A STUDY ON CHLORIDE ION DIFFUSIVITY OF POROUS AGGREGATE CONCRETES AND IMPROVEMENT METHOD
A STUDY ON CHLORIDE ION DIFFUSIVITY OF POROUS AGGREGATE CONCRETES AND IMPROVEMENT METHOD
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DOI：
10.2208/jsceje.65.30
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
P. Wattanachai;N. Otsuki;Tsuyoshi Saito;T. Nishida
中科院分区：
文献类型：
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作者：
P. Wattanachai;N. Otsuki;Tsuyoshi Saito;T. Nishida
本研究通过考察多孔骨料对混凝土氯离子（Cl-）扩散率和界面过渡区（ITZ）性能的影响，以及养护条件的影响，研究多孔骨料混凝土抗氯离子侵蚀的耐久性；分别是养护温度和养护周期；用四种骨料研究混凝土的Cl-扩散系数和ITZ性能。三种类型的多孔集料；日本人造轻骨料、珊瑚骨料和破碎粘土砖骨料；与破碎的石灰石骨料进行比较。本研究采用了三种不同的水灰比（W/C）。测定了粗集料周围的ITZ的厚度和Cl-扩散系数等特性，并用其来解释多孔集料和养护条件对混凝土Cl-扩散系数的影响。结果表明，日本人工轻骨料混凝土的Cl-扩散系数比普通骨料混凝土低，这是由于日本人工轻骨料具有致密的外壳，Cl-不能穿透骨料和ITZ相。珊瑚和砖类骨料是质量较差的骨料，当其表面处于饱和干燥状态时，其含水量非常高，导致骨料周围的水膜较厚，Cl-很容易穿透。因此，珊瑚和砖骨料制成的混凝土具有较高的Cl-扩散系数，在海洋环境下表现出预期的较差性能。最后，本文成功地提出了用干骨料拌和混凝土来改善劣质骨料的方法。
The purpose of this research is to study the durability of porous aggregate concrete against chloride attack by examining the influence of porous aggregates on chloride ion (Cl-) diffusivity of concrete and Interfacial Transition Zone (ITZ) properties, and to investigate the influence of curing conditions; which are curing temperature and curing period; on Cl- diffusivity and ITZ properties of concrete using four types of aggregate. Three types of porous aggregates; Japanese artificial lightweight aggregate, coral aggregate and crushed clay brick aggregate; are employed to compare with crushed limestone aggregate. Three different water-cement (W/C) ratios are used in this study. The properties of ITZ around coarse aggregates, such as the thickness and the Cl- diffusivity of ITZ, are measured and used to explain the influence of porous aggregates and curing conditions on the Cl- diffusivity of concrete. The results show that Japanese artificial lightweight aggregate concrete has lower Cl- diffusivity compared with normal aggregate concrete because the Japanese artificial lightweight aggregate has a dense outer crust, thus Cl- can not penetrate through aggregate and ITZ phase. Coral and brick aggregates, which are poor quality aggregates, have very high water content when they are in saturated surface-dry condition causing a thicker water film around aggregates and Cl- can easily penetrate through them. Therefore, concrete made from coral and brick aggregates have higher Cl- diffusivity and show expectedly poor performance under marine environment. Finally, the improvement for the poor quality aggregates by using dry aggregates for mixing concrete is successfully proposed in this study.