浸出时间为270 d时，钙浸出效果更为明显。
This paper presents an experimental study on the nature of permeation properties and pore structure of concrete surface layers containing fly ash. Concretes containing different dosages of fly ash as a replacement for cement (15% and 30% by weight of total cement materials, respectively) were investigated. Concrete without any fly ash added was also employed as the reference specimen. Laboratory tests were conducted to determine the surface layer properties of concrete including chloride transport, apparent water permeability and pore structure. The results demonstrate that incorporation of fly ash, for the early test period, promotes the chloride ingress at the surface layer of concrete but substituting proportions of fly ash may have little impact on it. With the process of chloride immersion, the chloride concentration at the surface layer of concrete with or without fly ash was found to be nearly the same. In addition, it is suggested that the water permeability at the concrete surface area is closely related to the fly ash contents as well as the chloride exposure time. Pore structure was characterized by means of mercury intrusion porosimetry (MIP) test and the scanning electron microscopy (SEM) images. The modification of pore structure of concrete submersed in distilled water is determined by the pozzolanic reaction of fly ash and the calcium leaching effect. The pozzolanic reaction was more dominant at the immersion time of 180 days while the calcium leaching effect became more evident after 270 days.